A Japanese prospective multi-institutional feasibility study on accelerated partial breast irradiation using multicatheter interstitial brachytherapy: clinical results with a median follow-up of 60 months

We carried out the first multi-institutional prospective study on accelerated partial breast irradiation (APBI) via multicatheter interstitial brachytherapy in a shorter period for early breast cancer in Japan.Patient eligibility criteria included positive hormone receptors, tumors ≤ 3 cm and TNM stage pN0M0. After breast-conserving surgery (Japanese cylindrical resection) and histological confirmation of negative surgical margins and the absence of lymph node metastasis, applicator implantation was performed either postoperatively or intraoperatively. High-dose-rate brachytherapy of 36 Gy in 6 fractions was delivered.Forty-six patients from six institutions received this treatment regimen, and the median follow-up time was 60 months (range 57-67 months). The median resected breast tissue volume was 81 cmThis study showed excellent local control and survival results with minimal late sequelae.