Intraoperative radiotherapy vs. multicatheter brachytherapy as accelerated partial-breast irradiation: a secondary analysis of two multicenter prospective cohorts.

AIM: The aim of this study is to compare for the first time the IBTR rates observed among early breast cancer patients treated either by multi-catheter brachytherapy or IORT in two prospective multicenter cohorts. Secondary objectives included, regional and distant relapse rates, mastectomy-, disease-, and cause-specific free survival, and overall survival.

MATERIALS AND

METHODS

Two multicenter prospective studies of partial-breast irradiation were ongoing at the University Hospitals of Las Palmas province. A province-wide prospective cohort was established to evaluate interstitial brachytherapy in patients undergoing breast-conserving treatment. This cohort comprised 182 women treated between 2008 and 2017 across all university-affiliated hospitals in Las Palmas. A second prospective multicenter investigation assessed the use of intraoperative radiotherapy (IORT) as exclusive partial-breast irradiation. This study included 312 patients treated between January 2013 and December 2022 by three surgical teams operating at the academic university hospitals of the Las Palmas province.

RESULTS

Two out of the 182 patients of the Brachytherapy cohort developed a local recurrence (LR) during the first 5 years of follow-up. The actuarial IBTR risk at 5 years was 1.1% (95% CI: 0.3-1.9). During the follow-up, three out of the 312 patients of the IORT cohort developed a local recurrence (LR). The actuarial IBTR risk at 5 years was 1.0% (95% CI 0.4-1.6). These differences were not statistically significant (p=0.885).

CONCLUSION

In our opinion, this secondary analysis of two prospective multicenter cohorts may offer new information regarding the role of interventional APBI in early breast cancer patients, stratified by the GEC-ESTRO risk groups.