Skin toxicity is the most common side-effect of radiotherapy for breast cancer. This study aimed to investigate whether inverse-planned intensity-modulated radiotherapy (IMRT) would reduce skin toxicity incidence compared with forwarding field-in-field breast IMRT early-stage breast cancer. This phase 3 randomized controlled trial was aimed to compare breast irradiation with either FiF-IMRT or helical tomotherapy IMRT, with skin toxicity as the primary endpoint. In total, 177 patients were available for assessment, and the median follow-up was 73 months. There were no differences between the treatment arms in case of late toxicities.

The five year non recurring survival rate was 96% for both FiF-IMRT and HT-IMRT, and the overall survival was 97.4% and  96.3%for FiF-IMRT and HT-IMRT, respectively. The study showed a significant reduction in acute skin toxicity using HT-IMRT compared with FiF-IMRT, without significantly reducing late skin toxicities. Based on these findings, inversely planned IMRT could be used in clinical practice for complete breast irradiation with planning and optimization to achieve the required dosage constraints for organs at risk; not translating into skin fibrosis.

In conclusion, cute skin toxicity is correlated with large breast volume, adjuvant chemotherapy, and radiotherapy technique. Carefully planned optimization is required to generate inverse IMRT plans without exceeding dose limits for OARs.