A More Flexible Outlook on Colorectal Cancer Screening

Published - Written by Rena Xu

At age 65, Mrs. P., a patient recently seen in clinic, had never had a colonoscopy.  She understood the rationale for undergoing colorectal cancer screening and the risks of not doing so – but year after year, when colonoscopy was offered, she chose to defer action.

For patients like Mrs. P. who shy away from screening colonoscopy, is there a different screening strategy that physicians can advocate?  A study recently published in NEJM suggests that one answer may be flexible sigmoidoscopy.  Schoen et al. report findings from a multi-center randomized, controlled trial that evaluated the effectiveness of flexible sigmoidoscopy as a screening tool.  The study randomly assigned nearly 155,000 individuals aged 55 to 74 years either to receive screening with flexible sigmoidoscopy at baseline and again after three to five years (intervention group) or to receive usual care (control group).  The mean follow-up time was 11 years, and the primary endpoint was death from colorectal cancer.  Colorectal cancer incidence was a secondary endpoint.

For both endpoints, results were significant.  Screening reduced colorectal cancer incidence by 21%; the reduction was for both distal (relative risk 0.71; P<0.001) and proximal (relative risk 0.86; P = 0.01) colorectal cancer.  Additionally, screening reduced colorectal cancer mortality by 26% (P<0.001).  This was primarily due to a 50% reduction in mortality from distal colorectal cancer (P<0.001); the difference in mortality from proximal colorectal cancer was not statistically significant between the two study groups (P=0.81).

In an accompanying editorial, Dr. John M. Inadomi of the University of Washington notes that despite the apparent effectiveness of flexible sigmoidoscopy, its use in the U.S. has significantly decreased.  This trend, he implies, warrants reconsideration.  Inadomi writes: “It should be acknowledged that flexible sigmoidoscopy reduces colorectal-cancer incidence and mortality for the portion of the colon that it is designed to examine.  Next, high-quality evidence must show the superiority of colonoscopy over other screening tests before we dismiss the use of flexible sigmoidoscopy and fecal occult-blood testing, both of which have randomized, controlled trials supporting their benefit.”

Recognizing the effectiveness of flexible sigmoidoscopy as a screening tool is particularly important if, as previous studies have suggested, patients are more likely to adhere to alternative screening strategies as compared to screening colonoscopy.  Further studies on the effectiveness of different methods for detecting different types of colorectal cancer will likely help physicians to better tailor screening recommendations to individual patients’ needs and preferences.  This could potentially improve adherence, and by extension, the value proposition of screening overall.

In the meantime, for patients like Mrs. P. with whom discussions of screening colonoscopy have made limited progress, flexible sigmoidoscopy may offer a solution with which both patient and provider are comfortable.

For what types of patients do you currently recommend flexible sigmoidoscopy over other screening methods?  How will these study findings affect your practice?