Sei J. Lee, M.D., from the University of California in San Francisco, and colleagues conducted a meta-analysis using survival data from population-based, randomized, controlled trials comparing populations (aged 40 years and older) screened and not screened for breast or colorectal cancer (using mammography and fecal occult blood testing, respectively).

The researchers used five breast and four colorectal cancer screening trials to examine the estimated length of time needed after screening to observe a survival benefit. It took 3.0 years before one death from breast cancer was prevented for every 5,000 women screened and, on average, 10.7 years before one death from breast cancer was prevented for 1,000 women screened. It took 4.8 years before one death from colorectal cancer was prevented for 5,000 patients screened and, on average, 10.3 years before one death from colorectal cancer was prevented for 1,000 patients screened.

"Our results suggest that screening for breast and colorectal cancer is most appropriate for patients with a life expectancy greater than 10 years," the authors write.

Full Text