Hypofractionated Whole Breast Radiotherapy with Simultaneous Integrated Boost Following Breast Conservative Surgery for Early Breast Cancer

Background: Hypofractionated whole breast radiotherapy (HFWBRT) showed comparable efficacy and safety to conventional fractionated radiotherapy. Dose and fractionation of the tumor bed boost to be integrated during HF-WBRT schedules is still to be determined. Aim: to investigate the clinical feasibility of HF-WBRT with simultaneous integrated boost (SIB), in early breast cancer patients who underwent breast conserving surgery (BCS). Methods: This single arm prospective study included 40 female patients with pathologically proven stage I-II breast cancer following BCS with high risk factors. Patients received 3D conformal radiotherapy (3DCRT) with field in field (FIF) technique. The whole breast received a dose of 40 gray (Gy) over 15 fractions for 3 weeks with an additional SIB dose of 8 Gy over 15 fractions to be give daily during WBRT. Radiation toxicities were graded using the common terminology criteria for adverse events (NCI-CTCAE) scale version 4.03. Cosmetic outcome was assessed using Harvard cosmetic score. Kaplan Meier method was used to estimate the 3- year disease free (DFS) and overall survival (OS). Results: The median age at presentation was 48 years (range 33-68). No reported grade 3 or 4 toxicities. Grade 1 and 2 radiation dermatitis affected 80% of the patients, breast pain was observed in 62.5% of the patients while 25% had radiation pneumonitis. Most of the patients (95%) had excellent and good cosmetic outcomes. At 3 years the estimated DFS was 95% and OS was 97.5 %. Conclusion: WBRT-SIB using 3DCRT with FIF technique is clinically feasible for early stage breast cancer patients.