The relative risks of fatal colorectal cancer according to lifetime number of blood donations in the Health Professionals Follow-up Study (1992–2008).

1adjusted for age (in months).2adjusted for age (in months), smoking before age 30 (0, 1–4, 5–10, or >10 pack-years), history of colorectal cancer in a parent or sibling (yes, no), history of colonoscopy or sigmoidoscopy (yes, no), regular aspirin use (yes, no), body mass index (2), physical activity (3adjusted for age (in months), factors listed in model 2, consumption of processed meat (quintiles), consumption of beef, pork, or lamb as a main dish (quintiles), alcohol consumption (0–