The Influence of Repeat Surgery and Residual Disease on Recurrence After Breast-Conserving Surgery: A Danish Breast Cancer Cooperative Group Study.

Background: A significant proportion of women who have breast-conserving surgery (BCS) subsequently undergo re-excision or proceed to mastectomy. This study aimed to identify factors associated with residual disease after repeat surgery and to determine their effect on ipsilateral breast tumor recurrence (IBTR) and survival.

Methods: The study cohort was identified within the national population-based registry of the Danish Breast Cancer Cooperative Group, including women who underwent BCS for unilateral invasive breast cancer between 2000 and 2009.

Results: The study investigated 12,656 women. Within 2 months after initial BCS, 1342 (11 %) of these women had a re-excision, and 756 (6 %) of the women had a mastectomy. Residual disease was found in 20 % of re-excisions and 59 % of mastectomies. In adjusted analysis, ductal carcinoma in situ (DCIS) outside the invasive tumor, positive initial margin, and age younger than 50 years were associated with increased risk of residual disease. In the adjusted analysis, patients with residual disease after re-excision had an increased risk of IBTR regardless whether residual findings were invasive carcinoma [hazard ratio (HR), 2.97; 95 % confidence interval (CI) 1.57-5.62] or DCIS (HR, 2.58; 95 % CI 1.50-4.45). However, no difference was seen in overall survival comparing patients receiving one excision with those having repeat surgery with or without residual disease (p = 0.96).

Conclusion: A higher risk of IBTR seen after re-excision was associated with residual disease. Overall survival was similar regardless of repeat surgery and residual findings.