Postmastectomy Electron Beam Radiation Therapy (Pmert): Efficacy And Toxicity

This study evaluates loco regional control and survival after mastectomy according to the initial tumor characteristics, treatment received, and also the acute and late toxicity according to the comorbidities, in patients irradiated to the chest wall previously published PMERT. We included all women irradiated after mastectomy for not metastatic breast cancer with PMERT between 2007 and 2011 in our Institute. Previously reported technique using mostly electrons was evaluated in terms of efficacy and toxicity. Acute esophageal, lung and skin toxicity were assessed retrospectively using CTCAE v.3.0. A clinical exam was weekly performed during radiation therapy and 1 and 3 months following the completion of radiation therapy. Quantitative and qualitative data were described respectively as means and proportions. Statistical comparisons were computed using X2 or Fischer’s exact test for categorical data. Recurrence free survival (RFS) was defined as the time between the end of treatment and the date of recurrence or death. Overall survival (OS) was the same but recurrences were not taken into account. Patients who didn’t experiment any event were censored at the date of last news. Among the 796 women included, 51.3% had multifocal lesions, 10.1% a triple negative (TN) status and 18.8% a HER2+ positive status; 196 (24.6%) received a neoadjuvant chemotherapy (CT), and 208 (26.1%) a systemic therapy during radiation therapy (CT and/or targeted therapy); 514 (64.6%) had at least one positive lymph node (LN). Internal mammary chain (IMC) was treated in 85.6% of cases, supraclavicular LN in 88.3% of cases, infraclavicular LN in 77.9% of cases and axilla in 14.9% of cases. With a median follow up of 64.1 months (5.6-101.5) locoregional RFS and OS at 5 years were respectively 90% (IC95%: 88.1-92.4) and 90.9% (IC95%: 88.9-93). The 58.5% of patients developed grade 1 early skin toxicity, 35.9% grade 2, 4.5% grade 3. Concomitant CT with 5FU and Vinorelbine was associated with an increased grade 3 toxicity (P <0.001). In the long term, 29.8% of patients had telangiectasia (grade 1: 23.6%, grade 2: 5.2% Grade 3: 1%), which tended to be promoted by smoking (P = 0.056). 274 patients (34.4%) had breast reconstruction, on average 19.7 months after the end of radiation therapy (3.6 to 86.8 months). Twenty-four patients (3%) had early esophageal toxicity, not exceeding the grade 1. Of these patients, 21 had had chemotherapy and all were irradiated on the lymph nodes (including 23 on the IMC). Twenty-one patients developed heart disease after radiation therapy. Seventeen patients had received anthracycline and 9 trastuzumab. 3 patients developed ischemic heart disease, all irradiated on the left chest wall, IMC and supra and infraclavicular fossa, but all presented many cardiovascular risk factors (2 to 4). Our series have shown that the PMERT using our technique is effective and well tolerated.