Abstract 5639: Preoperative concurrent paclitaxel and radiation in locally advanced breast cancer (LABC): Five-year outcomes on 105 patients

Abstract

Abstract Purpose: A prospective trial of preoperative concurrent paclitaxel and radiation for patients with LABC was conducted at three academic institutions. Five-year local and systemic control rates are reported. Patients and Methods: 105 patients with LABC were treated with concurrent neoadjuvant paclitaxel and radiation. Paclitaxel was administered at 30 mg/m2 intravenously twice a week for 10-12 weeks. Daily radiotherapy was delivered to the breast, axillary and supraclavicular lymph nodes during weeks 2-7, at 1.8 Gy per fraction to a total dose of 45 Gy followed by a boost of 14 Gy at 2 Gy per fraction to the originally palpable tumor. Weekly trastuzumab (2mg/kg) was added for 8 more recent patients whose tumor over-expressed Her-2/neu. At one of the three institutions preoperative paclitaxel (3 cycles of 175 mg/m2 q 3 weeks) was also administered prior to chemo-radiation to 36 patients. Pathologic response was defined as complete response (pCR) in the absence of invasive cancer in breast or lymph nodes; partial response (pPR) as the persistence of < 10 microscopic foci of invasive carcinoma in breast or lymph nodes. After surgery additional systemic therapy was left to the discretion of the treating physician. Results: Pathological response (pCR and pPR) after neoadjuvant chemo-radiation was achieved in 36/105 patients (34.3%, 95% confidence interval: 25.3% - 44.2%). 30/105 patients underwent breast-conserving surgery after neoadjuvant chemo-radiation (28.6%), while 74 underwent mastectomy. One patient progressed during therapy and did not undergo surgery. With a median follow up of 60 months and a maximum of 137 months, the median survival has not been reached. The estimated 5-year overall cumulative survival (OS) is 71.6% (95% confidence interval: 60.5% - 80.1%). Local recurrence occurred in 4/105 patients (3.8%): in 3/4 synchronously with or following systemic recurrence. Five patients (4.8%) developed contra-lateral breast cancer. Patients without a pathologic response had a higher risk of recurrence or death than patients who had a pathologic response (hazard ratio = 2.86, logrank p-value=0.009); similarly, survival was shorter (hazard ratio = 4.28, logrank p-value=0.003). The 5-year estimated OS for non-responders was 61.6% compared with 87.9% for responders. A separate analysis of patients who received additional preoperative paclitaxel before chemo-radiation showed a pathologic response rate of 41.7% (15/36 patients, 95% confidence interval: 25.5% to 59.2%); with an estimated 5-year OS of 63.9% (95% confidence interval: 46.1% - 77.2%). Conclusion: This series of 105 patients with LABC treated with concurrent paclitaxel and radiation demonstrated a 71.6% 5-year OS and 96% local control rate. Pathological response to concurrent paclitaxel and radiation was associated with a significantly better 5-year survival. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5639.