Evolving perspectives in contralateral breast cancer.

Despite extensive publications reviewing contralateral breast cancer (CBC), the role of screening and preventative measures for contralateral tumours is controversial and optimal clinical management remains undefined. This paper addresses the incidence, the predisposing factors, the prevention and the treatment of bilateral breast cancer based on a review of the literature. Risk factors for CBC include young age at primary breast cancer diagnosis, hereditary breast cancer (due to a germline mutation), familial breast cancer (one or more affected relatives), radiation exposure at a young age, lobular carcinoma in situ (LCIS), lobular invasive carcinoma and multicentricity. Retrospective studies suggest that contralateral mammographic surveillance results in the early detection of breast cancer, but no clear survival benefit has been demonstrated. Trials of adjuvant tamoxifen in breast cancer patients have shown a reduction in the incidence of CBC in both pre- and postmenopausal women. In addition, breast cancer patients treated with ovarian ablation and prednisone have significantly reduced CBC versus controls. In patients with primary breast cancer there is no evidence that contralateral breast biopsies or contralateral prophylactic mastectomy reduce mortality. Randomised, prospective trials to determine optimal surveillance, prevention and treatment strategies for the contralateral breast in breast cancer patients have not been conducted. Based on the published literature, contralateral breast surveillance in breast cancer patients reasonably includes breast self-examination, regular physical examinations and annual mammography. In women who have no evidence of distant metastasis at the time of CBC diagnosis, we recommend that the CBC be treated in the same manner as a first breast cancer, taking into account prior local and systemic therapy.