This record contains raw data related to article "Hypofractionated volumetric modulated arc therapy in ductal carcinoma in situ Toxicity and cosmetic outcome from a prospective series" O BJECTIVE: Hypofractionated radiotherapy in early stage breast cancer is an effective adjuvant treatment, but there is a lack of randomized data for patients with ductal carcinoma in situ (DCIS). The aim of this study is the evaluation of skin toxicity and cosmesis, and early clinical outcome of DCIS patients enrolled in an institutional Phase II trial of hypofractionated breast irradiation. METHODS: 137 DCIS patients were enrolled in the trial. All patients underwent volumetric modulated arc therapy (VMAT) to the whole breast with a total dose of 40.5 Gy in 15 fractions over 3 weeks, without tumour bed boost. Acute and late skin toxicities were recorded. Cosmetic outcomes were assessed as excellent/good or fair/poor. Early clinical outcome was reported. RESULTS: Median age was 58 y.o. (range 30-86). The median follow-up time was 22 months (range 6-45). At the end of the radiotherapy, skin toxicity was grade G1 in 56% of the patients, G2 in 15%, no patients presented G3 toxicity. In the range of 3-9 months of follow-up, the skin toxicity was G1 in 28% of patients, no G2-G3 cases; cosmetic outcome was good/excellent in 95% of patients. In the follow-up interval of 9-24 months, the skin toxicity was G1 in 12% of patients, no G2-G3 toxicity; cosmetic outcome was good/excellent in 96% of patients. After an early evaluation of clinical outcomes, 5 patients (3.6%) presented an in-breast recurrence. CONCLUSION: Hypofractionated radiotherapy using VMAT is a viable option for DCIS. A longer follow-up is needed to assess clinical outcomes and late toxicity. Advances in knowledge: The use of hypofractionated VMAT is dosimetrically feasible for treating breast DCIS.