Estimating Contralateral Breast Cancer Risk

Accurate estimates of contralateral breast cancer (CBC) risk are necessary around the time a first breast cancer is diagnosed to aid surgical decision-making. This review will discuss the known risk factors for contralateral breast cancer (CBC) and present methods for calculating CBC risk that can be utilized when breast surgeons counsel patients.

In addition to the well-known factors that impact contralateral breast cancer risk, such as BRCA1/BRCA2 mutation carrier status and history of chest wall radiation, other factors that affect CBC risk are being better defined. Recent studies that take into account important covariates in contralateral breast cancer risk, such as BRCA1 and BRCA2 mutation carrier status, family history, and systemic treatment, are further improving estimates of contralateral risk. Recent studies show family history, especially of breast cancer in a young relative or of bilateral breast cancer, hormone receptor status, lobular histology, and breast density are important in accurately estimating contralateral breast cancer risk. The Manchester formula, a pen and paper calculation for contralateral breast cancer risk estimation, and CBCRisk, a recently developed online CBC risk calculator, are two tools now available to clinicians.

Despite a decreasing incidence of contralateral breast cancer over the last few decades, there has been a steady increase in the number of women undergoing contralateral prophylactic mastectomy (CPM). The reasons for this are multifactorial, but fear of a contralateral breast cancer and a tendency to overestimate the risk of a contralateral breast cancer are two factors. Therefore, a critical element in decision-making for women considering CPM is having an accurate estimate of contralateral breast cancer risk. Models for estimating contralateral breast cancer risk are not widely used, but are available.