Intraoperative radiotherapy (IORT) as a boost in patients with early-stage breast cancer -- acute toxicity.

BACKGROUND: We report on acute toxicities as well as the early cosmetic outcome of patients receiving intraoperative radiotherapy (IORT) followed by whole-breast radiotherapy (WBRT) compared to patients treated with standard WBRT alone.

PATIENTS AND METHODS: From 2/2002 until 2/2005, 84 breast cancer patients were treated with IORT during breast-conserving surgery (BCS) as a boost (20 Gy/50 kV X-rays) followed by WBRT. After wound healing, all IORT patients were treated with WBRT at a total dose of 46 Gy. For the purpose of comparison, 53 patients treated consecutively between 1/2003 and 12/2004 in our institution with BCS followed by WBRT at a total dose of 50-66 Gy, were analyzed. All patients had a defined followup schedule. Toxicities were prospectively documented using the CTC/EORTC Score. Cosmesis was evaluated after 6 months using a 1-4 score.

RESULTS: Treatment was well tolerated with no grade 3/4 acute toxicity. Rare adverse effects following IORT included wound healing problems (2%), erythema grade I-II (3%), palpable seroma (6%) and mastitis (2-4%). The number of patients with induration of the tumor bed was comparably low.

CONCLUSION: IORT with the IntrabeamTM system applied as a boost during BCS, followed by 46 Gy WBRT, exerts similar acute toxicity as standard WBRT. Further follow-up is needed to assess long-term toxicity and efficacy.