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Screening for Colon Cancer in Older Adults: Risks, Benefits, and When to Stop

      Abstract

      Colorectal cancer (CRC) is the fourth leading cause of cancer and second leading cause of mortality from cancer in the United States. As the population ages, decisions regarding the initiation and cessation of screening and surveillance for CRC are of increasing importance. In elderly patients, the risks of CRC and the presenting signs and symptoms are similar to those in younger patients. Screening and ongoing surveillance should be considered in patients who have a life expectancy of 10 years or more. Life expectancy estimates can be calculated using online calculators. If screening is deemed appropriate, the choice of which test to use first is unclear. Currently, there are a number of modalities available to screen for CRC, including both invasive modalities (eg, colonoscopy, sigmoidoscopy, capsule colonoscopy, and computed tomographic colonography) and noninvasive modalities (fecal immunochemical test, stool DNA testing, and blood testing). Colonoscopy and other invasive testing options are considered safe, but the risks of complications of the bowel preparation, the procedure, and sedation medications are all increased in older patients. In contrast, noninvasive testing provides a safe initial test; however, it is important to consider the increased false-positive rates in the elderly, and a positive test result will usually necessitate colonoscopy to establish the diagnosis. Ongoing screening and surveillance should be a shared decision-making process with the patient based on multiple factors including the patient’s morbidity and mortality risk from CRC and his or her underlying comorbidities, the patient’s functional status, and the patient’s preferences for screening. Ultimately, the decision to initiate or discontinue screening for CRC in older patients should be done based on a case-by-case individualized discussion.

      Abbreviations and Acronyms:

      ACS (American Cancer Society), ASGE (American Society of Gastrointestinal Endoscopy), CRC (colorectal cancer), CT (computed tomographic), FIT (fecal immunochemical test), FOBT (fecal occult blood test), NNS (number needed to screen), US-MSTF (US Multi-Society Task Force)
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      Learning Objectives: On completion of this article, you should be able to (1) recognize the risk of colorectal cancer in the elderly, (2) determine when to stop screening for colorectal cancer in the elderly, and (3) explain the difference in the risks and benefits of the available colorectal cancer screening modalities.
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      Colorectal cancer (CRC) is the fourth leading cause of cancer and second leading cause of mortality from cancer in the United States. Forty-two percent of new diagnoses of CRC are in patients 65 years and older. The risk is even higher in women, with 27% of cases diagnosed at the age of 80 years and above, with 40% of deaths occurring in this age group.
      • Siegel R.L.
      • Miller K.D.
      • Fedewa S.A.
      • et al.
      Colorectal cancer statistics, 2017.
      Although age is not a modifiable risk factor for developing CRC, the benefits of screening for CRC in older adults is less clear. In general, colon cancer screening is used as a means to identify adenomatous polyps and remove them before the development of cancer and has thus far been considered the criterion standard in CRC screening. Currently, there are multiple modalities to screen for CRC, including noninvasive modalities (stool-based testing, radiologic testing, and blood testing) and invasive modalities (endoscopic screening including colonoscopy or sigmoidoscopy). However, all these procedures are not without risk. Recent guidelines from the US Preventive Services Task Force recommend against screening individuals older than 85 years for CRC and noted uncertainty in the benefits of screening patients between the ages of 76 and 85 years.
      U.S. Preventive Services Task Force
      Screening for colorectal cancer: U.S. Preventive Services Task Force recommendation statement.
      However, the overall benefit of screening and surveillance is actually rooted in the patient’s life expectancy combined with the risk of morbidity and mortality from developing a malignant neoplasm. As a result, though new screening for CRC may not be appropriate at the population level, select individuals may still benefit from screening regardless of their age. This review summarizes the current literature on screening for CRC in older adults. Older adults are defined as those 65 years and older.

      Epidemiology

      Colorectal cancer incidence and mortality have decreased dramatically in the past decade, secondary to increased CRC screening and surveillance. In 2017, it was projected that 135,430 individuals would be newly diagnosed with CRC and 40,260 deaths would occur from the disease. However, trends in CRC incidence vary by age, with 90% of new CRC diagnoses in those older than 50 years
      • Siegel R.L.
      • Miller K.D.
      • Fedewa S.A.
      • et al.
      Colorectal cancer statistics, 2017.
      (Figures 1 and 2).
      Figure thumbnail gr1
      Figure 1The Surveillance, Epidemiology and End Results Program data on age-specific colon cancer incidence rates from 2011 to 2015.
      Figure thumbnail gr2
      Figure 2The Surveillance, Epidemiology and End Results Program data on age-specific rectal cancer incidence rates from 2011 to 2015.
      In older adults, CRC incidence rates have dropped precipitously from 298.3 per 100,000 to 186.8 per 100,000 from 2000 to 2013. This reduction in both incidence of and mortality from CRC is most likely due to nationwide screening and surveillance programs for CRC. Despite this decline, in 2017, 42% of new cases of CRC occurred in people 65 years and older. Compared with individuals aged between 50 and 64 years with an average decrease in incidence of CRC by 1.4% per year, older adult individuals have reported an average decrease in the incidence of CRC by 4% per year. Unlike in those individuals younger than 50 years, this has been shown irrespective of tumor location, stage, or race/ethnicity in older adults.
      • Siegel R.L.
      • Miller K.D.
      • Fedewa S.A.
      • et al.
      Colorectal cancer statistics, 2017.

      Signs and Symptoms

      Colorectal cancer can present with varying symptoms depending on the site of cancer in the colon or rectum. Symptoms are most often changes in stool caliber, followed by gastrointestinal bleeding, abdominal pain, and constipation in patients aged 65 to 79 years. Symptoms are slightly different in those 80 years and older. Weight loss is more common in this age group, and presenting symptoms are predominantly changes in stool caliber followed by abdominal pain and gastrointestinal bleeding. Infrequently, patients present with abdominal obstruction.
      • Mouchli M.A.
      • Ouk L.
      • Scheitel M.R.
      • et al.
      Colonoscopy surveillance for high risk polyps does not always prevent colorectal cancer.
      • Kahi C.J.
      • Myers L.J.
      • Slaven J.E.
      • et al.
      Lower endoscopy reduces colorectal cancer incidence in older individuals.
      • Esteva M.
      • Ruiz A.
      • Ramos M.
      • et al.
      DECCIRE GROUP
      Age differences in presentation, diagnosis pathway and management of colorectal cancer.

      Risk of New Adenoma

      Precancerous polyps, including adenomatous and advanced polyps (polyps >10 mm, villous/tubulovillous features, and high grade dysplasia), have an increased prevalence in the older population.
      • Neugut A.I.
      • Jacobson J.S.
      • De Vivo I.
      Epidemiology of colorectal adenomatous polyps.
      • Lieberman D.A.
      • Williams J.L.
      • Holub J.L.
      • et al.
      Race, ethnicity, and sex affect risk for polyps >9 mm in average-risk individuals.
      • Omata F.
      • Brown W.R.
      • Tokuda Y.
      • et al.
      Modifiable risk factors for colorectal neoplasms and hyperplastic polyps.
      • Strul H.
      • Kariv R.
      • Leshno M.
      • et al.
      The prevalence rate and anatomic location of colorectal adenoma and cancer detected by colonoscopy in average-risk individuals aged 40-80 years.
      In a large Veterans Affairs Hospital cohort of 17,732 asymptomatic men undergoing colonoscopy screening, the prevalence of advanced neoplasia increased from 5.7% in the youngest patients (50-59 years old) to 13% in the oldest patients (70-75 years old). Furthermore, advanced proximal neoplasia increased with age (P<.001): the prevalence was 2% for patients who were 50 to 59 years old, 4.9% for those who were 60 to 69 years old, and 5.9% for those who were 70 to 75 years old.
      • Lieberman D.A.
      • Weiss D.G.
      • Bond J.H.
      • Ahnen D.J.
      • Garewal H.
      • Chejfec G.
      Use of colonoscopy to screen asymptomatic adults for colorectal cancer. Veterans Affairs Cooperative Study Group 380.
      In another study of average risk in men and women undergoing colonoscopy screening, the prevalence and severity of neoplastic changes from adenoma through advanced adenoma to invasive carcinoma were markedly related to aging, with an odds ratio of 1.78 per increase of 10 years of age. In particular, healthy older individuals aged 76 to 80 years at average risk of CRC reported rates of advanced neoplasia and CRC (14.3% and 2.6%, respectively) that were twice as high as the rates in the main age group of 50 to 75 years.
      • Strul H.
      • Kariv R.
      • Leshno M.
      • et al.
      The prevalence rate and anatomic location of colorectal adenoma and cancer detected by colonoscopy in average-risk individuals aged 40-80 years.
      Age has been associated with several other polyp factors. In addition to adenomatous polyps, sessile serrated adenomas have been associated with increasing age,
      • Omata F.
      • Brown W.R.
      • Tokuda Y.
      • et al.
      Modifiable risk factors for colorectal neoplasms and hyperplastic polyps.
      as have larger and more right-sided polyps.
      • Glebov O.K.
      • Rodriguez L.M.
      • Nakahara K.
      • et al.
      Distinguishing right from left colon by the pattern of gene expression.
      • Rex D.K.
      • Boland C.R.
      • Dominitz J.A.
      • et al.
      Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer.
      Furthermore, older men tend to have a higher prevalence of adenomatous polyps than do older women.
      • Strul H.
      • Kariv R.
      • Leshno M.
      • et al.
      The prevalence rate and anatomic location of colorectal adenoma and cancer detected by colonoscopy in average-risk individuals aged 40-80 years.
      • Lieberman D.A.
      • Weiss D.G.
      • Bond J.H.
      • Ahnen D.J.
      • Garewal H.
      • Chejfec G.
      Use of colonoscopy to screen asymptomatic adults for colorectal cancer. Veterans Affairs Cooperative Study Group 380.
      Although the risk of adenoma and CRC is significantly affected by age, the recurrence of polyps and advanced polyps have not been associated with increased age.
      • Noshirwani K.C.
      • van Stolk R.U.
      • Rybicki L.A.
      • Beck G.J.
      Adenoma size and number are predictive of adenoma recurrence: implications for surveillance colonoscopy.
      • Harewood G.C.
      • Lawlor G.O.
      • Larson M.V.
      Incident rates of colonic neoplasia in older patients: when should we stop screening?.
      • Harewood G.C.
      • Lawlor G.O.
      Incident rates of colonic neoplasia according to age and gender: implications for surveillance colonoscopy intervals.
      Only 1 study reported that older age (≥60 years) was a factor associated with recurrent polyps and advanced lesions, but this was not a substantial independent variable in a multivariate analysis.
      • Winawer S.J.
      • Zauber A.G.
      • O’Brien M.J.
      • et al.
      The National Polyp Study Workgroup. Randomized comparison of surveillance intervals after colonoscopic removal of newly diagnosed adenomatous polyps.
      Factors on index colonoscopy such as large polyps (polyp ≥1 cm),
      • Harewood G.C.
      • Lawlor G.O.
      Incident rates of colonic neoplasia according to age and gender: implications for surveillance colonoscopy intervals.
      number of polyps,
      • van Heijningen E.M.
      • Lansdorp-Vogelaar I.
      • Kuipers E.J.
      • et al.
      Features of adenoma and colonoscopy associated with recurrent colorectal neoplasia based on a large community-based study.
      insufficient bowel preparation/incomplete examination, and incomplete resection of polyps
      • Pohl H.
      • Srivastava A.
      • Bensen S.P.
      • et al.
      Incomplete polyp resection during colonoscopy—results of the complete adenoma resection (CARE) study.
      were more associated with recurrence. Two meta-analyses reported that the number of polyps, size of polyps, and polyp histology were most strongly associated with advanced adenoma on surveillance colonoscopy.
      • Martinez M.E.
      • Baron J.A.
      • Lieberman D.A.
      • et al.
      A pooled analysis of advanced colorectal neoplasia diagnoses after colonoscopic polypectomy.
      • Saini S.D.
      • Kim H.M.
      • Schoenfeld P.
      Incidence of advanced adenomas at surveillance colonoscopy in patients with a personal history of colon adenomas: a meta-analysis and systematic review.
      However, Martinez et al
      • Martinez M.E.
      • Baron J.A.
      • Lieberman D.A.
      • et al.
      A pooled analysis of advanced colorectal neoplasia diagnoses after colonoscopic polypectomy.
      did report that in multivariate analyses, older age was associated significantly with an increased risk of metachronous advanced neoplasia.

      Decision to Screen or Not to Screen

      The decision to screen older adults for CRC is complex. Although the current US Preventive Services Task Force
      • Kahi C.J.
      • Myers L.J.
      • Slaven J.E.
      • et al.
      Lower endoscopy reduces colorectal cancer incidence in older individuals.
      guideline recommends against screening in patients older than 85 years,
      U.S. Preventive Services Task Force
      Screening for colorectal cancer: U.S. Preventive Services Task Force recommendation statement.
      there are no data that the benefits of screening cease at any particular age alone as the only factor in consideration. Although, at a population level, the overall benefit of screening may be less clear, one must assess the risks and benefits of screening older adults at an individual level and not simply based on age. Older adults are at an increased risk of CRC in general and of developing more advanced CRC.
      • Siegel R.L.
      • Miller K.D.
      • Fedewa S.A.
      • et al.
      Colorectal cancer statistics, 2017.
      However, detecting disease early in its course is associated with better surgical outcomes (eg, eradicating stage 1 CRC) and tolerance of the operations themselves in this population.
      • O’Connell J.B.
      • Maggard M.A.
      • Ko C.Y.
      Colon cancer survival rates with the new American Joint Committee on Cancer sixth edition staging.
      • Kordatou Z.
      • Kountourakis P.
      • Papamichael D.
      Treatment of older patients with colorectal cancer: a perspective review.
      To that end, discontinuing screening may portend a worse outcome in cases in which CRC is detected only at a more advanced stage without curative possibilities.
      To determine who may benefit from screening, one must balance the risk of morbidity and mortality from cancer against the individual mortality risk related to other competing health factors (Figure 3). For the clinician, estimating life expectancy for an individual is challenging. Diseases such as congestive heart failure, end-stage renal disease, advanced chronic obstructive pulmonary disease, advanced dementia, and severe functional limitations in activities of daily living all predict a shorter life expectancy compared with age-matched controls. Previously developed tools, such as the National Center for Health Statistics Life tables of the United States, may aid in predicting the life expectancy of a patient of a particular age and race
      • Arias E.
      • Rostron B.L.
      • Tejada-Vera B.
      United States life tables, 2017.
      ; however, it does not account for compounding health factors nor does it incorporate functional status. ePrognosis (http://cancerscreening.eprognosis.org/screening/) can also be used as a tool to aid in predicting life expectancy and takes into consideration the overall assessment of a patient’s health, age, comorbidities, and cognition.
      • McClymont K.M.
      • Lee S.J.
      • Schonberg M.A.
      • Widera E.
      • Miao Y.
      • Smith A.K.
      Usefulness and effect of online prognostic calculators.
      Cognitive and capacity assessments are necessary to ensure that patients are able to engage in shared decision making appropriately and are recommended by the consensus guidelines from the American Society of Gastrointestinal Endoscopy (ASGE) in older adults.
      • Rex D.K.
      • Boland C.R.
      • Dominitz J.A.
      • et al.
      Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer.
      Figure thumbnail gr3
      Figure 3Algorithm for screening for colorectal cancer in the elderly.
      Once life expectancy is estimated, the clinician can then assess whether a screening test is appropriate. In general, for CRC, the lag time for benefit from screening is approximately 10 years.
      • Inadomi J.M.
      • Sonnenberg A.
      The impact of colorectal cancer screening on life expectancy.
      • Lin O.S.
      • Kozarek R.A.
      • Schembre D.B.
      • et al.
      Screening colonoscopy in very elderly patients: prevalence of neoplasia and estimated impact on life expectancy.
      Putting this in context, if a patient’s life expectancy is estimated to be less than 10 years, screening for CRC would be unlikely to provide a mortality benefit to the patient. In contrast, a “healthy” 85-year-old individual without any significant comorbidities and excellent functional status is likely to have a life expectancy of 10 years or more and may reap benefits of screening for CRC, given the increased prevalence of adenomatous polyps above the age of 75.

      How to Screen for CRC

      Although there are a number of tests available to screen for CRC, most have not been validated in an elderly cohort and extrapolated evidence is used from available data in younger patients. The decision about which test one chooses is based on a discussion with the patient and the risk/benefit of each test and any follow-up testing that may be required after a positive test result (Table 1).
      Table 1Key Features, Risks, and Benefits of Available Screening Modalities in CRC
      Screening testKey featuresRisksBenefits
      ColonoscopyCriterion standard; 50% reduction in CRC incidence in older adultsHighest rate of complications: perforation, gastrointestinal bleed, and cardiovascular risks; requires bowel preparationPolyp removal at the time of screening
      Sigmoidoscopy20% reduction in CRC incidence in older adults; 35% reduction in mortalityRight colon not evaluated; cardiovascular risks associated with sedation if used; requires bowel preparationFewer complications than in colonoscopy; may be able to perform without sedation
      Capsule colonoscopyNot studied in older adultsRequires colonoscopy if lesions visualized; requires bowel preparation; incomplete visualization if poor preparation; risk of aspiration of the capsule and retained capsuleNo sedation required; if no lesions detected and adequate preparation, can provide reassurance without risks of invasive testing
      CT colonographyNot studied in older adults; requires adequate insufflation, which may prove more challenging in older adultsRequires colonoscopy if lesions visualized; requires bowel preparation; radiation exposure; risk of perforation from insufflation; incidental findingsNo sedation required; if no lesions detected and adequate preparation, can provide reassurance without risks of invasive testing
      FOBT11% to 16% reduction in mortality from CRC in older adults; highest false-positive rate of noninvasive testing optionsRequires colonoscopy if positive results; high false-positive rate (US-MSTF recommends against its use as a result)If negative results, may provide reassurance without risks of invasive testing
      FITSensitivity for detecting CRC in older adults higher than that with FOBT but lower than that with multi-target stool DNA testing (73.8%)Requires colonoscopy if positive resultsImproved sensitivity and specificity compared with FOBT; if negative results, may provide reassurance without risks of invasive testing
      Stool DNA testingHighest sensitivity for detecting CRC (92%) compared with FIT; best sensitivityRequires colonoscopy if positive resultsImproved sensitivity and specificity compared with other noninvasive testing; highly sensitive for advanced polpys; if negative results, may provide reassurance without risks of invasive testing
      Septin 9 blood testingSpecificity as high as 92%; limited data in the elderlyRequires colonoscopy if positive results; false-positive risk may increase with ageIf negative results, may provide reassurance without risks of invasive testing
      CRC = colorectal cancer; FIT = fecal immunochemical test; FOBT = fecal occult blood test; US-MSTF = US Multi-Society Task Force; USPSTF = US Preventive Services Task Force.
      Screening tests can be categorized into invasive and noninvasive modalities. Invasive modalities include colonoscopy, sigmoidoscopy, capsule colonoscopy, and computed tomographic (CT) colonography. Noninvasive testing options include stool guaiac fecal occult blood test (FOBT), fecal immunochemical test (FIT), stool DNA testing, and blood testing.

      Invasive Modalities With Direct Visualization of Polyps

      Colonoscopy

      Although colonoscopy has traditionally been considered the criterion standard for colon cancer screening, there are no randomized controlled trials specifically performed in the older population. However, 1 prospective study indicated a 50% reduction in the incidence of CRC in older adult individuals 75 years and older if their last procedure was more than 5 years ago.
      • Nishihara R.
      • Wu K.
      • Lochhead P.
      • et al.
      Long-term colorectal-cancer incidence and mortality after lower endoscopy.
      To prevent 1 CRC, the number needed to screen (NNS) is estimated to be 126 in men and 98 in women aged 75 to 79 years.
      • Ko C.W.
      • Sonnenberg A.
      Comparing risks and benefits of colorectal cancer screening in elderly patients.
      The main benefit of colonoscopy is that it enables both screening and polyp removal in a single procedure. With adequate resection of polyps, the risk of CRC should be mitigated. Although the procedure is cost-effective, the risk of complications is increased in older adults. Possible complications include perforation, gastrointestinal bleeding, and cardiovascular risks associated with anesthetic agents.
      • Fisher D.A.
      • Maple J.T.
      • Ben-Menachem T.
      • et al.
      ASGE Standards of Practice Committee
      Complications of colonoscopy.
      In particular, an increased risk of gastrointestinal perforation may occur in the older population, especially in those with previous operations and adhesions.
      • Day L.W.
      • Kwon A.
      • Inadomi J.M.
      • Walter L.C.
      • Somsouk M.
      Adverse events in older patients undergoing colonoscopy: a systematic review and meta-analysis.
      Although infrequent, if any of these complications do occur, the resultant morbidity and cost can be substantial.

      Sigmoidoscopy

      Sigmoidoscopy has been studied mostly in Europe as a means to screen for CRC. The Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial included 20,726 patients who were 70 years and older. This cohort had a 20% reduction in the incidence of CRC and a 35% reduction in mortality. The NNS to prevent a case of CRC was 282.
      • Schoen R.E.
      • Pinsky P.F.
      • Weissfeld J.L.
      • et al.
      PLCO Project Team
      Colorectal-cancer incidence and mortality with screening flexible sigmoidoscopy.
      When using sigmoidoscopy as a means to screen for CRC, it is important that the bowel preparation is adequate (able to identify polyps ≥5 mm) and the splenic flexure is reached. Although the procedure can be done without sedation, the ability to reach the splenic flexure is often decreased because of patient discomfort.
      • Zubarik R.
      • Ganguly E.
      • Benway D.
      • Ferrentino N.
      • Moses P.
      • Vecchio J.
      Procedure-related abdominal discomfort in patients undergoing colorectal cancer screening: a comparison of colonoscopy and flexible sigmoidoscopy.
      Although risks are typically considered to be somewhat less than those in colonoscopy, if sedation is required, the cardiovascular risks associated with this persist. In addition, it should be noted that the right colon is not evaluated with sigmoidoscopy and thus lesions in the right side, including sessile serrated adenomas, may be missed.

      Capsule Colonoscopy

      Capsule colonoscopy is Food and Drug Administration approved for patients who have undergone previous incomplete colonoscopies requiring proximal colon imaging and in patients who are at a higher risk of colonoscopy or sedation.
      • Rex D.K.
      • Boland C.R.
      • Dominitz J.A.
      • et al.
      Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer.
      The study is limited because of issues with incomplete examinations due to poor bowel preparations.
      • Rex D.K.
      • Adler S.N.
      • Aisenberg J.
      • et al.
      Accuracy of capsule colonoscopy in detecting colorectal polyps in a screening population.
      Capsule endoscopy has not been studied in older adults. An important limitation of capsule colonoscopy is that it requires an extensive bowel preparation to be able to evaluate mucosa completely. Despite taking the bowel preparation, lesions identified subsequently require the patients to potentially undergo a second procedure, that is, colonoscopy, if anything is identified. Even though capsule colonoscopy is generally safe in the elderly, it does carry a few risks. There is still the risk of the bowel preparation and electrolyte abnormalities. In addition, there are risks of choking on the capsule, aspiration of the capsule, and developing a retained capsule due to narrowing anywhere in the gastrointestinal tract.

      Computed Tomographic Colonography

      Computed tomographic colonography is an imaging modality with a sensitivity of 82% to 92% for adenomas 1 cm or greater in size.
      • Rosman A.S.
      • Korsten M.A.
      Meta-analysis comparing CT colonography, air contrast barium enema, and colonoscopy.
      • Johnson C.D.
      • Herman B.A.
      • Chen M.H.
      • et al.
      The National CT Colonography Trial: assessment of accuracy in participants 65 years of age and older.
      Bowel preparation is still required for this study. Administration of carbon dioxide insufflates the colon through a rectal catheter. Normally, pressure in the colon is monitored to reduce the potential risk of perforation. Recommendations by the US Multi-Society Task Force (US-MSTF) still recommend proceeding with colonoscopy for those with polyps greater than 6 mm.
      • Levin B.
      • Lieberman D.A.
      • McFarland B.
      • et al.
      American Cancer Society Colorectal Cancer Advisory GroupUS Multi-Society Task ForceAmerican College of Radiology Colon Cancer Committee
      Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.
      Although the Food and Drug Administration has approved this for screening of asymptomatic patients older than 50 years,
      U.S. Preventive Services Task Force
      Screening for colorectal cancer: U.S. Preventive Services Task Force recommendation statement.
      • Levin B.
      • Lieberman D.A.
      • McFarland B.
      • et al.
      American Cancer Society Colorectal Cancer Advisory GroupUS Multi-Society Task ForceAmerican College of Radiology Colon Cancer Committee
      Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.
      this has not been specifically evaluated in older adults. The overall accuracy of the test is limited by the adequacy of the bowel preparation and the distention of the lumen. In 1 study of CT colonography in patients older than 65 years, older patients tended to have poorer insufflation with evidence of retained fluids in the colon compared with younger patients. Notably in this particular study, this did not lead to significant differences in polyp detection between the 2 groups.
      • Johnson C.D.
      • Herman B.A.
      • Chen M.H.
      • et al.
      The National CT Colonography Trial: assessment of accuracy in participants 65 years of age and older.
      Computed tomographic colonography is not without risk. The bowel preparation carries risk, exposure to radiation from the CT scan, and the risk of perforation from insufflation of air. Another potential issue associated with CT colonography is incidental findings and the subsequent need for further work-up of these findings.

      Noninvasive Modalities

      When considering any of the noninvasive modalities, the physician must first determine reasonable options for which the patient is a reasonable candidate and ensure that the patient is willing to pursue colonoscopy if the result is positive. All the noninvasive modalities are associated with false positives and lack adequate positive predictive value to diagnose cancer alone. Therefore, if a patient is not willing to consider undergoing colonoscopy after a positive test result or is in too poor health to undergo the procedure safely, then one should consider reframing the discussion around colorectal screening in general.

      Fecal Occult Blood Test

      Multiple studies with a large sample size of 50,144 older adult patients aged 70 to 80 years have found a mortality benefit when screening with FOBT. Fecal occult blood test screening is associated with an 11% to 16% reduction in mortality from CRC.
      • Mandel J.S.
      • Church T.R.
      • Bond J.H.
      • et al.
      The effect of fecal occult-blood screening on the incidence of colorectal cancer.
      Overall, the NNS to prevent 1 CRC-related death with FOBT screening in men aged 75 to 79 years was 525 and 408 in similarly aged women.
      • Ko C.W.
      • Sonnenberg A.
      Comparing risks and benefits of colorectal cancer screening in elderly patients.
      Serial FOBTs must be performed, as a single FOBT performed during digital rectal examination is not adequate for CRC screening. Unfortunately, the test is associated with a high rate of false positives (86%-98%), as there are many reasons why an individual may have small amounts of blood in stool. Although the American Cancer Society (ACS) guidelines still acknowledge its use as an acceptable modality for CRC screening,
      • Wolf A.M.D.
      • Fontham E.T.H.
      • Church T.R.
      • et al.
      Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society.
      the US-MSTF guideline has recommended against its use given the high rates of false-positive results.
      • Levin B.
      • Lieberman D.A.
      • McFarland B.
      • et al.
      American Cancer Society Colorectal Cancer Advisory GroupUS Multi-Society Task ForceAmerican College of Radiology Colon Cancer Committee
      Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.
      An FOBT is highly sensitive for any occult blood, regardless of source. Given a positive result would trigger further invasive work-up with colonoscopy, performing an FOBT in an older adult patient as a means to screen for CRC is not without risk. Therefore, caution should be exercised if one opts to screen using the FOBT and the patient should have a clear understanding of the risks associated with its use.

      Fecal Immunochemical Test

      The fecal immunochemical test is a FOBT that uses a specific antibody for human hemoglobin. The fecal immunochemical test is being used more frequently and is recommended by both the ACS guideline and the US-MSTF guideline given its improved sensitivity and specificity over FOBT.
      • Levin B.
      • Lieberman D.A.
      • McFarland B.
      • et al.
      American Cancer Society Colorectal Cancer Advisory GroupUS Multi-Society Task ForceAmerican College of Radiology Colon Cancer Committee
      Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.
      • Wolf A.M.D.
      • Fontham E.T.H.
      • Church T.R.
      • et al.
      Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society.
      One study examined the use of FIT in patients aged 50 to 69 years old but did not analyze the data based on patient age.
      • Quintero E.
      • Castells A.
      • Bujanda L.
      • et al.
      COLONPREV Study Investigators
      Colonoscopy versus fecal immunochemical testing in colorectal-cancer screening.
      In another study, FIT was compared with multi-DNA stool testing in patients 50 to 84 years of age.
      • Imperiale T.F.
      • Ransohoff D.F.
      • Itzkowitz S.H.
      • et al.
      Multitarget stool DNA testing for colorectal-cancer screening.
      In this study, the sensitivity of FIT for the detection of cancer or advanced precancerous lesions did not differ significantly according to age. Similar to an FOBT, a positive FIT result does require full colonoscopy for further evaluation, thus adding the potential risks associated with colonoscopy.

      Stool DNA Testing

      Multitarget stool DNA testing is a recent addition to the CRC screening armamentarium. In 2014 it was compared with FIT in 9989 participants, of whom 903 were 75 years and older.
      • Imperiale T.F.
      • Ransohoff D.F.
      • Itzkowitz S.H.
      • et al.
      Multitarget stool DNA testing for colorectal-cancer screening.
      In this study, the sensitivity for detecting CRC was 92.3% with stool DNA testing compared with 73.8% with FIT. The sensitivity for detecting advanced precancerous lesions was 42.4% with stool DNA testing compared with only 23.8% with FIT. However, the validity of stool DNA testing evaluated in this study is limited to the 903 patients of this study and this study was not powered to evaluate the effectiveness of stool DNA testing in the elderly. As per the ACS guideline,
      • Wolf A.M.D.
      • Fontham E.T.H.
      • Church T.R.
      • et al.
      Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society.
      this study is not recommended for those older than 85 years. That being said, stool DNA testing has a significant appeal in that it is highly sensitive for advanced polyps and is extremely safe to administer. Nevertheless, given that a positive result would require colonoscopy, patients who are not medically clear for colonoscopy should not undergo stool DNA testing.

      Blood Testing

      Septin 9 is a CRC screening marker to assess CRC. Methylated septin 9 has been found to correlate with early CRC carcinogenesis, and detecting this in blood using real-time polymerase chain reaction allows its use as a noninvasive screening test.
      • Lofton-Day C.
      • Model F.
      • Devos T.
      • et al.
      DNA methylation biomarkers for blood-based colorectal cancer screening.
      The specificity for neoplasia is reported as high as 92%.
      • Church T.R.
      • Wandell M.
      • Lofton-Day C.
      • et al.
      PRESEPT Clinical Study Steering Committee, Investigators and Study Team. Prospective evaluation of methylated SEPT9 in plasma for detection of asymptomatic colorectal cancer.
      Data from elderly patients are limited. Church et al
      • Church T.R.
      • Wandell M.
      • Lofton-Day C.
      • et al.
      PRESEPT Clinical Study Steering Committee, Investigators and Study Team. Prospective evaluation of methylated SEPT9 in plasma for detection of asymptomatic colorectal cancer.
      reported on 35 patients who were 65 years and older and found higher sensitivity and specificity in patients younger than 65 years, but this did not reach statistical significance. In the elderly, it needs to be used cautiously, as the false-positive rate increases with age. This increase can result in increased patient harms from anxiety and unnecessary invasive procedures. Finally, septin 9 testing is not a confirmatory test for colon cancer and any positive result requires follow-up with colonoscopy or other invasive diagnostic test for colon cancer. Septin 9 testing is currently not recommended by major gastroenterology societies.
      U.S. Preventive Services Task Force
      Screening for colorectal cancer: U.S. Preventive Services Task Force recommendation statement.
      • Rex D.K.
      • Boland C.R.
      • Dominitz J.A.
      • et al.
      Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer.

      Risks Associated With Screening Modalities in the Elderly

      The main risk of the noninvasive modes of screening is the false-positive rates associated with the tests. The positive test result requires further testing with colonoscopy, which then carries the risks associated with the procedure as mentioned below. In addition, however, if nothing is identified on colonoscopy after another modality returned a positive result, it is difficult to ascertain whether the negative colonoscopy result is a true negative or a false negative given the initial positive noninvasive test result. Significant patient anxiety and distress may occur as a result of the initial positive results, subsequent inconclusive results, and overtesting by clinicians to provide a higher degree of certainty.

      Colonoscopy

      Colonoscopy is associated with a number of potential complications. The bowel preparation, colonoscopy itself, and sedation used during the procedure are all associated with risks of complications. Most of the complication rates are higher in patients 65 years and older, with increasing complications associated with increasing age.
      • Day L.W.
      • Kwon A.
      • Inadomi J.M.
      • Walter L.C.
      • Somsouk M.
      Adverse events in older patients undergoing colonoscopy: a systematic review and meta-analysis.
      Bowel preparation can result in many complications. The preparation is necessary to provide an adequate visualization of the mucosa and screening for colon cancer. If bowel preparation is inadequate, procedural and anesthesia time increases and thus also increases the risks. Colonoscopy in the elderly may be more difficult, as older adults are more likely than younger patients to have poor preparations. In a 2002 study, patients older than 80 years had lower colonoscopy completion rates. This was attributed to preparation quality, with poor colonic preparations being significantly more common in the octogenarian group (16%) compared with the non-octogenarian group (4%).
      • Lukens F.J.
      • Loeb D.S.
      • Machicao V.I.
      • Achem S.R.
      • Picco M.F.
      Colonoscopy in octogenarians: a prospective outpatient study.
      • Chung Y.W.
      • Han D.S.
      • Park K.H.
      • et al.
      Patient factors predictive of inadequate bowel preparation using polyethylene glycol: a prospective study in Korea.
      Some bowel preparations (eg, oral sodium phosphate and magnesium citrate) are associated with an increased risk of renal complications in older adults
      • Markowitz G.S.
      • Stokes M.B.
      • Radhakrishnan J.
      • D’Agati V.D.
      Acute phosphate nephropathy following oral sodium phosphate bowel purgative: an underrecognized cause of chronic renal failure.
      • Uchiyama C.
      • Kato T.
      • Tomida K.
      • et al.
      Fatal hypermagnesemia induced by preoperative colon preparation in an elderly woman: report of a case.
      • Schelling J.R.
      Fatal hypermagnesemia.
      (Table 2). In addition, all options for preparation are associated with a risk of volume depletion, renal impairment, and electrolyte abnormalities. This can lead to alterations in mental status, including acute onset delirium, and falls with resultant complications in older adults. Split-dosing bowel preparations, although associated with better clearance of stool in the colon, may increase falls and cognitive changes related to early morning wake-ups and related sleep deprivation.
      Table 2Bowel Preparations and Concerns in Older Patients
      Colonoscopy preparationsComments for use in the older population
      Preferred preparation in the older population
       Polyethylene glycol (eg, Miralax, Golytely, Moviprep, and Nulytely)Considered safer because of osmotically balanced, nonabsorbable electrolyte solutions that cleanse the bowel by simple washout of the ingested fluid without significant fluid and electrolyte shifts

      Usually large volume (eg, 2-4 L), which can limit the completion of the entire preparation

      Should not be absorbed systemically
      Use with caution in the older population
       Magnesium citrate, Prepopik, Clenpiq, and SuprepIncreased renal complications compared with other formulations

      Volume depletion
       Oral sodium phosphate and oral sodium phosphate tablets (OsmoPrep)Hyperosmolar solution to draw plasma water into the bowel lumen to achieve the fluid washout—dose adjustment recommended in the elderly but rarely done clinically

      Increased renal complications compared with other formulations

      Volume depletion
      Adjuncts to bowel preparations: use with caution in the older population
       BisacodylRare reports of ischemic colitis
       MetoclopramideLimited benefits

      Tardive dyskinesia
       Direct visualization methods/invasiveFrequency (with negative findings)
       SigmoidoscopyEvery 5 y
       ColonoscopyEvery 10 y
       CT colonographyEvery 5 y
       Capsule endoscopyEvery 5 y
      Stool-based tests/noninvasive screening methods
       FOBTEvery year
       FITEvery year
       FIT-DNAEvery 1-3 y
      CT = computed tomographic; FIT = fecal immunochemical test; FOBT = fecal occult blood test.
      The procedure itself is associated with many complications. Day et al
      • Day L.W.
      • Kwon A.
      • Inadomi J.M.
      • Walter L.C.
      • Somsouk M.
      Adverse events in older patients undergoing colonoscopy: a systematic review and meta-analysis.
      reported in a systematic review that all-cause complications (ie, perforation, bleeding, cardiac, and pulmonary complications) were 25.9 per 1000 colonoscopies in patients older than 65 years and 34.8 per 1000 colonoscopies in patients older than 80 years. Although the risk of perforation during colonoscopy is overall low (1 per 100,000 colonoscopies), it is 30% higher in patients older than 65 years than in younger cohorts. Mortality is similarly low at 1 per 100,000 colonoscopies. The risk of bleeding is higher with polyp resection, which is more likely in older adults given the higher risk of adenomatous polyps.
      Completion rates vary from 78% to 86% in older adults in general and from 52% to 95% in the very old (older than 80 years).
      • Lukens F.J.
      • Loeb D.S.
      • Machicao V.I.
      • Achem S.R.
      • Picco M.F.
      Colonoscopy in octogenarians: a prospective outpatient study.
      • Karajeh M.A.
      • Sanders D.S.
      • Hurlstone D.P.
      Colonoscopy in elderly people is a safe procedure with a high diagnostic yield: a prospective comparative study of 2000 patients.
      • George M.L.
      • Tutton M.G.
      • Jadhav V.V.
      • Abulafi A.M.
      • Swift R.I.
      Colonoscopy in older patients: a safe and sound practice.
      • Schmilovitz-Weiss H.
      • Weiss A.
      • Boaz M.
      • Levin I.
      • Chervinski A.
      • Shemesh E.
      Predictors of failed colonoscopy in nonagenarians: a single-center experience.
      Unfortunately, incomplete colonoscopy is associated with higher rates of interval CRC.

      Sedation

      Multiple studies focusing on procedural sedation in older adults suggest that there is an increased risk of hypoxia, aspiration, hypotension, and arrhythmias compared with younger patients.
      • Karajeh M.A.
      • Sanders D.S.
      • Hurlstone D.P.
      Colonoscopy in elderly people is a safe procedure with a high diagnostic yield: a prospective comparative study of 2000 patients.
      • Clarke G.A.
      • Jacobson B.C.
      • Hammett R.J.
      • Carr-Locke D.L.
      The indications, utilization and safety of gastrointestinal endoscopy in an extremely elderly patient cohort.
      Most of these studies have examined use of a benzodiazepine (eg, midazolam) and a narcotic agent (eg, fentanyl). The ASGE issued the following recommendations to reduce risk associated with anesthetic use in older adults undergoing endoscopic procedures: (1) to use fewer sedative agents at doses lower than those used in younger patients and (2) to administer medications using slower infusion rates.
      Alternatively, propofol has been found to be safe and effective in older cohorts.
      • Heuss L.T.
      • Schnieper P.
      • Drewe J.
      • Pflimlin E.
      • Beglinger C.
      Conscious sedation with propofol in elderly patients: a prospective evaluation.
      The ASGE also recommends, similar to the combination of benzodiazepine and a narcotic agent, that the dose be lowered and administered slowly in the elderly.
      • Rex D.K.
      • Boland C.R.
      • Dominitz J.A.
      • et al.
      Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer.

      When Should Screening Be Discontinued and How to Discuss This With Your Patients

      A decision-making approach should be used when deciding to initiate, continue, or discontinue CRC screening in older adults. Discussions should include the risks of the screening test itself, the risks of a potential treatment(s) if CRC was detected during screening, and the risk of morbidity and mortality from CRC if present and left untreated. Patient preferences should be thoroughly explored. Stopping screening for CRC should be considered in patients who have an estimated life expectancy of less than 10 years, especially in patients who have a significant comorbidity burden that leaves them in poorer health. The discussion should be targeted to the health literacy of the individual, including decision-making aids when appropriate. Primary decision makers other than the patient (eg, health care proxy and next of kin) should be included in the discussion based on patient preference and/or if the patient lacks capacity to fully weigh the risks and benefits of this complex decision independently. Regardless of the decision made, the provider should thoroughly document details of the discussion, including the factors that have led the patient and provider to pursue screening or not (Table 3).
      Table 3Colorectal Screening in the Older Population With Screening Choices
      SocietyRecommendations for 76- to 85-y-oldRecommendations for >85-y-old
      USPSTF and the American Cancer SocietyRecommend against routine screening for colorectal cancer in adults aged 76-85 y. There may be considerations that support colorectal cancer screening in an individual patientRecommend against screening
      American College of GastroenterologyAge to stop is not specifiedNot specified
      American Gastroenterology AssociationScreening is potentially beneficial in persons up to the age of 86 y if there has not been previous screening, but should be considered in the context of comorbidities and life expectancy. Persons with previously negative screening test results, particularly negative screening colonoscopy results, could consider stopping at the age of 75 yNot specified
      American Society of Gastrointestinal EndoscopyScreening is potentially beneficial in persons up to the age of 86 y if there has not been previous screening, but should be considered in the context of comorbidities and life expectancy. Persons with previously negative screening test results, particularly negative screening colonoscopy results, could consider stopping at the age of 75 yNot specified
      American College of PhysiciansFor those older than 75 y and individuals whose life expectancy is estimated to be <10 y, screening is not recommendedNot specified
      National Comprehensive Cancer NetworkScreening should be an individual decision and can be discussed for individuals aged between 75 and 85 yNot specified
      US Multi-Society Task Force on Colorectal CancerScreening should be considered for individuals without previous screening between the ages of 75 and 85 yNot specified

      Conclusion

      Current societal guidelines suggest discontinuing colonoscopy screening at the age of 75 years and no screening for those older than 85 years. Although there is a balance between risk and benefit in colon cancer screening in the elderly, there is general consensus that an age cutoff is not the sole factor contributing to colon cancer screening decision making. Instead, balancing the risks and benefits of further screening in the older population should be between the provider and the patient, taking into account personal preferences, comorbidities, functional status, and life expectancy.

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