Accelerated partial breast irradiation with high-dose-rate multicatheter brachytherapy: 30-year results of a phase 2 clinical trial.

PURPOSE: To report the 30-year updated results of accelerated partial breast irradiation (APBI) using multicatheter interstitial high-dose-rate (HDR) brachytherapy (BT).

METHODS AND MATERIALS: 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 7 fractions within 4 days was delivered to the tumor bed plus a 1-2 cm margin. The median follow-up time was 28.8 years 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 tumor recurrences were observed, for a 10-year and 30-year actuarial rate of 9.4%, and 12.6%, respectively. The 30-year DFS, CSS, and OS were 72.6%, 81.3%, and 46.6%, respectively. Fat necrosis requiring surgical intervention occurred in 1 woman (2.2%). Grade 3 fibrosis was observed in 1 patient (2.2%). No patient developed grade 3 late skin toxicity. Cosmetic results were rated excellent or good in 34 patients (75.6%).

CONCLUSIONS

Thirty-year results with APBI using HDR multicatheter interstitial implants continue to demonstrate excellent long-term local tumor control, survival, and cosmetic results with a low rate of late side effects.