Background and purpose: To report the 15-year updated results of accelerated partial breast irradiation (APBI) using multicatheter interstitial high-dose-rate (HDR) brachytherapy (BT).
Patients and methods: Forty-five prospectively selected patients with T1N0-N1mi, nonlobular breast cancer without the presence of an extensive intraductal component and with negative surgical margins were treated with APBI after breast-conserving surgery (BCS) using interstitial HDR BT. A total dose of 30.3 Gy (n=8) and 36.4 Gy (n=37) in seven fractions within 4 days was delivered to the tumour bed plus a 1–2 cm margin. The median follow-up time was 166 months for surviving patients. Local control, disease-free (DFS), cancer-specific (CSS), and overall survival (OS), as well as late side effects, and cosmetic results were assessed.
Results: Five (11.1%) ipsilateral breast tumour recurrences were observed, for a 5-year, 10-year, and 15-year actuarial rate of 4.4%, 9.4%, and 11.9%, respectively. The 15-year DFS, CSS, and OS was 75.4%, 86.2%, and 82.0%, respectively. Grade 3 fibrosis was observed in 1 patient (2.2%). No patient developed grade 3 teleangiectasia. Fat necrosis requiring surgical intervention occurred in 1 woman (2.2%). Cosmetic results were rated excellent or good in 36 patients (80%).
Conclusions: Fifteen-year results with APBI using HDR multicatheter interstitial implants continue to demonstrate excellent long-term local tumour control, survival, and cosmetic results with a low-rate of late side effects.