[Bilateral breast carcinoma]

Out of 4,777 cases of female breast carcinoma operated at the Cancer Institute Hospital, Tokyo from 1946 to 1980, 170 cases, 3.56% had bilateral breast carcinoma. According to our criteria, 157 cases (92. 3%, 3.29%) were classified as primary and 103 cases (7.6%, 0.27%) were metastatic. Our criteria depend upon the histological proof whether intraductal cancer parts in the smaller or in the second cancer exist or not. Out of 157, 48 cases (1.01%) were simultaneous (within one year) and 109 cases (2.28%) were subsequent bilateral carcinoma cases. The clinical characteristics of primary bilateral breast carcinoma were earlier onset, earlier stage and better prognosis than those of unilateral cases. From the epidemiological point of view, bilateral cases showed high percentage in sterile case and familial disposition. In so called breast cancer family, bilateral cases were common and the tendency of earlier onset in succeeding generation was recognized. The annual incidence rate of bilateral breast carcinoma among amputated patients for unilateral carcinoma was calculated as 4%. So it is well said that the incidence of breast carcinoma among Japanese women is as low as one-sixth of that of Americans, but the rate of bilaterality is high and almost the same as Americans.