The effect of using fecal testing after a negative sigmoidoscopy on the risk of death from colorectal cancer.

Objective: To examine whether receiving a fecal occult blood test after a negative sigmoidoscopy reduced mortality from colorectal cancer.

Methods: We used a nested case-control design with incidence-density matching in historical cohorts of 1,877,740 50-90-year-old persons during 2006-2012, in an integrated health-system setting. We selected 1758 average risk patients who died from colorectal cancer and 3503 matched colorectal cancer-free persons.