Purpose According to ASTRO and ESTRO guidelines, external beam Partial Breast Irradiation (PBI) is a valid option for early-stage Breast Cancer patients. Nevertheless, there is lack of consensus about the best treatment schedule.
METHODS We retrospectively analysed data of female patients treated at our institution from 2013 to 2022 with adjuvant “one-week" partial breast irradiation. Clinical Target Volume (CTV) was an isotropic expansion of 15 mm from the tumour bed (identified as the breast tissue between surgical clips). The treatment schedule was 30 Gy delivered with VMAT in 5 daily fractions. The primary endpoint was Local Control (LC). Disease Free Survival (DFS), Overall Survival (OS) and safety were secondary endpoints.
RESULTS Three hundred eighty-one patients with a median age of 69 (33 – 91) years were included in the study. One hundred ninety-two (50.4%) of the cases were left-sided breast; 360 (94.5%) were invasive ductal carcinomas, 368 (96.6%) were G1 or 2, and 378 (99.2%), were Luminal-like. After a median follow-up of 28 (6 – 104) months, 7 patients (2.0%) developed a local recurrence, of which two were “In field”. Three-year LC, DFS and OS actuarial rates were 97.5% (95% C.I. 96.2% – 98.8%), 95.7% (95% C.I. 94.2% - 97.2%), and 96.9% (95% C.I. 95.7% – 98.1%) respectively. No ≥ grade 3 acute/late toxicities were reported. 10 (2.9%) patients experienced grade 2 late toxicities. Five (1.5%) patients reported late cardiac major events, although 4 of them were treated on the right breast. Three (0.9%) late pulmonary toxicities were detected. One hundred-eight (30.8%) patients reported fat necrosis. Good or Excellent cosmetic evaluation following the Harvard Scale was reported in 252 (96.9%) cases by the physicians while in 241 (89.2%) cases by the patients.
CONCLUSION “One-week” PBI is effective and safe, and this schedule is a valid option for highly selected early breast cancer patients.