Long-Term Results of Intensity Modulated Radiotherapy (IMRT) with Helical Tomotherapy in Non-Metastatic Breast Cancer Patients: Final Analysis

<b>Background:</b> Intensity modulated radiotherapy with helical tomotherapy (IMRT-HT) is used in the breast cancer (BC) treatment for years now to obtain homogeneous dose distribution in the treated volumes and reduce the doses to organs at risk. The purpose of this study was to evaluate our experience in terms of local control, overall survival, progression free survival and adverse events in BC patients treated with IMRT-HT with long term follow-up. <b>Methods:</b> This study is a retrospective data analysis of patients irradiated with IMRT-HT. Overall survival (OS) and progression free survival (PFS) curves were plotted with Kaplan-Meier method. We also analyzed the OS and PFS data by molecular subgroups of the population. Long-term toxicities including skin, cardiac and pulmonary complications were also evaluated. Multivariant logistic regression analysis was performed to determine the independent predictors of the side effects. <b>Results:</b> Between 2009 and 2015, a total of 194 breasts in 179 women with nonmetastatic breast cancer were treated. Most of the tumors were grade III and N+. With a median follow-up of 10 years, we observed 9 local recurrences, 2 loco-regional recurrences, and 29 patients experienced metastatic disease. Only 18 patients are dear, of them 7 cases with breast cancer death. At 10 years, the Local recurrence free survival was 95.3% [95%CI: 92.1-98.5], the loco-regional relapse free survival was 94.5% [91.1-98.1]. The metastases free survival was 82.9% [76.9-89.3]. The progression free survival was 79.9 [73.6-86.7]. The cancer specific survival was 94.3%, and the overall survival 88% [82.8-93.5]. At long term, there were no cardiac, lung, thyroid, digestive radio induced toxicities. A small number of patients experienced grade I or II fibrosis. <b>Conclusions:</b> IMRT-HT could be safely used for adjuvant breast cancer irradiation in patients with complex anatomy. IMRT-HT provides favourable long-term prognosis, while late toxicity is acceptable.