Hippocampal dosimetry correlates with the change in neurocognitive function after hippocampal sparing during whole brain radiotherapy: a prospective study

• Published in: Radiation oncology (London, England) England), 2015-12, Vol.10 (1), p.253-253, Article 253
• Main Authors: Tsai, Ping-Fang, Yang, Chi-Cheng, Chuang, Chi-Cheng, Huang, Ting-Yi, Wu, Yi-Ming, Pai, Ping-Ching, Tseng, Chen-Kan, Wu, Tung-Ho, Shen, Yi-Liang, Lin, Shinn-Yn
• Format: Article
• Language: English
• Subjects: Analysis; Batteries; Brain; Brain Neoplasms - radiotherapy; Care and treatment; Cognition - radiation effects; Cranial Irradiation - adverse effects; Cranial Irradiation - methods; Health aspects; Hippocampus - radiation effects; Humans; Metastasis; Neuropsychological Tests; Prospective Studies; Radiation Injuries - prevention & control; Radiometry; Radiotherapy; Radiotherapy Planning, Computer-Assisted; Radiotherapy, Intensity-Modulated
• ISSN: 1748-717X; 1748-717X
• DOI: 10.1186/s13014-015-0562-x

Whole brain radiotherapy (WBRT) has been the treatment of choice for patients with brain metastases. However, change/decline of neurocognitive functions (NCFs) resulting from impaired hippocampal neurogenesis might occur after WBRT. It is reported that conformal hippocampal sparing would provide the preservation of NCFs. Our study aims to investigate the hippocampal dosimetry and to demonstrate the correlation between hippocampal dosimetry and neurocognitive outcomes in patients receiving hippocampal sparing during WBRT (HS-WBRT). Forty prospectively recruited cancer patients underwent HS-WBRT for therapeutic or prophylactic purposes. Before receiving HS-WBRT, all participants received a battery of baseline neurocognitive assessment, including memory, executive functions and psychomotor speed. The follow-up neurocognitive assessment at 4 months after HS-WBRT was also performed. For the delivery of HS-WBRT, Volumetric Modulated Arc Therapy (VMAT) with two full arcs and two non-coplanar partial arcs was employed. For each treatment planning, dose volume histograms were generated for left hippocampus, right hippocampus, and the composite hippocampal structure respectively. Biologically equivalent doses in 2-Gy fractions (EQD2) assuming an alpha/beta ratio of 2 Gy were computed. To perform analyses addressing the correlation between hippocampal dosimetry and the change in scores of NCFs, pre- and post-HS-WBRT neurocognitive assessments were available in 24 patients in this study. Scores of NCFs were quite stable before and after HS-WBRT in terms of hippocampus-dependent memory. Regarding verbal memory, the corresponding EQD2 values of 0, 10, 50, 80 % irradiating the composite hippocampal structure with