Screening for colorectal cancer.

The following comments pertain to the Best Practice Advice summarized in Figure 2 of the clinical guideline on CRC screening from Qaseem and colleagues (1). The section entitled “Harms of unnecessary screening” should have been named “Harms of screening” because these harms (or risks for harm) are present whether the screening is necessary or not. The possibility of harm caused by a “necessary” screening procedure must never be neglected by the clinician, especially when obtaining informed consent from the patient. There also was no mention of radiation exposure on the list of harms of double-contrast barium enema (DCBE). Because DCBE is performed under fluoroscopy, the radiation exposure is almost twice that of computed tomography colonography (2), although the latter provides superior sensitivity for detection of polyps (3). For that reason, the U.S. Preventive Services Task Force (USPSTF) did not include DCBE among its recommended CRC screening methods (4). The ACP guidelines also differ somewhat with the USPSTF recommendations on when to stop screening for CRC and state that screening should stop “in adults over the age of 75 years or in adults with a life expectancy of less than 10 years” (1). The USPSTF recommends against routine screening for CRC in adults aged 76 to 85 years but allows for “considerations that support colorectal cancer screening in an individual patient” (4). This subtle but important difference allows the clinician flexibility to offer CRC screening to the increasing number of health-conscious seniors in this age range who have worked hard to reduce their cardiovascular risk factors, and thus may have a longer-than-average life expectancy.