[Accelerated partial breast irradiation with three-dimensional conformal external beam radiotherapy following breast-conserving surgery -- preliminary results of a phase II clinical study].

The aim of the study was to implement accelerated partial breast irradiation (APBI) by means of three-dimensional conformal radiotherapy (3D-CRT) following breast-conserving surgery (BCS) for early-stage breast cancer. Between December 2006 and February 2011, in 45 cases of low-risk, stage I-II breast cancer the tumour bed was marked with titanium clips during BCS. Postoperative APBI was given by means of 3D-CRT using 3 to 5 non-coplanar fields. The total dose of APBI was 36.9 Gy (9 x 4.1 Gy) using a twice-a-day fractionation over 5 consecutive days. Early and late radiation side effects and cosmetic results were analysed for the first 30 patients with a minimum follow-up of 1 year. At a mean follow-up of 25.2 months neither loco-regional nor distant failure was observed. Excellent, good, fair, and poor cosmetic outcome was detected in 10 (33.3%), 16 (53.4%), 4 (13.3%), and 0 (0%) patients, respectively. Grade 2 or worse acute side effect was not observed. Grade 1 fibrosis, grade 2 teleangiectasia and asymptomatic fat necrosis occurred in 4 (13.3%), 1 (3.3%) and 5 (16.7%) patients, respectively. No grade 3-4 late side effects were detected. 3D-CRT is a reproducible and feasible technique for the delivery of APBI following conservative surgery for the treatment of low-risk, early-stage invasive breast carcinoma. The preliminary results are promising, early- and mid-term radiation side effects are rare, and cosmetic results are excellent.