Early-stage Breast Cancer: Tailored External Beam Fractionation Approaches for Treatment of the Whole or Partial Breast.

Abstract

Historically, radiotherapy fractionation for early-stage breast cancer primarily consisted of 1.8-2 Gy per fraction given once daily to a total dose of 45-66 Gy over 5-7 weeks for whole breast treatment. Partial breast treatment employed larger dose per fraction (3.4-3.85 Gy) in 10 fractions given twice daily over 1 week. Radiobiologically, breast cancer is increasingly appreciated as a low alpha-beta ratio malignancy that is best treated with larger dose per fraction. Over the past 10 years, there have been increasing data from multiple large randomized clinical trials that support the use of shorter treatment courses: first hypofractionated regimens consisting of 15-20 treatments, and more recently, ultra-hypofractionated regimens as short as 5 treatments. Simultaneously, data from modern partial breast irradiation (PBI) trials support once daily treatment regimens ranging from 1-5 treatments. Shorter treatment courses represent less treatment burden on patients, reduced financial impact, and potentially improved access to care for patients with transportation and/or socioeconomic barriers. Here we review the evolution of whole and partial breast treatment regimens for early-stage breast cancer.