Implementation of hippocampal sparing whole brain radiotherapy in a resource-limited setting.

31 Background: Whole brain radiotherapy (WBRT) is a common treatment for brain metastases, but it often leads to cognitive decline due to hippocampal damage. Hippocampal avoidant technique has emerged to mitigate this cognitive toxicity. Our institution began hippocampal-avoidant WBRT (HA-WBRT) in 2021. We report our experience in implementing this technique in a resource-limited setting. Methods: We reviewed the medical records of patients who underwent HA-WBRT in our institution between January 2021 and March 2024. Clinical characteristics, treatment details, and dosimetry were reviewed. Hippocampal sparing was achieved using volumetric-modulated arc therapy (VMAT). Results: A total of 11 patients were included in the analysis. The median age was 57 years old, with a male-to-female ratio of 3:8. Most patients had metastatic breast cancer (7/11) followed by lung cancer (2/11). Among the breast cancer patients, 5 of them had HER2 positive subtype. Ten patients had good performance status (ECOG 0). Most patients (8/11) were treated with 20Gy in 5 fractions (with or without boost to tumor), and 3 patients with 30Gy in 10 fractions. The median time from CT simulation to treatment was 20.5 days. The target volume and organ-at-risk contouring were performed as per the AROMA trial (20Gy in 5 fractions) or RTOG 0933 study (30Gy in 10 fractions). The median beam-on time was 5.61 minutes. Nine patients completed WBRT with minimal acute toxicities. Two patients did not complete treatment due to a decline in performance status. Most patients were treated in multiple institutions thus, follow-up data was scarce. Conclusions: In our experience, HA-WBRT is feasible for suitable patients. Patients that benefit from this technique are younger, have good performance status, and have longer life expectancy e.g. breast primary. The challenges of implementing this treatment are a longer time for contouring and treatment planning, and longer treatment time compared with 2D or 3D WBRT. Long-term follow-up is needed to validate the benefit of this technique. Patient selection is key in implementing HA-WBRT in a resource-limited setting.