Assessing the Effect of Lifetime Contralateral Breast Cancer Risk on the Selection of Contralateral Prophylactic Mastectomy for Unilateral Breast Cancer.

INTRODUCTION: Contralateral prophylactic mastectomy (CPM) rates are rising, with fear implicated as a contributing factor. This study used a contralateral breast cancer (CBC) risk stratification tool to assess whether the selection of CPM is reflective of future CBC risk.

PATIENTS AND METHODS: This retrospective study evaluated 404 women with unilateral breast cancer treated with breast conservation, unilateral mastectomy, or bilateral mastectomy within a single multidisciplinary clinic. Women were evaluated by the Manchester risk tool to calculate lifetime CBC risk. Logistic regression analysis was used to evaluate whether CBC risk was associated with CPM, and the clinical rationale for prophylactic mastectomy justification was recorded.

RESULTS: Sixty-two percent underwent breast conservation, 18% unilateral mastectomy, and 20% bilateral mastectomy. In the CPM cohort, 36% had > 20% calculated lifetime CBC risk. In the invasive cohort, younger age (odds ratio 2.65, P < .0001) and genetic mutation positivity (odds ratio 35.39, P = .019) independently predicted CPM. Other contributing factors included benign contralateral breast findings (29%) and recommendations against breast conservation due to disease burden (28%). Six percent selected CPM as a result of an unsubstantiated fear regarding breast cancer.

CONCLUSION: The majority of women (63%) who selected CPM had < 20% CBC risk. In these lower-risk women selecting CPM, factors increasing reasonable fear dominated surgical choice (81% of this subset).