10-year outcomes of breast cancer patients with histologically confirmed axillary lymph node metastases and pathologic complete response after primary systemic chemotherapy.

Abstract

1017 Background: Pathologic complete response (pCR) of tumors in the breast and axillary lymph nodes (ALN) after primary systemic chemotherapy (PST) is associated with an excellent outcome. A previous analysis showed superior 5-year overall survival (OS) and relapse-free survival (RFS) for patients who achieved an ALN pCR after PST compared to those without a pCR in 5 prospective clinical trials. This study is an expanded analysis of all patients treated with PST at our institution examining the impact of ALN pCR on 10-year OS and RFS. Methods: Patients with clinical stage II/III and pathologically confirmed ALN metastases who underwent PST were categorized into 1 of 2 groups: ALN pCR and ALN residual disease. Additional data were collected, including breast cancer subtype, clinical tumor size, and lymph node staging, pathologic tumor (T) stage, and class of PST. RFS and OS were estimated by the Kaplan-Meier product limit method. Subset analyses were performed on patients with HER2-positive cancer. Results: 1,600 women diagnosed between 1989 and 2007 were identified. Median follow-up was 79 months (5-277); 454 (28.4%) achieved an ALN pCR. ALN pCR was associated with triple-negative and higher grade cancers, lower clinical stage, and lower pathologic breast T stage. 5-year OS and RFS estimates were similar to prior analysis. The 10-year OS was 85% and 58% and the 10-year RFS 83% and 55% (p < 0.001), for patients who achieved an ALN pCR and those with residual ALN disease. For HER2-positive breast cancers, 67.3% of patients who received HER2-targeted therapy achieved an ALN pCR vs. 32.3% without HER2-targeted therapy (p < 0.001). For patients receiving HER2-targeted therapy for HER2-positive breast cancer (n = 153), the 10-year OS was 92% and 52% (p = 0.006), and the 10-year RFS was 89% and 59% (p < 0.001) for those with and without an ALN pCR. Conclusions: ALN pCR is an excellent early surrogate marker for long-term outcome, 10-year RFS and OS. In HER2-positive breast cancers, HER2-targeted therapy is associated with high rates of pCR. Despite the aggressive nature of their disease, patients who achieve ALN pCR with PST have an excellent 10-year prognosis.