Immunohistochemical Analysis of Colorectal Cancer among Atomic Bomb Survivors in Hiroshima

In order to elucidate the biological characteristics of colorectal cancer among atomic bomb survivors in Hiroshima, a total of 159 cases of colorectal cancers comprising 73 cases in exposed atomic bomb survivors and 86 cases in non-exposed individuals were examined histologically and immunohistochemically for various functioning proteins. No statistical differences could be demonstrated in the incidence of various marker expressions of colorectal cancers between the exposed group and control group. However, comparison by the site of colorectal cancer showed that sigmoid colon cancers in the exposed group or high dose group showed a significantly higher frequency of glycoproteins such as α1-antichymotrypsin (ACT), secretory component (SC), α1-antitrypsin (AAT), and human chorionic gonadotropin (HCG) when compared with the control group. These results correlated well with the epidemiological data that the radiation effect on the incidence of colorectal cancer in atomic bomb survivors was most remarkable in the sigmoid colon.