We concur that flexible sigmoidoscopy has a high negative predictive value when used as a screening tool. The conclusion of our study1 is that the majority of prevalent proximal colon cancers will be missed by sigmoidoscopy as most of these lesions are not associated with a synchronous polyp detectable by standard 60-cm flexible sigmoidoscopy. If the trend in the rightward shift of distribution of colorectal cancer continues, the utility of flexible sigmoidoscopy as a screening tool will be further impaired. Recent studies have demonstrated that screening sigmoidoscopy appears to diminish colorectal cancer mortality. While the risk of colon cancer is fairly low in the general population, we simply wish to point out that physicians should emphasize that a negative screening flexible colonoscopy does not rule out malignant or potentially malignant lesions in the proximal colon. This issue should be considered when discussing results or counseling patients.
Dinning JP, Hixson LJ. Value of Flexible Sigmoidoscopy-Reply. Arch Intern Med. 1995;155(4):427. doi:10.1001/archinte.1995.00430040102015