Background Large-scale trials have shown that hypofractionated adjuvant breast radiotherapy was as effective in terms of survival and local control as conventional fractionated radiotherapy, and acute toxicity was reduced with hypofractionated radiotherapy. However, there is a lack of data about the toxicity of breast with regional nodal irradiation (RNI). The aim of this study was to assess the effect of fractionation on radiation-related acute skin toxicity in patients receiving RNI in addition to whole-breast or chest wall irradiation, using real-life data. Methods We conducted a prospective, multicenter cohort study with systematic computerized data collection integrated into Mosaiq®. Three comprehensive cancer centers used a standardized form to prospectively collect patient characteristics, treatment characteristics and toxicity. Results Between November 2016 and January 2022, 1727 patients were assessed; 1419 (82.2%) and 308 (17.8%) patients respectively received conventional fractionated and hypofractionated radiation therapy. Overall, the incidence of acute grade 2 or higher dermatitis was 28.4% (490 patients). Incidence was lower with hypofractionated than with conventional fractioned radiation therapy (odds ratio (OR) 0.34 [0.29;0.41]). Two prognostic factors were found to increase the risk of acute dermatitis, namely 3D (vs IMRT) and breast irradiation (vs chest wall). Conclusion Using real-life data from unselected patients with regional nodal irradiation, our findings confirm the decreased risk of dermatitis previously reported with hypofractionated radiation therapy in clinical trials. Expansion of systematic data collection systems to include additional centers as well as dosimetric data is warranted to further evaluate the short- and long-term effects of fractionation in real life.

IntroductionStereotactic radiotherapy may improve the prognosis of oligometastatic patients. In the literature, there is very little data available that is specific to breast cancer.Materials and MethodsWe conducted a multicenter retrospective study. The primary objective was to estimate progression-free survival after stereotactic body radiotherapy (SBRT) using Cyberknife of breast cancer oligometastases. The secondary objectives were to estimate overall survival, local control, and toxicity. The inclusion criteria were oligometastatic breast cancer with a maximum of five lesions distributed in one to three different organs, diagnosed on PET/CT and/or MRI, excluding brain metastases and oligoprogressions. This was combined with systemic medical treatment.FindingsForty-four patients were enrolled from 2007 to 2017, at three high-volume cancer centers. The patients mostly had one to two lesion(s) whose most widely represented site was bone (24 lesions or 44.4%), particularly in the spine, followed by liver (22 lesions or 40.7%), then pulmonary lesions (six lesions or 11.1%). The primary tumor expressed estrogen receptors in 33 patients (84.6%); the status was HER2+++ in 7 patients (17.9%). The median dose was 40 Gy (min-max: 15-54) prescribed at 80% isodose, the median number of sessions was three (min-max: 3-10). The median D50% was 42 Gy (min max 17-59). After a median follow-up of 3.4 years, progression-free survival (PFS) at one year, two years, and three years was 81% (95% CI: 66-90%), 58% (95% CI: 41-72%), and 45% (95% CI: 28-60%), respectively. The median PFS was 2.6 years (95% CI: 1.3 – 4.9). Overall survival at three years was 81% (95% CI: 63-90%). The local control rate at two and three years was 100%. Three patients (7.3%) experienced G2 acute toxicity, no grade ≥3 toxicity was reported.ConclusionThe PFS of oligometastatic breast cancer patients treated with SBRT appears long, with low toxicity. Local control is high. SBRT for oligometastases is rarely applied in breast cancer in light of the population in our study. Phase III studies are ongoing.

No abstract

No abstract