Outcomes after breast-conserving surgery or mastectomy in patients with triple-negative breast cancer: meta-analysis

Background: In patients with triple-negative breast cancer (TNBC), oncological and survival outcomes based on locoregional treatment are poorly understood. In particular, the safety of breast-conserving surgery (BCS) for TNBC has been questioned. Methods: A meta-analysis was performed to evaluate locoregional recurrence (LRR), distant metastasis (DM), and overall survival (OS) rates in patients with TNBC who had breast-conserving surgery versus mastectomy. Estimates were pooled in random-effects analysis. The effect of study-level co-variables was assessed by univariable metaregression. Results: Fourteen studies, including 19 819 patients operated for TNBC met the inclusion criteria; 9828 patients (49.6 per cent) underwent BCS and 9991 (50.4 per cent) had a mastectomy. Patients with smaller tumours were more likely to be selected for BCS (pooled odds ratio (OR) for T1 tumours 1.95, 95 per cent c.i. 1.64 to 2.32; P<0.001). The pooled OR for LRR was 0.64 (0.48 to 0.85; P = 0.002), indicating a statistically significantly lower odds of LRR among women who had BCS relative to mastectomy. The pooled OR for DM was 0.70 (0.53 to 0.94; P = 0.02), indicating a lower odds of DM among women who had BCS; however, this difference diminished with increasing study-level age and follow-up time. A pooled hazard ratio of 0.78 (0.69 to 0.89; P<0.001) showed a significantly lower hazard for all-cause mortality among women undergoing BCS versus mastectomy. Conclusion: These results should be interpreted cautiously owing to likely differences in selection for BCS or mastectomy in the included studies. Patients with TNBC selected for BCS do not, however, have a worse prognosis than those treated with mastectomy, and breast conservation can be offered when feasible clinically.