Long-term results of intraoperative multicatheter breast implant (IOMBI) for accelerated partial breast irradiation (APBI) on early breast cancer patients

Background and purpose: Multicatheter breast brachytherapy is a standard technique for accelerated partial breast irradiation(APBI) in early breast cancer patients. Intraoperative multicatheter breast implant(IOMBI) followed by perioperative high-dose-rate brachytherapy(PHDRBT) offers a novel and advantageous approach. We present long-term oncological, toxicity, and cosmesis outcomes for a well-experienced single institution.

Materials and methods: Eligible women aged ≥ 40 years with clinically and radiologically confirmed unifocal invasive or in situ ≤ 3 cm breast tumors underwent IOMBI during breast-conserving surgery. Patients meeting APBI criteria by definitive pathologic results received 3.4 Gy × 10fx with PHDRBT. Patients not suitable for APBI received PHDRBT-boost followed by WBRT.

Results: A total of 171 patients underwent IOMBI during BCS, 120 patients(70.1 %) were suitable for APBI and 51(29.8 %) for anticipated PHDRBT-boost. The median age was 61 years(range: 40-78), the median tumor size was 1.1 cm(range: 0.2-3.5), with a histological diagnosis of invasive ductal carcinoma in 78.9 % and ductal in situ in 21.1 %. A median of 9 catheters (range:4-14) were used. For APBI, the median CTV and V₁₀₀ were 40.8 cc (range:8.6-99) and 35.4 cc (range:7.2-94). The median of healthy breast tissue irradiated represents 7.2 % (range:2.3-28 %) and the median local treatment duration was 10 days (range:7-16). With a median follow-up of 8.8 years (range:0.3-16.25), the 8-year local, locoregional, and distant control rates were 99 %, 98.1 %, and 100 %. G1-G2 late-toxicity rate was 53.4 %. Long-term cosmetic evaluation was excellent-good in 90.8 %.

Conclusion: IOMBI&PHDRBT program reports excellent long-term oncological outcomes, with a reduction from unnecessary irradiation exposure which translates into low long-term toxicity and good cosmesis outcomes, especially on well-selected APBI patients.

CITA DEL ARTÍCULO  Radiother Oncol. 2024 Mar 1:110193. doi: 10.1016/j.radonc.2024.110193