Occult malignancy in patients undergoing contralateral prophylactic mastectomy.

OBJECTIVE: To identify factors that predict for occult malignancy or high-risk lesions (HRL) in the contralateral breast among women undergoing contralateral prophylactic mastectomy (CPM).

BACKGROUND: A growing number of women are choosing to undergo CPM, yet the benefit of this procedure for the average woman with breast cancer remains uncertain. The identification of reliable predictors of occult malignancy or HRL in the contralateral breast may aid in selecting patients most likely to benefit from CPM.

METHODS: Patients undergoing mastectomy with CPM for their first diagnosis of unilateral stage 0 to III breast cancer were retrospectively identified (1997-2005). Univariate and multivariate logistic regression was used to identify factors predictive of HRL and/or occult contralateral breast cancer (CBC).

RESULTS: Among 2965 patients, 407 (13%) underwent CPM. Occult CBC was identified in 24 (6%) patients, and 114 (28%) had an HRL. On univariate analysis, multifocality/multicentricity of the index cancer was the only factor associated with occult malignancy in the CPM (OR 2.88, P = 0.04). On multivariate analysis, patient age and progesterone receptor positivity of the index cancer were associated with finding either malignancy or a HRL in the CPM.

CONCLUSIONS: The diagnosis of multifocality/multicentricity invasive index cancer was associated with occult malignancy in the CPM; however, lack of standardized definitions and differences in pathologic evaluation limit the application of this finding in the preoperative setting. Until reliable predictors for occult disease are identified, the low rates of occult CBC do not support the use of CPM in average-risk women with newly diagnosed breast cancer.