Ultra-hypofractionated 5-fraction radiation therapy for early breast cancer into whole breast and regional nodes: experience in a tertiary hospital

Post-surgery radiotherapy to the breast and regional lymph nodes decreases locoregional tumour recurrence and related mortality. The FAST-Forward approach, with 5 daily fractions, shows non-inferiority to the conventional 15-fraction scheme with similar safety. Authors suggest Simultaneous Integrated Boost (SIB) for the tumour bed and regional nodal irradiation (RNI) for comparable toxicity.

To describe acute and delayed toxicity in adjuvant radiotherapy patients using FAST-Forward scheme with SIB and analyze associations with patient characteristics.

An observational, descriptive, retrospective study on 120 early breast cancer patients (pT1-3, pN0-1, M0), treated with surgery and adjuvant radiotherapy using the FAST-Forward scheme with SIB at our center. Some also received RNI. Study conducted from June 2021 to October 2023.

Median age: 55 years (range 30–86). Main histological type: infiltrating ductal carcinoma (80%), with Luminal A as predominant molecular subtype (58.5%). Stage IA tumours (61%), pT1c (40%), G2 (50%). Treatment included: neoadjuvant chemotherapy (18.3%), adjuvant chemotherapy (23.5%), hormonal treatment (82.5%), surgery (99%). Radiotherapy with SIB in 90% of conservative surgeries with a median dose 30 Gy (range: 29–33.6). There was no significant association between acute/chronic toxicity and SIB found. However, there was increased risk of acute induration with neoadjuvant chemotherapy. Adjuvant chemotherapy was linked to significant rates of acute and delayed hyperpigmentation. The acute toxicity in first 6 months post-radiotherapy was only G1. The most frequent late toxicities were G1 indurations, edema, hyperpigmentation.

The FAST-Forward scheme with SIB and RNI in 5 daily fractions seems well-tolerated without severe acute or delayed toxicity.