[The relative risk of a multiple primary cancer occurrence].

Patients diagnosed with cancer of the stomach, colon, breast, and uterus at Kanagawa Cancer Center have been studied for the possibility of having multiple primary cancers. The total occurrence rates of a second primary cancer were 3.2% in men and 4.0% in women. The relative risk (RR) of man with cancer of the stomach showed a significantly heightened chance of developing cancer of colon (RR, 4.2), and women with cancer of the breast for developing cancer of lung (4.2) and of the opposite breast (8.5). Further women with an endometrial cancer had a high risk for developing a cancer of ovary (30.0).