Volumetric modulated arc therapy (VMAT) to deliver nodal irradiation in breast cancer patients.

To evaluate feasibility, safety, toxicity profile and dosimetric results of volumetric modulated arc therapy (VMAT) to deliver regional nodal irradiation (RNI) after either mastectomy or breast conservation (BCS) in high-risk breast cancer patients. Between January 2015 and January 2017, a total of 45 patients were treated with VMAT to deliver RNI together with whole breast or post-mastectomy radiotherapy. The fractionation schedule comprised 50 Gy in 25 fractions given to supraclavicular and axillary apex nodes and to whole breast (after BCS) or chest wall (after mastectomy). Two opposite 50°-60° width arcs were employed for breast ad chest wall irradiation, while a single VMAT arc was used for nodal treatment. Treatment was generally well tolerated. Acute skin toxicity was G2 in 13.3% of patients. Late skin toxicity consisted of G1 induration/fibrosis in six patients (13.3%) and G2 in 1 (2.2%). Dosimetric results were consistent in terms of both target coverage and normal tissue sparing. In conclusion, VMAT proved to be a feasible, safe and effective strategy to deliver RNI in breast cancer patients after either BCS or mastectomy with promising dosimetric results and a mild toxicity profile.