This is a prospective non randomized phase two trial evaluating the feasibility of a ten fraction accelerated hypofractionated radiotherapy schedule with simultaneous integrated boost risk adapted in patients undergoing breast conserving surgery for early breast cancer

Patients enrolled for the study, according to eligibility criteria, undergo breast conserving surgery followed by adjuvant 10-fraction whole breast irradiation with a risk adapted simultaneous-integrated boost dose at the level of the tumour bed according to clinical and pathological risk factors.

Inclusion Criteria:

• Histologically proven invasive or in situ unifocal adenocarcinoma of the breast
• Breast conserving surgery
• Pathological pTis G3, pT1-2 any Grade, pN0 or pN0(sn) (isolated tumor cells [i+] allowed) pN1mic, M0 stage
• Postoperative negative (no ink) final surgical margins
• Patient requires a whole breast radiotherapy plus a tumor bed boost
• Female patients aged ≥ 18 years of any menopausal status
• ECOG performance status 0-2

Exclusion Criteria:

• Past history of malignancy except basal cell skin cancer and CIN cervix uteri or non-breast malignancy allowed if treated with curative intent and at least 5 years' disease free
• Mastectomy
• Concomitant chemotherapy (primary or sequential chemotherapy allowed) (Chemotherapy and radiotherapy must be separated by a minimum of 2 weeks). (Patients receiving neo-adjuvant chemotherapy are not excluded)
• Known disorders associated with a higher risk for complications following radiotherapy such as collagen vascular disease, dermatomyositis, systemic lupus erythematosus or scleroderma
• Any psychological, familiar, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule
• Any serious uncontrolled medical disorder, non-malignant systemic disease, or active uncontrolled infection. Example include but are not limited to uncontrolled ventricular arrhythmia, recent (within 3 months) myocardial infarction or uncontrolled major seizure disorder
• Pregnant or lactating patients
• Presence of ipsilateral breast implant
• Prior breast or thoracic radiotherapy for any condition