Primary Chemoradiotherapy Treatment (PCRT) for HER2+ and Triple Negative Breast Cancer Patients: A Feasible Combination

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Abstract
Primary systemic treatment (PST) downsizes the tumor and improves pathological response. The aim of this study is to analyze the feasibility and tolerance of primary concurrent radio-chemotherapy (PCRT) in breast cancer patients. Patients with localized TN/HER2+ tumors were enrolled in this prospective study. Radiation is delivered concomitantly during the first 3 weeks of chemotherapy, and it is based on a 15 fractions scheme (40.5Gy/2.7Gy per fraction to whole breast and nodal levels I-IV. Chemotherapy is based on Pertuzumab-Trastuzumab-Paclitaxel followed by anthracyclines in HER2+ and CBDCA-Paclitaxel followed by anthracyclines in TN breast cancers patients. 58 patients were enrolled, 25 patients (43%) were TN and 33 patients HER2+ (57%). With a median follow-up of 24.2 months, 56 patients completed PCRT and surgery. A total of 35 patients (87.5%) achieved >90% loss of invasive carcinoma cell in the surgical specimen. The 70.8% and the 53.1% of patients with TN and HER-2+ subtype respectively achieved complete pathological response (pCR). This is the first study of concurrent neoadjuvant treatment in breast cancer in which three strategies are applied simultaneously: fractionation of RT in 15 sessions, adjustment of CT to tumor phenotype and local planning by PET. The pCR rates are encouraging.