Incidence of local recurrence in patients after breast-conserving surgery and postoperative radiotherapy with or without a supplementary radiation.

159 Background: We evaluated the incidence of local recurrence (LR) among patients (pts) who received radiotherapy with/without a supplementary dose of radiation (boost) to the tumor bed after breast-conserving surgery (BCS) for early breast cancer (BC). Methods: In our retrospective analysis (from 2000-2004) 449 pts with stage I/II BC received 50Gy of radiation to the whole breast in 2Gy fractions over a five-week period after BCS. There were 328 pts (73%) with microscopically complete excision (>5mm margins) and 121 pts (27%) with a microscopically incomplete excision (≤5mm margins). Patients with a microscopically complete or incomplete excision were randomly assigned to receive either no further local treatment (190) or an additional localized dose (309) of 10-16Gy, usually given in 5-8 fractions (fr) by electrons/15Gy in 3 fr by HDR interstitial brachytherapy. Results: During a median follow-up period of 79 months (min 20, max 120), the cumulative incidence of LR was 3% for all group of pts (449). Th...