Abstract
In 1746 cases operated on for breast cancer at the department in a recent 28-year period from 1963 to 1990, 61 cases (3.5%) had bilateral breast cancers.
When synchronous bilateral breast cancer is defined as bilateral cancers were operated on at a interval within one year, 17 cases had synchronous and 44 had heterochronous cancers. Average age was 51.6 years in synchronous patients group, versus 46.8 years for the first cancer and 55.8 years for the second in heterochronous patients group. When histologic malignancies are scored according to Bloom & Richardson, the difference between right and left cancers was as small as 0.88 for synchronous or 1.18 for heterochronous group, the similarity of histologic malignancy between right and left cancers being demonstrated. In terms of ploidy pattern and the expression of c-erbB-2 protein, the similarity of bilateral cancers was observed in 66.7% and 75.0%, respectively.
The 5-year survival rate of the patients with bilateral breast cancer was almost the same as those with unilateral breast cancer. The patients who did not receive Tamoxifen after the operation had 2.8 times the average risk of developing 2nd breast cancer as compared with those receiving Tamoxifen.
