P05.20 Laterality of hipoccampal metastases: MRI analysis of 260 patients with 2595 brain metastases

• Published in: Neuro-oncology (Charlottesville, Va.) Va.), 2018-09, Vol.20 (suppl_3), p.iii307-iii307
• Main Authors: Kazda, T, Kuklova, A, Belanova, R, Pospisil, P, Burkon, P, Hynkova, L, Slampa, P, Sana, J, Slaby, O, Jancalek, R
• Format: Article
• Language: English
• Subjects: Poster Presentations
• ISSN: 1522-8517; 1523-5866
• DOI: 10.1093/neuonc/noy139.346

Abstract Background Strategies for preservation of memory function in patients irradiated for brain metastases (BM) are currently widely investigated. Rare presence of BM within hippocampus (Hipp) enabled development of Hipp avoiding (HA) whole brain radiotherapy (WBRT). However, this HA zone are undertreated with increased risk of subsequent BM recurrence. Accumulating data are showing different post-radiotherapy changes in the left and the right hippocampus with a theoretical proposal of only unilateral (dominant - left) hippocampal sparing during WBRT. The aim of this retrospective study is to describe spatial distribution of BM on MRI in a cohort of 260 patients (2595 metastases) and to evaluate distribution separately in the left and right Hipp and in respective HA zones including evaluation of location of centre of metastatic mass (representing spatial location of original seed during metastasis grown). Material and Methods Consecutive patients with BM referred to radiotherapy from 2011 till 2014 were analyzed. For those with BM in proximity to Hipp, both Hipp were contoured (RTOG contouring atlas) and expansion of 5mm was performed to create HA zone. All BM in the proximity were delineated for recording of contact to Hipp or to HA zone. Results 260 pattients, mean age 57.8, most common primary diagnosis lung cancer, 51.9 % women. Median number of BM per patient was 3 with interquartile range 1–7, most commonly cerebellum and frontal lobes. BM within left and right temporal lobe were described in 23.5 and 23.9 % of patients. Overall, 7.7 % of patients developed BM within Hipp and 18.1 % within HA zone, representing 1.1 and 3.3 % of all BM, respectively. There was no statistically significant difference in the laterality of Hipp or HA BM. Left and right Hipp were involved in 4.6 and 5.6 % of patients (HA involvement in 11.5 and 10.4 % of patients, respectively). Left and right Hipp BM represented 0.5 and 0.6 % of all BM (HA zone BM 1.6 and 1.7 % of all BM). More patients presented with the centre of metastasis within left (15 patients) vs. right (6) HAZ reaching statistical significance. Conclusion No difference between involvement of left and right hippocampus on MRI was retrospectively observed in large consecutive cohort of 260 patients. Incidence of hippocampal BM in our cohort was higher comparing to previous studies. Superiority of HA WBRT will be evaluated in ongoing phase III clinical trials. Higher presence of BM within left HAZ comparing to