Abstract
PURPOSE: To characterize radiotherapy (RT) use for brain metastases (BM) in British Columbia (BC) from January 2017 to December 2022. METHODS: Patients who received BM-directed RT were identified from the BC Cancer registry and RT delivery software. Patient demographics, disease characteristics, and RT details were collected for three periods: 2017–2018 (P1), 2019–2020 (P2), and 2021–2022 (P3). Chi-square and Kruskal-Wallis tests analyzed clinical factors associated with RT use. Kaplan-Meier overall survival was assessed. RESULTS: Among 2,797 patients, 3,317 RT courses were delivered. The most common primaries were non-small cell lung cancer (NSCLC) (49%), small cell lung cancer (SCLC) (18%), breast (9%), and gastrointestinal (7%). The proportion of BM RT per year decreased for SCLC but increased for breast, gastrointestinal, melanoma, gynecologic, and sarcoma cancers. RT courses delivered increased across periods (755, 1,217, and 1,345, respectively), with an increasing proportion of patients receiving ≥2 RT courses (10%, 13%, 16%, p=0.05). The most common dose was 20Gy in 5 fractions. Whole-brain RT (WBRT) declined (75%, 61%, 49% from P1 to P3), while focal RT, particularly stereotactic RT (SRT), increased from 148 courses (P1) to 416 (P3). Median survival from diagnosis was 14 months, and from first BM RT was 5 months. One-year OS from diagnosis improved (42%, 56%, 63%, p<0.01), but OS from first BM RT remained stable (30%, 32%, 33%, p=0.12). CONCLUSION: BM RT use in BC has increased, shifting from WBRT to focal RT, particularly SRT. While OS from diagnosis has improved, survival after BM RT remained stable.