Résumé
One of the most important issues in breast cancer is the possibility of developing a new second carcinoma in the opposite breast. In order to evaluate the clinical and histopathologic characteristics of bilateral breast cancer, we retrospectively reviewed the clinical records of 23 bilateral breast cancer patients from among the 1136 women with invasive breast cancer treated in our Departmentbetween January 1989 and December 1995. Tumors were grouped into those simultaneously detected or detected within 6 months of each other, in both breasts (synchronous, 8/23) and those detected more than 6 months (metachronous, 15/23). The mean interval in the metachronous cancers was 55 months. Among the previously reported risk factors for bilateral breast cancer, such as onset at an early age, lobular histology, family history, and multicentricity, family history was the only statistically significant factor in our study(p<0.01). The most frequent histologic type of tumor was an invasive ductal carcinoma and the most frequent tumor location was the outer upper quadrant, as in unilateral breast cancer. The concordance rate of the histologic types and the location of both tumors was 60.9% and 39.1%, respectively. According to the AJCC classification, the most common pathologic stage was IIA. For tumors detected by mammography alone, the pathologic stage of the tumors was lower and the percentage of in situ lesions was higher than for those detected by physical examination. In conclusion, in breast cancer patients with a family history of breast cancer, the possibility of contralateral breast cancer should be considered more carefully, and close mammographic follow up and the concept of mirror image may be helpful in early detection of contralateral breast cancer.