Colorectal Screening and Advancing Age
Abstract & Commentary
By Malcolm Robinson, MD, FACP, FACG, AGAF, Emeritus Clinical Professor of Medicine, University of Oklahoma College of Medicine, Oklahoma City; Dr. Robinson reports no financial relationship to this field of study.
Synopsis: Advancing age was inversely related to the frequency of colorectal cancer screening, but even severe comorbidity did not seem to proportionally decrease colorectal cancer screening.
Source: Walter LC, et al. Impact of age and comorbidity on colorectal cancer screening among older veterans. Ann Intern Med 2009;150:465-473.
In general, guidelines for colorectal cancer screening include the recommendation that screening continue until age 75 in generally healthy individuals or until life expectancy is thought to be less than 5 years. The 5-year figure is used since the benefits of screening are not observed until at least 5 years after screening (at least, this is the case with stool testing for fecal occult blood). The point of the present study was to evaluate a large VA patient population to assess whether screening was being targeted to healthy older persons with substantial life expectancies.
Of an initial cohort of approximately 69,000 VA patients older than age 70, patients with incomplete data were eliminated as were those with a previous history of colitis, colorectal cancer, colon polyps, colectomy, or colostomy. Patients also were excluded who had undergone colonoscopy or barium enema within 5 years. Any diagnosis suggesting ongoing lower gastrointestinal disease was also eliminated (e.g., iron deficiency anemia, abdominal pain, weight loss, or change in bowel habits). Thus, this was intended to be a true screening population. After exclusions, 27,068 patients remained for analysis. As has been true with other VA studies, 96% of the patients were male and 87% were Caucasian. A validated scoring system was used to assess comorbidities (Charlson-Deyo scores).
Seventy-seven percent of patients had fecal occult blood testing as their initial screening modality, 13% had colonoscopy, 8% had sigmoidoscopy, and 2% had barium enema. Fewer than half of veterans 70 years of age or older received colorectal cancer screening during the 2-year period from 2001 through 2002, despite strong VA recommendations that such screening be done. For example, only 47% of patients without comorbidity were screened despite their high probability of living longer than 5 years. Conversely, on the low end, a surprising 34% of patients age 80 or older with severe comorbidities were screened. The strongest predictor of screening was number of outpatient visits to VA clinics.
The authors admit several potential weaknesses to this study. Although diagnoses were carefully assessed in the period prior to colorectal cancer screening, some patients may have had evaluation for symptoms or signs of disease that had not been recorded. In conclusion, this study suggests that colorectal cancer screening could be better targeted to healthy elderly patients with a reasonable (> 5 years) life expectancy. Patients with serious comorbidities who are unlikely to have a 5-year life expectancy generally should be excluded from routine colorectal cancer screening programs. One strength of this study was the actual determination of 5-year mortality rates in this population; this assessment revealed that true incidence of death was quite close to predicted values.
Commentary
Colorectal cancer screening has strong advocates, certainly including the gastroenterologists and surgeons who perform colonoscopies. The perfect way to accomplish screening remains to be defined. The present study included fecal occult blood testing despite the fact that this test is relatively insensitive and nonspecific. Likewise, barium enemas and sigmoidoscopies are certainly far less effective screening modalities than colonoscopy (at least, when the latter is performed by a highly competent examiner). CT colonography, not discussed in this study, remains highly controversial (radiologists in favor and endoscopists generally opposed). Although there is little doubt that colonoscopy with polypectomy can decrease the incidence of subsequent colon cancer, it is less certain that overall mortality is impacted. All of the screening modalities are relatively unpopular, and much of the failure to screen more of the eligible patients in the present study may have been due to the unwillingness of patients to participate. On the other hand, the apparently frequent screening of elderly patients with multiple comorbidities is to be deplored since such screening is not recommended by any of the GI organizations or the American Cancer Society. The correlation of screening with multiple VA clinic visits is really not all that surprising. Patients who are actively involved with physicians on a regular basis are more likely to be selected for screening and also more likely to agree to participate. One advantage of a VA study is that it eliminates the financial constructs that ordinarily would impact the selection of screening modalities and patients' willingness to have these performed. Nevertheless, even in the virtually "free" VA setting (free to patients), the screening selection process and screening execution are still imperfect.
Advancing age was inversely related to the frequency of colorectal cancer screening, but even severe comorbidity did not seem to proportionally decrease colorectal cancer screening.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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