Whole breast irradiation (WBI) vs. Intraoperative Electron Radiotherapy (IOERT) for Breast Conserving Therapy: A large mature single institution matched-pair evaluation of true local relapse, progression free survival and overall survival
Menée à partir de données monocentriques 2000-2010 portant sur 516 patientes atteintes d'un cancer du sein (durée médiane de suivi : 154-157 mois), cette étude compare la survie et la récidive après une radiothérapie peropératoire et après une irradiation du sein entier
Background and purpose: Comparative outcome data after intraoperative radiotherapy (IORT) and whole breast irradiation (WBI) for breast cancer at >10ys median follow-up are rare. We present a mature single-institution matched-pair comparison reporting survival and relapse rates in patients treated with either modality. Materials and methods: Complete datasets for 258 IOERT patients treated between 2000 and 2010 were matched with 258 patients postoperatively treated with WBI by age/histology/tumor size, grading/lymph-node-status/hormone receptors/type of adjuvant therapy/surgical margins and treatment date. Relapse at surgical intervention site was classified as true local recurrence (LR). All recurrences in the treated breast (any quadrant) were classified as Ipsilateral Recurrence (IR). Results: Median follow-up was 157 months (12-251) for the IOERT group, 154 months (31-246) for the WBI group. Cumulative incidence of IR at 5, 10 and 15 years was 2.4%, 7.9% and 12.7% for IOERT and 1.2%, 4.1% and 5.0% for WBI (p=0.02). Cumulative incidence of LR at 5, 10 and 15 years was 1.6%, 5.1% and 8.3% for IOERT and 0.4%, 2.1% and 2.5% for WBI (p=0.02). No differences in overall survival, disease free survival, second-cancer-incidence and cardiac events were recorded in both treatment groups. Outcome was better in the APBI-suitable group than in the APBI-unsuitable group (2009 criteria) (cumulative incidence of IR at 5, 10 and 15 years was 0% vs 7.3%, 6.1% vs 13.3% and 7.3% vs 19.9% for IOERT and 0% vs 1.8%, 2.0% vs 3.9% and 3.1% vs 3.9% for WBI) and in the revised APBI-suitable group than in the APBI-cautionary group (2017 criteria) (cumulative incidence of IR at 5, 10 and 15 years was 1.1% vs 6.4%, 6.2% vs 13.3% and 7.8% vs 27.5% for IOERT and 1.7% vs 0%, 4.1% vs 4.4% and 5.4% vs 4.4% for WBI). Conclusion: IR and LR rate were higher after IOERT than after WBI also for the “ASTRO-suitable” patient group, although without reaching statistical significance. Thus, IOERT could be an alternative to WBI upon stringent patient selection but patients should be counseled carefully about the potential for increased IR-rate with IOERT. Second-cancer-incidence and cardiac events did not differ between IOERT and WBI.
International Journal of Radiation Oncology, Biology, Physics