Cosmetic Outcome and Late Breast Toxicity After Intraoperative Radiation Therapy as a Single Modality or as a Boost Using the Intrabeam® Device: A Prospective Study

Abstract

We aim to report our results in terms of late toxicities and cosmetic outcomes after intraoperative radiotherapy (IORT) using kV X-rays in women treated for early breast cancer at our institution. Patients were eligible if they met the following criteria: age ≥50, non-metastatic grade 1-2, Erb2 negative hormone receptor positive unicentric-unifocal and ≤ 3 cm non-lobular early breast carcinoma. Patients were treated with IORT using the kV X-rays Intrabeam® device following lumpectomy and sentinel node biospy. IORT was completed by whole breast radiotherapy (WBRT) at the dose of 46 in 23 fractions to 50.4 Gy in 28 fractions (depending on breast size) in case of adverse pathologic criteria on the final specimen examination. Breast toxicity was graded using the LENT SOMA scale every 6 months and cosmetic outcomes were evaluated at 36 months by patient self-evaluation and by 2 radiation oncologists on a 1-10 scale. Between April 2011 and November 2014, 71 patients were included. Forty-one women received IORT only and 30 patients received IORT followed by WBRT. After a median follow up of 38.9 months, no locoregional or distant recurrence occurred. After IORT only, 2.4% of grade ≥2 breast fibrosis, 41.5% of grade 1 breast retraction, and 7.3% of grade 1 breast edema was observed. No patient developed another grade ≥2 toxicity. In the IORT +WBRT group, grade ≥2 fibrosis, grade ≥2 breast retraction, and grade 1 breast edema were 43.3%, 23.3% and 16.7%, respectively. There was a significant difference in terms of skin grade ≥2 toxicity between IORT only and IORT +WBRT (2.4% versus 46.6%) (p=0,0001). Objective cosmetic outcomes were very good and significantly better in the IORT only group compared to the IORT+ WBRT group (8.87 vs 6.96) (p<0.001). IORT using the Intrabeam® is well tolerated with very little late skin and breast toxicity and very good cosmetic outcome. However, a high rate of grade ≥2 late skin toxicity was observed when IORT had to be completed by WBRT.