KEY POINTS
- This single-institution retrospective series included 922 breast cancers treated with perioperative multicatheter partial-breast brachytherapy from 2010-2025. Typical candidates were aged ≥40 years with tumors ≤3 cm, negative sentinel nodes, and a high likelihood of negative surgical margins.
- Perioperative HDR brachytherapy delivered 32 Gy in 8 fractions or 25.2 Gy in 4 fractions with Iridium-192. If final pathology showed unfavorable features such as positive margins, positive nodes, or invasive lobular histology, subsequent whole-breast irradiation could be added at 50 Gy in 25 fractions or 42.5 Gy in 16 fractions, with the initial partial-breast treatment considered the boost.
- Only 26 of 922 cases (2.8%) required subsequent whole-breast irradiation. The main reasons were margin status in 50.0%, nodal involvement in 30.8%, and lobular histology in 7.7%.
- At a median follow-up of 7.2 years, there were no local relapses in the sequential whole-breast cohort. Five-year local-relapse-free survival was 100% vs 98.1% with brachytherapy alone (p = 0.75), while disease-free survival was 95.2% vs 97.0% (p = 0.80).
- Ten-year local-relapse-free survival remained 100% after sequential whole-breast irradiation versus 96.4% after brachytherapy alone. The escalated cohort was highly selected and contained substantially more positive/close margins (30.8% vs 6.0%, p < 0.001) and node-positive disease (30.8% vs 1.7%, p < 0.001).
- No grade ≥3 adverse events occurred in either cohort. Symptomatic seroma occurred in 7.7% vs 2.1% after sequential WBI versus brachytherapy alone (p = 0.12), while surgical-site infection occurred in 0% vs 3.4% (p = 1.0).
- Cumulative dose reconstruction was available for 15 sequentially treated patients. Median cumulative EQD2 was 54.7 Gy for skin Dmax, 53.7 Gy for chest-wall/rib Dmax, and ipsilateral lung V20 was 12.3%. For left-sided tumors, median heart D2cc was 3.6 Gy EQD2.
CLINICAL TAKEAWAY
Adding whole-breast irradiation after perioperative partial-breast brachytherapy appears technically feasible when unexpected adverse pathology emerges, with reassuring long-term local control and cumulative OAR doses in this series. However, the sequential cohort included only 26 highly selected patients and WBI indications were not predefined, so these data do not establish this strategy as an alternative standard.