Women with breast cancer: Histologic findings in the contralateral breast

PURPOSE: To investigate contralateral breast biopsy histologic findings in women with breast cancer. MATERIALS AND METHODS: Histologic findings in 237 patients with breast cancer who underwent contralateral breast biopsy for clinically or mammographically detected abnormalities were retrospectively reviewed. Malignant findings were categorized by histologic type. Benign findings were categorized by risk of breast cancer. Comparison was made with mammographically guided breast biopsy results in 1,294 patients without breast cancer. RESULTS: Of the 237 patients, 168 (70.9%) had either malignancy or high-risk histologic findings. One hundred thirty-nine patients (58.6%) had malignant findings; 98 (41.4%) had benign findings. Of the 98 with benign findings, 29 (30%) had highrisk histologic findings. Thirty (33%) of the 91 patients with invasive cancer had invasive lobular carcinoma. Forty-seven (45.6%) of the 103 patients with malignant lesions at mammographically guided biopsies had ductal carcinoma in situ alone. CONCLUSION: Compared with biopsy in women without breast cancer, contralateral biopsy in women with breast cancer was more likely to show malignancy, invasive lobular carcinoma, or ductal carcinoma in situ alone (P < .001) or to show highrisk histologic benign findings (P < .001). Mammographic and clinical findings in the contralateral breast should be regarded as more suspicious than those in patients without known breast cancer.