Longitudinal cosmetic outcome after planned IORT boost with low kV X-rays-monocentric results from the TARGIT BQR registry.

Background: Intraoperative radiotherapy can serve as an anticipated boost (IORT boost) in combination with a subsequent external whole breast irradiation in high-risk breast cancer patients and is part of many guidelines. Nevertheless, there are only few prospective data available regarding cosmetic outcome after IORT boost using kV X-rays. The aim of this study was to evaluate the cosmetic outcome of patients treated within the prospective phase IV TARGeted Intraoperative radioTherapy (TARGIT) Boost Quality Registry (BQR) study (NCT01440010) in one center. Methods: In the context of the TARGIT BQR study standardized photos in three positions (arms down, arms up, from the side) were available for different time points. For this analysis a layperson, a radiation oncologist and a gynecologist evaluated available photos at different time points during follow-up with up to 4 years using the Harvard scale (comparison of treated and the untreated breast; rating: excellent, good, fair, poor). Longitudinal results were compared to preoperative results (baseline). Results: Seventy-three patients were available for the analysis. Baseline cosmetic assessment was excellent/good in 98.8% (mean value for all three positions). Postoperative cosmetic outcome (median) was good for all positions and remained constant for 4 years. Around 30% of the patients showed a constant or even improved cosmetic outcome compared to baseline. Only few patients showed a poor result at 4 years. The majority of patients showed an excellent or good cosmetic outcome at all time points. Conclusions: Patients from the prospective TARGIT BQR study treated with IORT boost and additional whole breast irradiation showed good or excellent cosmetic outcomes in most cases during 4 years of follow-up. These results add important information for shared decision making in breast cancer patients.