A Single-Institution Retrospective Study of Three-Fraction HDR Accelerated Partial Breast Irradiation

Area of Science:

• Oncology
• Radiation Oncology
• Surgical Oncology

Background:

• Accelerated partial breast irradiation (APBI) using high-dose-rate brachytherapy is a standard treatment, typically given in 10 fractions.
• A shorter, three-fraction regimen shows promise, but limited data exists for this approach.

Purpose of the Study:

• To report the experience and outcomes of patients treated with a three-fraction high-dose-rate brachytherapy APBI regimen, based on the TRIUMPH-T protocol.
• To evaluate the safety and efficacy of this shortened APBI schedule.

Main Methods:

• Retrospective analysis of 31 patients treated between 2016-2021 with a Strut Adjusted Volume Implant (SAVI) applicator.
• APBI delivered as 22.5 Gy in 3 fractions over 2-3 days, with toxicity assessed by CTCAE v5.0 and recurrence rates analyzed.

Main Results:

• Median follow-up was 31 months. No Grade 3 or higher toxicities were observed.
• Late Grade 1 and 2 toxicities occurred in 58.1% and 9.7% of patients, respectively.
• Four locoregional recurrences were noted (3 ipsilateral breast, 1 nodal), with breast recurrences in patients meeting "cautionary" criteria.

Conclusions:

• The three-fraction HDR brachytherapy APBI regimen is well-tolerated with low rates of severe toxicity.
• The observed recurrence rate suggests careful patient selection is crucial, especially pending longer-term follow-up data.