Accelerated Partial Breast Irradiation for Early-Stage Invasive Lobular Carcinoma
Menée à partir de données 2010-2022 portant sur 1 248 patientes atteintes d'un cancer du sein, cette étude analyse l'efficacité, du point de vue du taux de récivide locale et de la survie globale, d'une irradiation partielle accélérée chez les patientes présentant un carcinome lobulaire invasif
Purpose : Invasive lobular carcinoma (ILC) represents 10-15% of invasive breast cancers with limited representation among trials of accelerated partial breast irradiation (APBI). Contemporary guidelines advise against treating ILC with APBI given a paucity of supportive evidence. Here, we evaluated oncologic outcomes among patients with ILC treated with APBI.
Methods : Patients treated from 2010 –2022 with APBI following breast conserving surgery for ILC (or mixed ILC with other histologies) were ascertained from a prospectively-maintained institutional database. All patients received external beam APBI to 40Gy in 10 daily fractions. Outcomes of interest included local recurrence (LR) and overall survival (OS).
Results : Of 1248 patients who underwent APBI at our center, the study cohort comprised 132 (11%) who had ILC, either exclusively or mixed with another histology (median age 63). Median tumor size was 1.1cm (IQR: 0.8, 1.5), nearly all had estrogen receptor positive disease (99%) and received endocrine therapy (91%), and most underwent sentinel node biopsy (89%) with the remainder having no axillary surgery. At 530 person-years and a median follow-up of 39 months, two LRs were observed yielding a 48-month cumulative incidence of LR of 3.0% (95% CI 0.56 –9.5%). Both events arose in patients with mixed lobular histology (none arose in patients with pure ILC). Two unrelated deaths were also observed yielding a 48-month overall survival of 98% (95% CI: 95% - 100%)
Conclusion : Among patients with ILC who received APBI following BCS, we observed a 4-year LR rate of 3%. No regional or distant recurrences were observed, and overall survival was excellent. The safety of APBI for ILC will require confirmation among larger trials with longer follow-up, although the excellent outcomes observed here are consistent with those seen for invasive ductal carcinomas among contemporary trials of APBI.
International Journal of Radiation Oncology,Biology,Physics , résumé, 2024