Standard Radiotherapy Fractionation Toxicity Versus Ultra-Hypofractionation In Breast Cancer

ABSTRACT

Purpose or Objective Radiotherapy is an essential treatment in the local control of breast cancer. Standard treatment is currently carried out in 15 daily sessions. At present, following the results of the phase III Fast-Foward trial and in view of the situation triggered by COVID-19, the number of sessions has been reduced to 5. The RHEMA (extreme hypofractionated radiotherapy in breast cancer) study has been initiated in Spain. It is a multi-hospital study designed to determine the evolution of the change in fractionation. The hypothesis is that the change in fractionation does not increase acute toxicity. The aim of the study was to determine whether there are differences in acute skin toxicity in breast cancer patients who receive adjuvant radiotherapy according to the different fractionation schedules applied. Materials and Methods We retrospectively analysed skin toxicity in patients treated with glandular radiotherapy at the end of treatment and one month later. Out of 75 patients treated with the ultra-hypofractionated schedule, 58 patients with a follow-up of more than 1 month were compared with 38 patients who received the standard schedule, all of whom were treated in 2020 in the Multihospital Clinical Unit of Radiation Oncology of Aragon. In the case of the ultra-hypofractionated treatment, as indicated in the GEORM (Spanish group of breast radiation oncology) guidelines at the beginning of the pandemic, was carried out in 5 sessions with a total dose of 26 Gy over the breast and 29 Gy over the tumour bed, while the standard treatment, consisted in 15 sessions with a total dose of 40.5 Gy over the breast and 48 Gy over the tumour bed. Results The median age was 61 years in the standard group and 63.4 years in the ultra-hypofractionated group. No significant differences were observed in the histological profile. Differences were found in toxicity at the end of treatment, being significantly higher in the standard group (p 0.03). On the other hand, no differences were found in toxicity one month after the end of treatment. Grade 2 toxicity appeared in 2 patients from the ultra-hypofractionated group and 4 from the standard group, with no significant difference (p 0.943). There were no differences in the development of grade 1 toxicity and no grade 3 or higher toxicity was observed. Conclusion It can be concluded that the use of the ultra-hypofractionation schedule compared to standard treatment was not associated with an increase in acute skin toxicity in our series. This is a change in fractionation that could be adopted as a routine treatment in radiation oncology departments after verifying the results with a larger number of patients and a longer follow-up.