Targeted intraoperative radiotherapy tumor bed boost during breast conserving surgery after neoadjuvant chemotherapy in hormone receptor positive HER2 negative breast cancer.

e12090Background: Targeted intraoperative radiotherapy (TARGIT – IORT) as a tumor bed boost during breast conserving surgery is an established option for women with early breast cancer. In a previous study our group could show a beneficial effect of TARGIT-IORT on overall survival after neoadjuvant chemotherapy compared to an external boost in an unselected cohort. In this study we present an analysis of the hormone receptor positive HER2 negative subgroup. Methods: In this non-randomized cohort study involving 46 hormone receptor positive HER2 negative patients after NACT we compared outcomes of 21 patients who received a tumour bed boost with IORT (TARGIT-IORT) during lumpectomy versus 25 patients treated in the previous 13 months with external (EBRT) boost. All patients received whole breast radiotherapy. Disease free survival (DFS) and overall survival (OS) were compared. Results: There were no statistical differences between the two groups regarding tumor size, grading, nodal status and pCR rates. Me...