Abstract P4-16-14: Salvage Radiotherapy and Cisplatin for Triple Negative Breast Cancer: A Multi-Centre Study

Abstract Background/Rationale: Patients with locally advanced, triple negative(TN) breast cancer may undergo neo-adjuvant chemotherapy(NAC) prior to definitive surgery. For tumours that demonstrate progression during NAC or rapid recurrence, the optimal second-line or ‘salvage’ therapy is not well defined. Purpose: To examine the efficacy and toxicity of salvage radiotherapy (XRT) and Cisplatin(CDDP) in patients with locally advanced, triple-negative breast cancer. Methods: A retrospective review of LABC databases was performed at 3 quaternary cancer centres to identify patients with TN disease who had salvage XRT +/− CDDP. (Local research ethics board approval was obtained at each centre independently.) Patient demographics, initial staging information and primary pathology reports were reviewed to confirm eligibility. Details of NAC and salvage treatments were collected. Clinical tumour response was determined by physical assessments and imaging and categorized retrospectively using standardized definitions of response and progression. Pathological response was evaluated in all cases if available. Toxicity, loco-regional control, distant disease progression and survival were assessed up to the last available follow-up and reported. Patients who underwent previous XRT were excluded. Results: 12 patients who underwent salvage treatment were identified. All patients had TN, LABC, including 10 patients with invasive ductal carcinoma; 1 metaplastic carcinoma; 1 poorly differentiated carcinoma with neuroendocrine features. The most common indications for salvage treatment were tumour progression during NAC (n = 6) and loco-regional recurrence shortly after NAC and mastectomy (n = 3). The median age was 48 (range, 30–85). 9 patients underwent concurrent XRT + CDDP; 3 patients had salvage radiotherapy only due to poor performance status or co-morbidities. Cisplatin was administered weekly, median dose was 30mg/m2 (range, 25–40mg/m2). Median XRT dose was 65 Gy (range, 50–70 Gy) with 5 patients receiving a BID hyper-fractionated regimen. The median follow-up duration was 8 months (range, 2–60 months). 11 of 12 patients demonstrated a partial or complete clinical response to XRT +/− CDDP. 4 out of 8 patients who had surgery following salvage treatment achieved a complete pathological response (pCR). All patients developed grade 2 or 3 radiation dermatitis. No grade 4–5 toxicity was observed. One patient missed one cycle of CDDP due to grade 1 thrombocytopenia. At the last available follow-up, 4 patients were deceased or developed distant metastasis, 5 patients were alive with no evidence of disease, 3 patients had partial tumour response with surgery pending. Conclusions: Patients with locally advanced, triple-negative breast cancer who progressed during or shortly after NAC had a high clinical response rate when treated with salvage XRT+ CDDP. In patients who underwent surgery after salvage treatment, 50% achieved pCR. Salvage treatments appeared to be relatively well tolerated and safe. This subset of patients is at very high risk for tumour recurrence. Prospective, multi-centre studies of concurrent cisplatin and radiotherapy in the setting of locally advanced, triple negative breast cancer are needed to further assess efficacy and toxicity. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-16-14.

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