A Novel Form of Breast Intraoperative Radiation Therapy with CT-Guided High-Dose-Rate Brachytherapy : Results of a prospective phase I clinical trial
Mené sur 28 patientes atteintes d'un cancer du sein sans envahissement ganglionnaire (âge : supérieur ou égal à 50 ans ; durée de suivi : 6 mois), cet essai de phase I évalue la faisabilité et la sécurité d'une nouvelle méthode de radiothérapie intra-opératoire en combinaison avec une curiethérapie à haut débit de dose guidée par tomodensitométrie
Purpose : Existing intraoperative radiation therapy (IORT) techniques are criticized for the lack of image-guided treatment planning and energy deposition with, at times, poor resultant dosimetry and low radiation dose. We pioneered a novel method of IORT that incorporates customized, CT-based treatment planning and high-dose-rate (HDR) brachytherapy to overcome these drawbacks: CT-HDR-IORT. Methods : A phase I study was conducted to demonstrate the feasibility and safety of CT-HDR-IORT. Eligibility criteria included: age ≥ 50 years, invasive or in situ breast cancer, tumor size < 3 cm, and N0 disease. Patients were eligible before or within 30 days of breast conserving surgery (BCS). BCS was performed and a multi-lumen balloon catheter placed. CT images were obtained, a customized HDR brachytherapy plan created and a dose of 12.5 Gy delivered to 1 cm depth from balloon surface. The catheter was removed and the skin closed. Primary endpoints were feasibility and acute toxicity. Feasibility was defined as IORT treatment interval (time from CT acquisition until IORT completion) ≤ 90 minutes. Secondary endpoints included dosimetry, cosmetic outcome, quality of life and late toxicity. Results : 28 patients were enrolled. Six month follow-up assessments were completed by 93% of enrollees. Median IORT treatment interval was 67.2 minutes (range 50-108 minutes). The treatment met feasibility criteria in 26 women (93%). Dosimetric goals were met in 22 patients (79%). There were no RTOG grade 3+ toxicities; 6 patients (21%) experienced grade 2 events. Most patients (93%) had good/excellent cosmetic outcomes at last follow-up. Conclusions : CT-HDR-IORT is feasible and safe. This promising approach for a conformal, image-based, higher-dose breast IORT is being evaluated in a Phase II trial.