Background: Conventional fractionated radiation therapy over 4-5 weeks with sequential boost is the standard of care for postoperative RT treatment for patients with early stage breast cancer who undergo BCS. However, the use of an accelerated RT course can be used in departments with high patients flow to reduce waiting list and machine loads as well as to improve patient compliance.

Patients and Methods: This is a prospective phase II study conducted at Kasr El-aini Center of Clinical Oncology and Nuclear Medicine (NEMROCK). Patients who underwent breast conservative surgery were recruited according to inclusion and exclusion criteria. Recruited patients were planned using 3D conformal technique to receive a hypofractionated radiation schedule using 40 Gy/2.67 Gy per fraction over 3 weeks to the whole breast with Concurrent boost 8.0 Gy/0.5 Gy per fraction over 3 weeks. Dosimetric parameters for the coverage of the breast CTV were set using V38, V36 Gy and the homogeneity using the Dmax and the Dmin. For the coverage of the boost PTV V45.6Gy and V43Gy were used and for dose homogeneity Dmax and Dmin. As regard dose constrain for organ at risk (OAR), no more than 20% of the ipsilateral lung exceeds 16 Gy, no more than 5% of the whole heart exceeds 20 Gy. All patients was evaluated for acute toxicity and cosmetic outcome.

Results: During the period from June 2014 to January 2017, a total of 63 patients with a median age of 51 years were included. The dosimetric parameters for the coverage of target volumes and dose constrain for OAR were in compliance with our protocol. Regarding acute skin toxicity, only 20% of patients developed GII skin toxicity, while 68% of patients developed G0-I skin toxicity, none of the patients developed GIII or more skin toxicity. The overall cosmetic assessment was excellent in 80.95 % of patients and good in 19% of patients.

Conclusions: Hypofractionated radiotherapy in three weeks to the whole
breast with a concomitant boost in patients undergoing breast conserving surgery (BCS), allows acceptable outcomes in terms of dosimetric parameters, acute toxicity and early cosmetic results and is a good approach for our department NEMROK due to the reduction of 15 days when compared to standard RT treatment of breast cancer. long- term follow up data are needed to assess late toxicity, cosmesis, and clinical outcomes.