Accelerated fractionation with a concurrent boost for early stage breast cancer.

Hypofractionated radiation refers to treatment with greater than 2 Gy per fraction, usually in fewer number and an overall shorter treatment period, compared to conventional radiation fractionation. Randomized prospective trials of hypofractionated whole breast irradiation (WBI) have demonstrated comparable outcomes as conventional fractionation in early stage postlumpectomy radiation in selected groups of patients. These data have changed the traditional radiobiology estimation of the alpha/beta ratio that predicted fractionation sensitivity for breast cancer, suggesting that further increase in dose per fraction is possible for early stage breast cancer without significantly increasing late effects. Many questions remain regarding hypofractionated WBI and span from optimal patient selection to radiation technique including dose planning optimization and the incorporation of a tumor bed boost. A concurrent radiation boost has been studied in a number of single institution studies and has shown to be feasible with acceptable acute and short-term late toxicity. A phase III trial by the Radiation Therapy Oncology Group (RTOG 1005) in North America and other trials in Europe are currently studying in-breast cancer control from hypofractionated WBI with a concurrent tumor bed boost. Results from these current trials could improve the acceptance and broaden the applicability of hypofractionation treatment courses for the treatment of patients with early stage breast cancer.