Colorectal cancer screening for older adults

In recent years evidence that the incidence of and mortality from colorectal cancer can be substantially reduced by screening has been accumulating. Strong evidence from randomised trials is available for both fecal occult blood testing1 2 3 and screening with flexible sigmoidoscopy.4 5 6 7 8 Observational epidemiological studies suggest an even larger benefit associated with screening colonoscopy.8 9 10 11 Screening for colorectal cancer is now widely recommended by expert committees and is being introduced in a rapidly increasing number of countries.

However, many unanswered questions remain about the practical details of screening for colorectal cancer, and empirical evidence to guide screening programmes is sparse. In a linked paper (doi:10.1136/bmj.h1662), Tang and colleagues ask a particularly important question about screening older adults using flexible sigmoidoscopy; specifically at what age screening would no longer be appropriate.12 Using a survival meta-analysis of flexible sigmoidoscopy trials,12 the authors estimated the time it would take for screening to achieve defined reductions in mortality from colorectal cancer and deduced that screening …