Review of risk factors for the development of contralateral breast cancer.

BACKGROUND Women treated for breast cancer have an increased risk for developing metachronous contralateral breast cancer (CBC). Patient perception of this risk is often overestimated and has been found to contribute to the decision to undergo contralateral prophylactic mastectomy. An individual's risk is dependent on both patient and tumor characteristics. This review examines and summarizes the current literature on the factors that affect CBC risk. DATA SOURCES English-language publications with the keyword "contralateral breast cancer" were identified through a MEDLINE literature search. CONCLUSIONS The global incidence of CBC is decreasing, a trend that is attributed to more effective adjuvant therapies. Patients with BRCA germ-line mutations demonstrate the highest risk for CBC. In the absence of known genetic mutations, patients with strong family histories who are diagnosed at young ages (<35 years) with estrogen receptor-negative index tumors appear to have a higher incidence of CBC.