P5-19-14: Platinum-Based Chemotherapy in Triple-Negative Breast Cancer.

Background: There is increasing evidence that DNA repair defects characteristic of BRCA1-related cancers and triple negative breast cancer (TNBC) confer sensitivity to certain chemotherapeutic agents, such as platinums. However, prospective and retrospective studies comparing the efficacy of these agents versus conventional treatment in TNBC are lacking. The aim of this study was to evaluate the efficacy of platinum-based chemotherapy (PBC) in metastatic TNBC in terms of median duration of treatment and overall-survival (OS) and compare it to patients treated with conventional chemotherapy. Methods: We performed a retrospective chart review of patients with metastatic TNBC who received PBC from January 2007 to June 2010 treated at the Sunnybrook Odette Cancer Center and the Ottawa Hospital Cancer Centre. This cohort was compared to a control group that included metastatic TNBC treated with conventional agents that included anthracyclines, taxanes, capecitabine, and vinorelbine. Results: A total of 166 metastatic TNBC patients were analyzed: 60 treated with PBC and 106 managed with conventional treatment. Median age at diagnosis was 48 years and distant disease-free interval was 26 months (m) for both groups. Patients on both groups had multiple sites of metastases at diagnosis of recurrence than a single site of metastasis (69% for both groups). Of the 60 patients treated with PBC, 90% received a combination regimen, most commonly weekly cisplatin plus gemcitabine in 37% of patients and cisplatin plus vinorelbine in 17% of patients. The median number of cycles delivered was 4 (1-24). 33% received the PBC as first-line treatment, 38% as second-line, 18% as third-line, 7% as fourth line, and 3% as fifth-line. Only 8 patients (5%) discontinued PBC secondary to toxicity. The median time on treatment in first, second and third-line therapy was longer for the PBC group compared to the conventional group (5 vs. 2 m, p=0.108; 5 vs. 2 m, p=0.01; and 4 vs. 1 m, p=0.026). Patients treated with PBC had a longer OS compared to those managed conventionally (16 vs. 10 m, p=0.039). Conclusions: PBC appears to improve clinical outcomes in patients with metastatic TNBC compared to those treated with conventional chemotherapy regimens. Although this is a retrospective study with its obvious limitations, it adds to the growing body of literature, suggesting the benefit of PBC in TNBC. Prospective trials are needed to confirm its benefit in order to integrate it as part of the routine management of these patients. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-19-14.