Predictors of Locoregional Recurrence After Failure to Achieve Pathologic Complete Response to Neoadjuvant Chemotherapy in Triple-Negative Breast Cancer

Background: This study evaluated factors predictive of locoregional recurrence (LRR) in women with triple-negative breast cancer (TNBC) treated with neoadjuvant chemotherapy who do not experience pathologic complete response (pCR). Methods: This is a single-institution retrospective review of women with TNBC treated with neoadjuvant chemotherapy, surgery, and radiation therapy in 2000 through 2013. LRR was estimated between patients with and without pCR using the Kaplan-Meier method. Patient-, tumor-, and treatment-specific factors in patients without pCR were analyzed using the Cox proportional hazards method to evaluate factors predictive of LRR. Log-rank statistics were then used to compare LRR among these risk factors. Results: A total of 153 patients with a median follow-up of 48.6 months were included. The 4-year overall survival and LRR were 70% and 15%, respectively, and the 4-year LRR in patients with pCR was 0% versus 22.0% in those without (P<.001). In patients without pCR, lymphovascular space invasion (LVSI; hazard ratio, 3.92; 95% CI, 1.64-9.38; P=.002) and extranodal extension (ENE; hazard ratio, 3.32; 95% CI, 1.35-8.15; P=.009) were significant predictors of LRR in multivariable analysis. In these patients, the 4-year LRR with LVSI was 39.8% versus 15.0% without (P<.001). Similarly, the 4-year LRR was 48.1% with ENE versus 16.1% without (P=.002). In patients without pCR, the presence of both LVSI and ENE were associated with an even further increased risk of LRR compared with patients with either LVSI or ENE alone and those with neither LVSI nor ENE in the residual tumor (P<.001). Conclusions: In patients without pCR, the presence of LVSI and ENE increases the risk of LRR in TNBC. The risk of LRR is compounded when both LVSI and ENE are present in the same patient. Future clinical trials are warranted to lower the risk of LRR in these high-risk patients.