Predictors of Contralateral Breast Cancer in Patients With Unilateral Breast Cancer Undergoing Contralateral Prophylactic Mastectomy

BACKGROUND: Although contralateral prophylactic mastectomy (CPM) reduced the risk of contralateral breast cancer in unilateral breast cancer patients, it was difficult to predict which patients were most likely to benefit from the procedure. The objective of this study was to identify the clinicopathologic factors that predict contralateral breast cancer and thereby inform decisions regarding performing CPM in unilateral breast cancer patients. METHODS: A total of 542 unilateral breast cancer patients who underwent CPM at The University of Texas M. D. Anderson Cancer Center from January 2000 to April 2007 were included in the current study. A logistic regression analysis was used to identify clinicopathologic factors that predict contralateral breast cancer. RESULTS: Of the 542 patients included in this study, 25 (5%) had an occult malignancy in the contralateral breast. Eighty-two patients (15%) had moderate-risk to high-risk histologic findings identified at final pathologic evaluation of the contralateral breast. Multivariate analysis revealed that 3 independent factors predicted malignancy in the contralateral breast: an ipsilateral invasive lobular histology, an ipsilateral multicentric tumor, and a 5-year Gail risk >= 1.67%. Multivariate analysis also revealed that an age >= 50 years at the time of the initial cancer diagnosis and an additional ipsilateral moderate-risk to high-risk pathology were independent predictors of moderate-risk to high-risk histologic findings in the contralateral breast. CONCLUSIONS: The findings indicated that CPM may be a rational choice for breast cancer patients who have a 5-year Gail risk >= 1.67%, an additional ipsilateral moderate-risk to high-risk pathology, an ipsilateral multicentric tumor, or an ipsilateral tumor of invasive lobular histology. Cancer 2009;115:962-71. (c) 2009 American Cancer Society.