Bilateral carcinoma of the breast. Epidemiology and histopathology.

A history of previous carcinoma in the contralateral breast was found in 66 of 1351 women (5%) consecutively diagnosed as having breast carcinoma. The mean time interval between the diagnosis of the first and second tumour was 10.0 years (range 0-37 years); 63 of the tumours were metachronous. No significant differences were found between the first and the second carcinoma with respect to the Ackerman malignancy grading or the frequency of axillary node involvement. High risk groups for bilateral disease could not be defined on the basis of information about familial occurrence, parity, age at first birth, or malignancy grade.