Sugiyama H, et al. – Researchers assessed 105,444 atomic bomb survivors to examine the impact on radiation on colorectal cancer rates—adjusted for smoking status, alcohol intake, meat intake frequency, and body mass index by anatomical subsite (proximal colon, distal colon, and rectum). They used Poisson regression methods to describe radiation-associated excess relative risks (ERR) and excess absolute rates for the 1958-2009 period. They identified nearly 3,000 first primary colorectal cancers (871, and 1,046 proximal, distal, and rectal cancers, respectively). An increased risk of proximal and distal colon cancers was reported in relation to ionizing radiation. The ERR for proximal cancer persisted over time, but that for distal colon cancer decreased. There was no indication of radiation effects on rectal cancer incidence in this population. Subsite-specific cancer background rates were reported in relation to smoking, alcohol intake and body mass index.