Outcome of a phase II prospective study on partial breast irradiation with interstitial multi-catheter high-dose-rate brachytherapy

Abstract

Background and purposePartial breast irradiation (PBI) is an alternative to whole-breast irradiation after breast-conserving surgery in selected patients. Until the results of randomized phase III studies are available, phase II studies inform about PBI. We report the 5year results of a phase II prospective study with PBI using interstitial multi-catheter high-dose-rate brachytherapy (ClinicalTrials.gov Identifier: NCT00499057). MethodsHundred patients received PBI (4Gy, twice a day for 4days, until 32Gy). Inclusion criteria were: age ⩾40years, infiltrating carcinoma without lobular histology, ductal in situ carcinoma, tumor size ⩽2.5cm, negative surgical margins and axillary lymph nodes. ResultsAt a median follow-up of 60months late toxicity occurred in 25 patients; the 5-year probability of freedom from late toxicity was 72.6% (95% CI: 63.7–81.7). Tamoxifen was the only significant risk factor for late toxicity. Cosmetic results, judged by physicians and patients, were good/excellent in 98 patients. Three local relapses (1 true, 2 elsewhere) and 1 regional relapse occurred. The 5-year probability of local or regional relapse-free survival was 97.7% (95% CI: 91.1–99.4) and 99.0% (95% CI: 92.9–99.8), respectively. ConclusionPBI with interstitial multi-catheter brachytherapy is associated with low relapse and late toxicity rates.