Bilateral breast cancer. Biopsy of the opposite breast

The bilateral nature of breast cancer is becoming increasingly evident. Recently 455 patients treated by the extended radical mastectomy more than 10 years ago were reviewed. Nine percent of the original patients had developed a clinically apparent cancer in the second breast within that time interval; this corresponds to 15% of the surviving patients. Since the stage of disease at the time of primary surgical therapy is the most important prognostic factor, it is imperative to detect these lesions as early as possible when they are most apt to be localized to the breast. Although some simultaneous, second primary breast cancers can be diagnosed clinically or by mammography, the great majority are not detected by these methods at the time of primary therapy of the dominant primary cancer. We have performed contralateral breast biopsy at the time of primary surgery for a known breast cancer in one breast routinely for the last 12 years. Twelve and one half percent of the contralateral breasts biopsied contain carcinoma, most at the “minimal” stage. A total of 954 biopsies were performed in 1204 patients. In 28 cases, carcinoma was suspected in the second breast on the basis of positive preoperative physical and/or mammographic findings. Twenty of these lesions proved to be infiltrating cancers, two non‐infiltrating cancers, and six were benign. In 625 patients, equivocal thickenings or densifications were noted in the opposite breast; 74 carcinomas were found in these breasts after biopsy of the dominant thickening, with 30 infiltrating and 44 noninfiltrating cancers. In 301 patients, no abnormal findings were noted in the opposite breast, either by mammogram or physical examination. Twenty‐three cancers were detected in this group by contralateral biopsy, five infiltrating and 18 noninfiltrating. This gives a total of 119 cancers found in the second breast by 954 biopsies in 1204 patients: 12.5% simultaneous bilateral breast cancer in the patients whose second breast were biopsied, and 10% simultaneous bilateral breast cancer in the overall group. Furthermore, 10% of the benign biopsies of the second breast demonstrated atypical ductal or lobular hyperplasia, a precancerous lesion. Further follow up of these patients at 6 years demonstrates on 8.8% incidence of subsequent development of breast cancer. Biopsy of the contralateral breast at the time of initial mastectomy has detected a significant number of minimal breast cancers, most being detected before diagnosis was possible by careful physical examination or adequate mammographic examination. The technique of contralateral breast biopsy is described; when a suspicious area or dominant thickening is present in the second breast, this is excised widely. Otherwise, in the absence of any specific finding, a large segment of breast tissue, including 20 to 25% of the breast parenchyma, is excised from the tail of the breast, as well as the mirror image location of the dominant cancer, in order to afford sufficient material for adequate histopathologic examination. When bilateral breast cancers are diagnosed by positive preoperative physical or mammographic signs, the second primary lesion is not at a particularly early stage of development; 20 of 22 cancers found were infiltrating and 45% of them had positive axillary nodes. However, the occult cancer found by contralateral biopsy in the absence of positve preoperative findings were almost universally at a “minimal” stage: 60% noninfiltrating cancer, and only 8.5% of the infiltrating cancers had positive axillary nodes, usually of a minimal degree. Contralateral breast biopsy at the time of mastectomy for a known cancer represents an additional method for the early detection of carcinoma in a very high risk group.