Feasibility and safety of the "One-Week Breast Radiation Therapy" program

Introduction FAST-Forward and UK-FAST-trials have demonstrated the safety and efficacy of five-fraction breast adjuvant radiation therapy (RT) and have become the standard of care for selected early breast cancer patients. In response to the additional burden caused by the COVID-19 pandemic, we implemented "One-Week Breast RT", an innovative program delivering five-fraction whole breast RT, in a complete 5-day workflow. The primary objective of this study was to demonstrate the feasibility and safety of our program. The secondary objective was to evaluate cosmetic results. Material and methods A total of 120 patients treated from February 2021 to March 2022, received whole breast RT, without lymph node irradiation nor boost, with 26 Gy in five fractions over one week. Inverse planning with restricted optimization parameters offering systematic deep inspiration breath-hold aimed to provide treatment plans compliant with FAST-Forward recommendations. Toxicity and cosmetic evaluations were prospectively registered prior (pre-RT), at the end (end-RT), and 6 months after RT (6 month) based on CTCAE v4.03 and Harvard scale. Results With a median age of 70 years (interquartile range (IQR): 66-74) and a median follow-up of 6 months (IQR: 6.01-6.25) most patients (93.3%) completed their RT in one week from baseline to end of treatment consultation. The most common acute toxicities (at end-RT) were skin-related: radio-dermatitis (72%), induration (35%), hyperpigmentation (8%) and breast edema (16%) The rate of radio-dermatitis decreased from end-RT to-6 month (71.7% vs 5.4%, P< 0.001). No patient experienced grade ≥3 toxicity. At 6 months, cosmetic results were generally good or excellent (94.1%). Conclusion This study confirms the feasibility and acute safety of the "One-Week Breast RT" in real-life. Favorable toxicity profiles and good cosmetic outcomes are in line with FAST-Forward results. A prospective national cohort, aimed at decreasing treatment burden, maintaining safety, efficacy, and improving RT workflow efficiency with longer follow-up is ongoing.