Survival outcomes and toxicity profile after CT-guided HDR brachytherapy (interventional radiotherapy) for liver oligometastases in breast cancer patients: The BRALIBREST real world multicenter study.

Abstract

To evaluate efficacy and tolerability of high-dose-rate brachytherapy (HDR-BT) for breast-cancer (BC) liver oligometastases. We included patients with oligometastatic breast cancer, defined as having ≤ 5 liver metastases, WHO performance status <3, tumor diameter <10 cm. Patients were excluded if tumor location prevented applicator placement or adequate dosing of CT-guided HDR-BT. End-points were overall survival (OS), progression-free survival (PFS), locoregional control (LRC), modified PFS (mPFS), freedom from subsequent systemic-therapy line and radiological response - disease control rate and objective response rate (ORR). Univariate (UVA) and multivariate (MVA) Cox models explored clinicopathologic and dosimetric predictors. A total of 107 patients were included; 61 % were treated for a single lesion, and 39 % for multiple. The median prescribed dose was 20 Gy (15-25 Gy). The median OS was 37 months (2-year: 60 %). Median PFS, LRC, mPFS, and freedom from subsequent systemic-therapy were 13, 19, 15, and 22 months. Disease control rate improved from 93 % at 6 months to 98 % at 12, while ORR rose from 63 % to 85 %. On UVA, repeat and induced oligometastatic disease predicted superior OS, while extrahepatic spread, liver volume >10 cm³, and lesion diameter >4 cm were adverse. Delivering ≥25 Gy to 90 % of GTV halved the risk of death. Only grade 1-2 acute toxicities were observed; no grade ≥3 events, with 8 % late grade 3 hepatic toxicity. HDR-BT appears to be an effective metastasis-directed therapy for selected patients with BC liver oligometastases.