Ami Kavi1, Jason Gurewitz2, Carolina G Benjamin3, Joshua S Silverman4, Kenneth Bernstein5, Monica Mureb6, Cheongeun Oh7, Erik P Sulman4, Bernadine Donahue8, Douglas Kondziolka9. 1. Department of Radiation Oncology, State University of New York Downstate Health Sciences University, Brooklyn, USA; Department of Radiation Oncology, Maimonides Cancer Center, Brooklyn, USA. Electronic address: Akavi13@gmail.com. 2. Marian University College of Osteopathic Medicine, USA; Department of Radiation Oncology, NYU Grossman School of Medicine, New York, USA. 3. Department of Neurosurgery, University of Miami, Miami, USA. 4. Brain and Spine Tumor Center, Laura and Isaac Perlmutter Cancer Center, NYU Langone Health, New York, USA; Department of Radiation Oncology, NYU Grossman School of Medicine, New York, USA. 5. Brain and Spine Tumor Center, Laura and Isaac Perlmutter Cancer Center, NYU Langone Health, New York, USA; Department of Radiation Oncology, NYU Langone Health, New York, USA. 6. Department of Neurosurgery, Westchester Medical Center, Valhalla, USA. 7. Department of Population Health, Division of Biostatistics, NYU Langone Health, New York, USA. Electronic address: ohc03@nyumc.org. 8. Brain and Spine Tumor Center, Laura and Isaac Perlmutter Cancer Center, NYU Langone Health, New York, USA; Department of Radiation Oncology, NYU Grossman School of Medicine, New York, USA; Department of Radiation Oncology, Maimonides Cancer Center, Brooklyn, USA. 9. Department of Neurosurgery, NYU Grossman School of Medicine, New York, USA; Brain and Spine Tumor Center, Laura and Isaac Perlmutter Cancer Center, NYU Langone Health, New York, USA; Department of Radiation Oncology, NYU Grossman School of Medicine, New York, USA.
Abstract
PURPOSE/ OBJECTIVES: To report our dosimetric analysis of the hippocampi (HC) and the incidence of perihippocampal tumor location in patients with ≥25 brain metastases who received stereotactic radiosurgery (SRS) in single or multiple sessions. MATERIALS/ METHODS: Analysis of our prospective registry identified 89 patients treated with SRS for ≥25 brain metastases. HC avoidance regions (HA-region) were created on treatment planning MRIs by 5 mm expansion of HC. Doses from each session were summed to calculate HC dose. The distribution of metastases relative to the HA-region and the HC was analyzed. RESULTS: Median number of tumors irradiated per patient was 33 (range 25-116) in a median of 3 (range1-12) sessions. Median bilateral HC Dmin (D100), D40, D50, Dmax, and Dmean (Gy) was 1.88, 3.94, 3.62, 16.6, and 3.97 for all patients, and 1.43, 2.99, 2.88, 5.64, and 3.07 for patients with tumors outside the HA-region. Multivariate linear regression showed that the median HC D40, D50, and Dmin were significantly correlated with the tumor number and tumor volume (p < 0.001). Of the total 3059 treated tumors, 83 (2.7%) were located in the HA-region in 57% evaluable patients; 38 tumors (1.2%) abutted or involved the HC itself. CONCLUSIONS: Hippocampal dose is higher in patients with tumors in the HA-region; however, even for patients with a high burden of intracranial disease and tumors located in the HA-regions, SRS affords hippocampal sparing. This is particularly relevant in light of our finding of eventual perihippocampal metastases in more than half of our patients.
PURPOSE/ OBJECTIVES: To report our dosimetric analysis of the hippocampi (HC) and the incidence of perihippocampal tumor location in patients with ≥25 brain metastases who received stereotactic radiosurgery (SRS) in single or multiple sessions. MATERIALS/ METHODS: Analysis of our prospective registry identified 89 patients treated with SRS for ≥25 brain metastases. HC avoidance regions (HA-region) were created on treatment planning MRIs by 5 mm expansion of HC. Doses from each session were summed to calculate HC dose. The distribution of metastases relative to the HA-region and the HC was analyzed. RESULTS: Median number of tumors irradiated per patient was 33 (range 25-116) in a median of 3 (range1-12) sessions. Median bilateral HC Dmin (D100), D40, D50, Dmax, and Dmean (Gy) was 1.88, 3.94, 3.62, 16.6, and 3.97 for all patients, and 1.43, 2.99, 2.88, 5.64, and 3.07 for patients with tumors outside the HA-region. Multivariate linear regression showed that the median HC D40, D50, and Dmin were significantly correlated with the tumor number and tumor volume (p < 0.001). Of the total 3059 treated tumors, 83 (2.7%) were located in the HA-region in 57% evaluable patients; 38 tumors (1.2%) abutted or involved the HC itself. CONCLUSIONS: Hippocampal dose is higher in patients with tumors in the HA-region; however, even for patients with a high burden of intracranial disease and tumors located in the HA-regions, SRS affords hippocampal sparing. This is particularly relevant in light of our finding of eventual perihippocampal metastases in more than half of our patients.