Contralateral Breast Cancer Risk in Women with Ductal Carcinoma In Situ: Is It High Enough to Justify Bilateral Mastectomy?

Abstract

Background

Women with DCIS are increasingly choosing bilateral mastectomy. We sought to quantify rates of contralateral breast cancer (CBC) and ipsilateral breast tumor recurrence (IBTR) after breast-conserving surgery (BCS) for DCIS, and to compare risk factors for CBC and IBTR.

Methods

From 1978–2011, DCIS patients undergoing BCS with a contralateral breast at risk were identified from a prospectively maintained database. Association of clinicopathologic and treatment factors with CBC and IBTR were evaluated using Kaplan-Meier analysis and competing risk regression (CRR).

Results

Of 2759 patients identified, 151 developed CBC and 344 IBTR. 5- and 10-year Kaplan-Meier CBC rates were 3.2% and 6.4%. Overall, 10-year IBTR rates were 2.5-fold higher than CBC rates, and without radiation, 4-fold higher. On CRR, 5- and 10-year rates were 2.9% and 5.8% for CBC, and 7.8% and 14.5% for IBTR. CBC risk (Kaplan-Meier and CRR multivariable analysis) and invasive CBC risk (CRR multivariable analysis) were not significantly associated with age, family history, presentation, nuclear grade, year of surgery, or radiation. By Kaplan-Meier, endocrine therapy was associated with lower CBC risk (HR 0.57, p=0.03). 10-year risk of subsequent CBC in the subset of patients who developed IBTR was similar to the cohort as a whole (8.1% vs. 6.4%).

Conclusions

Rates of CBC were low across all groups, including those who experienced IBTR. CBC was not associated with factors that increase IBTR risk. While factors associated with IBTR risk are important in decision-making regarding management of the index DCIS, they are not an indication for contralateral prophylactic mastectomy.