Long term cancer outcomes from Study XXXX : A phase II study of accelerated partial breast irradiation with multicatheter brachytherapy following lumpectomy for early stage breast cancer
Mené sur 100 patientes atteintes d'un cancer du sein unifocal de stade I/II traité par lumpectomie en combinaison ou non avec une chimiothérapie adjuvante et/ou un traitement anti-hormonal (âge médian : 62 ans ; durée médiane de suivi : 12,1 ans), cet essai multicentrique de phase II évalue, du point de vue de la récidive ipsilatérale, des événements controlatéraux et de la survie à 10 ans, l'intérêt d'ajouter un traitement comportant une irradiation partielle accélérée du sein et une curiethérapie à plusieurs cathéters
Purpose : Accelerated partial breast irradiation (APBI) has increasingly gained acceptance in clinical practice despite relatively limited long term data. Study XXXX is a multi-institutional prospective trial that studied one of the earliest methods of APBI, multicatheter brachytherapy (MCT), and can uniquely provide long term cancer outcomes. Methods : Eligibility included stage I/II unifocal breast cancer < 3cm in size post lumpectomy with negative surgical margins and 0-3 positive axillary nodes without extracapsular extension. The APBI dose delivered was 34 Gy in 10 BID fractions over 5 days for High Dose Rate (HD); and 45 Gy in 3.5-5 days for Low Dose Rate (LDR) brachytherapy. The primary endpoint was HDR and LDR MCT reproducibility. This analysis focuses on long term ipsilateral breast recurrence (IBR), contralateral breast cancer events (CBE), regional recurrence (RR), and distant metastases (DM), disease-free (DFS), and overall survival (OS). Results : The median follow up is 12.1 years. 100 patients were accrued from 1997-2000; 98 were evaluable; 65 underwent HDR and 33 LDR MCT. Median age was 62; 88% had T1 tumors; 81% were p N0. 77% were estrogen (ER) and/or progesterone receptor (PR) positive; 33% received adjuvant chemotherapy and 64% antiendocrine therapy. There have been 4 isolated IBR and 1 IBR with RR, for 5.2% 10-year IBR without DM. There was 1 isolated RR, 1 with IBR, and 1 with a CBE, for 3.1% 10-year RR without DM. 10-year CBE was 4.2%, with 5 total events. Eleven patients have developed DM; 8 have died of breast cancer, and 22 have died from other causes. The 10-year DFS and OS are 69.8% and 78.0%, respectively. Conclusion : This multi-institutional Phase II trial studying MCT-APBI continues to report durable in breast cancer control rates with long term follow-up.