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

SIMPLE SUMMARY: The aim of this study is to analyze the feasibility and tolerance of primary concurrent radio–chemotherapy in breast cancer patients. The primary systemic treatment of breast cancer aims to limit the scope of subsequent surgery by reducing the size of the tumor allowing for less extensive surgery, improved cosmetic outcomes, and reduced postoperative complications. We enrolled 58 patients with triple negative and HER-2 amplified breast cancer who were treated for three weeks with radiotherapy and concurrent chemotherapy. The 70.8% of patients with triple negative and the 53.1% of patients with HER-2 amplified achieved complete pathological response. In conclusion, primary concurrent radio–chemotherapy is feasible, with acceptable tolerance and high rates of pathological response. 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 was delivered concomitantly during the first 3 weeks of chemotherapy, and it was based on a 15 fractions scheme, 40.5 Gy/2.7 Gy per fraction to whole breast and nodal levels I-IV. Chemotherapy (CT) was based on Pertuzumab–Trastuzumab–Paclitaxel followed by anthracyclines in HER2+ and CBDCA-Paclitaxel followed by anthracyclines in TN breast cancers patients. A total of 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 cells 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 were applied simultaneously: fractionation of RT (radiotherapy) in 15 sessions, adjustment of CT to tumor phenotype and local planning by PET. The pCR rates are encouraging.