Safety and feasibility of accelerated consolidative gamma knife radiotherapy following brain metastases resection.

Abstract

e14020 Background: Consolidative radiotherapy is the standard of care following surgical resection of brain metastases; however, the optimal timing remains controversial. The authors report their institutional experience evaluating the safety, feasibility, and clinical outcomes of accelerated postoperative stereotactic radiosurgery (SRS). Methods: This is a retrospective analysis of a prospectively maintained SRS registry at a tertiary academic medical center. Patients with brain metastases who presented between 2013 and 2025 and underwent surgical resection followed by postoperative SRS were included. The Early group comprised patients who received consolidative SRS within 14 days of surgical resection. For comparison, the most recent 50 patients in the registry who were treated with consolidative SRS between 15 and 30 days postoperatively were selected as the standard group. A 10Gy single fraction constraint was applied to the skin for SRS planning. Results: The early group included 146 patients who underwent surgical resection of 155 brain metastases. Baseline demographic characteristics were comparable between the early and standard groups. Both cohorts had similar durations of clinical and radiographic follow-up; however, the early group had a significantly longer postoperative length of stay (5.2 vs 3.0 days, p = 0.001). Primary cancer types were similarly distributed between groups, except for breast cancer, which tended to be more prevalent in the standard group (7.5% vs 16.0%, p = 0.08). Cerebellar metastases were more common in the standard group (13.5% vs 28.8%, p = 0.012). Hypofractionated regimens (2, 3, or 5 fractions) were employed in both cohorts (7.7% vs 15.1%, p = 0.10). The Early group had a significantly smaller mean preoperative tumor volume (15.0 vs 21.8 cm³, p = 0.003) and a smaller mean postoperative cavity prescription isodose volume (26.2 vs 34.7 cm³, p = 0.042). In contrast, postoperative cavity volume, number of additional lesions treated during the same SRS session, total treatment volume, and total prescription isodose volume were similar between the two groups. The highest and lowest isodose lines traversing the surgical wound at the deepest and most superficial levels, respectively, were comparable between the groups, although the scalp volume receiving >10 Gy tended to be lower in the early group (0.8 vs 2.2 cm³, p = 0.09). There were no statistically significant differences in wound-healing complications (3.4% vs 2.0%, p = 0.60), local recurrence (12.4% vs 20.0%, p = 0.70), or rates of radiation necrosis (14.7% vs 17.1%, p = 0.70). Conclusions: Accelerated postoperative consolidative SRS can be well tolerated, with no observed increase in wound-healing complications or radiation necrosis. Completion of consolidative radiation treatment early post-operatively may facilitate earlier return to systemic therapy and should be considered when possible.