Feasibility and early toxicity of intraoperative radiotherapy for breast cancer using the papillon plus system: First results

Background and Purpose: Breast intra operative radiation therapy has been evaluated with different systems delivering 20-21 Gy with treatment times around 30 min. Papillon + (TM) Contact X-ray machine was designed to produce a 50 kVp beam with a high dose rate >= 15 Gy/minute. A pilot study with the first prototype was conducted in Nice. Materials and methods: The inclusion criteria were age >= 60 years, unifocal ductal breast adenocarcinoma <= 2.5 cm, grade 1-2. Surgical local excision with sentinel node dissection was performed and the applicator was placed in the tumor bed after excision with a prescribed dose of 20 Gy. The main end point of the study was the doses measured with the Gafchromic films; two were located at the skin surface and two in the excision cavity. Secondary endpoints were early toxicity and relapse free survival. Results: Between 10/2018 and 09/2019, 26 patients were included. Mean Gafchromic doses were 18.8 Gy +/- 2 Gy at the south pole, 15.6 Gy +/- 2.81 Gy at the equator and 2.5 Gy +/- 1.67 Gy at the skin. With a median follow-up time of 12 months, no skin or subcutaneous toxicity > grade 2, no local relapse and no metastasis were observed. C onclusion: This is the first phase II study testing the Papillon + tm system for breast IORT with in vivo dosimetry measurements and reassuring clinical data.