(245) Efficacy of Hippocampal Avoidance Whole Brain Radiation Therapy in Preventing Neurocognitive Dysfunction Induced by Radiation Therapy in Patients with Brain Metastases: A Systematic Review and Meta-Analysis
PhD Research Scholar Amrita School of Pharmacy, Amrita Vishwa Vidyapeetham Ernakulam, India
Background: About 50-90% of brain metastatic patients who receive radiation therapy are experiencing cognitive impairment after whole-brain radiation therapy. Hippocampal avoidance whole brain radiation therapy (HA-WBRT) is a new and exciting treatment modality to counteract radiation-induced cognitive dysfunction.
Objectives: This systematic review and meta-analysis aim to gather credible sources of comprehensive information on the efficacy, maximum and minimum dose to the hippocampus and contouring area on HAWBRT in preventing cognitive dysfunction.
Methods: A comprehensive review conducted in compliance with the PRISMA statement and systematic search was performed across five databases included PubMed®, Embase®, Scopus®, Cochrane Library® and ClinicalTrial.gov.in from inception until February 2022 to identify the literature that used HAWBRT for the prevention of neurocognitive dysfunction in brain metastatic patients. We included clinical trials and observational studies. Mantel Haenszel random-effect model was used for estimating pooled risk ratio for required outcomes.
Results: A total of seven eligible studies were selected in this review and that included 758 patients with brain metastases who received radiation therapy for final analysis. Overall, patients from five (71.4%) studies who were receiving whole brain radiation therapy (WBRT) had hippocampal contour area of 5 mm and one study (14.2%) reported a contouring area of 7mm to spare hippocampus. The maximum dose (D max) delivered to the hippocampus was 17 Gy in three studies, 16 Gy, and 12.61 Gy in other studies while the minimum dose delivered to the hippocampus was 10 Gy in two studies, 9 Gy in 2 studies, and 5.38 Gy in one study. Four studies (57.1%) reported significant (P= 0.04, P < 0.001, P= 0.001, and P = 0.019) improvement in neurocognitive functions mainly in the delayed recall domain due to HA-WBRT and comparatively higher than the conventional WBRT. Further, one study (14.2%) reported a significant correlation between hippocampal dosimetry and neurocognitive function changes (P=0.004) and there was no significant difference in the toxicity profile of HAWBRT compared to the WBRT as reported into two studies.
Conclusions: This review embraces the comprehensive evidence that HAWBRT in brain metastatic patients to prevent radiation-induced neurocognitive dysfunction had a significant beneficial effect on memory compared to the conventional WBRT. Hence, further inventions are required along with HAWBRT to get complete cognitive preservation.
