Ultrahypofractionation in postoperative radiotherapy for breast cancer: A single‐institution retrospective cohort series

Abstract

Abstract Background The ‘FAST‐forward’, study published in April 2020, demonstrated the effectiveness of an extremely hypofractionated radiotherapy schedule, delivering the total radiation dose in five sessions over the course of 1 week. We share our department's experience regarding patients treated with this regimen in real‐world clinical settings, detailing outcomes related to short‐term toxicity and efficacy. Methods A descriptive observational study was conducted on 160 patients diagnosed with breast cancer. Between July 2020 and December 2021, patients underwent conservative surgery followed by a regimen of 26 Gy administered in five daily fractions. Results The median age was 64 years (range: 43–83), with 82 patients (51.3%) treated for left‐sided breast cancer, 77 patients (48.1%) for right‐sided breast cancer, and 1 instance (0.6%) of bilateral breast cancer. Of these, 66 patients had pT1c (41.3%), 70.6% were infiltrative ductal carcinomas, and 11.3% were ductal carcinoma in situ. Most tumours exhibited intermediate grade (41.9%), were hormone receptor positive (81.3%), had low Ki‐67 (Ki‐67 < 20%; 51.9%) and were Her 2 negative (85%). The majority of surgical margins were negative (99.4%). Among the patients, 72.5% received hormonotherapy, and 23.8% received chemotherapy. Additionally, 26 patients (16.3%) received an additional tumour boost following whole breast irradiation (WHBI) of 10 Gy administered in five sessions of 2 Gy over a week. The median planning target volume (PTV) was 899 cm3 (range: 110–2509 cm3). Early toxicity was primarily grade I radiodermatitis, affecting 117 patients (73.1%). During a median follow‐up of 15 months (range: 3.9–28.77), only one patient experienced a local relapse, which required mastectomy. Conclusions The implementation of this highly hypofractionated regimen in early‐stage breast cancer appears feasible and demonstrates minimal early toxicity. However, a more extended follow‐up duration would be required to evaluate long‐term toxicity and efficacy accurately.

Keywords

• breast cancer
• clinical observations
• radiation therapy
• radiotherapy