Preliminary report on ultrashort perioperative partial-breast irradiation with multicatheter interstitial brachytherapy for early-stage breast cancer

Abstract

Abstract PURPOSE Perioperative partial-breast irradiation (PBI) with multicatheter interstitial brachytherapy (MIB) is less invasive and more convenient. This study aimed to compare ultrashort perioperative MIB-PBI and conventional MIB-PBI (cPBI). METHODS The trial was conducted on patients aged ≥ 40 years and those with T0–2 (≤ 3 cm), N0-mi, and negative margins on mammography. The locoregional recurrence (LRR) and toxicity rates were compared between ultrashort perioperative MIB-PBI (uPBI) at a dose of 25.2 Gy in 4 fractions and cPBI at a dose of 32 Gy in 8 fractions. RESULTS In total, 198 patients (151 with uPBI and 47 with cPBI) were evaluated. At a median follow-up of 20.1 months, one (0.66%) patient in the uPBI group had LRR. The 2-year ipsilateral breast tumor recurrence-free survival rates of the uPBI and cPBI groups were 98.7% and 100%, respectively. The highest toxicity grades were grade 1 in 23 (15.2%) and grade 2 in 2 (1.3%) patients in the uPBI group, and grade 1 in 8 (17.0%) and grade 2 in 1 (2.1%) patient in the cPBI group. None of the patients in the two groups presented with grade 3 and higher toxicities. The toxicity rates between the two groups did not significantly differ. Further, 22 (14.6%) patients in the uPBI group and 8 (17.0%) in the cPBI group, and 3 (2.0%) patients in the uPBI group and 1 (2.1%) in the cPBI had acute and late toxicities, respectively. Toxicities commonly occurred at ≤ 3 months after PBI. Nevertheless, the timing of toxicity development between the two groups did not significantly differ. CONCLUSIONS This preliminary report included a small sample size and had a short follow-up period. However, the local control and toxicity rates were similar between the uPBI and cPBI groups. Therefore, an ultrashort hypofraction schedule is feasible and safe for perioperative MIB-PBI.