Distribution of metastatic disease in the brain in relation to the hippocampus: a retrospective single-center analysis of 6064 metastases in 632 patients

// San-Gang Wu 1, * , Ming-Yue Rao 2, * , Juan Zhou 3, * , Qin Lin 1 , Zi-Jing Wang 1 , Yong-Xiong Chen 4 , Zhen-Yu He 5 1 Department of Radiation Oncology, Xiamen Cancer Center, the First Affiliated Hospital of Xiamen University, Xiamen, People’s Republic of China 2 Department of Radiology, the First Affiliated Hospital of Xiamen University, Xiamen, People’s Republic of China 3 Department of Obstetrics and Gynecology, Xiamen Cancer Center, the First Affiliated Hospital of Xiamen University, Xiamen, People’s Republic of China 4 Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College of Xiamen University, Xiamen, People’s Republic of China 5 Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, People’s Republic of China * These authors have contributed equally to this work Correspondence to: Yong-Xiong Chen, e-mail: yxchen1962@xmu.edu.cn Zhen-Yu He, e-mail: hezhy@sysucc.org.cn Keywords: metastatic brain tumor, hippocampus, whole brain radiation therapy, age Received: June 12, 2015      Accepted: October 09, 2015      Published: October 19, 2015 ABSTRACT This study aimed to investigate the patterns of brain metastasis and to explore the risk factors affecting hippocampus metastasis (HM). We retrospectively analyzed the clinical information of patients with metastatic disease in the brain. The associations between clinicopathologic variables with HM and peri-hippocampal metastasis (PHM) were evaluated in univariate and multivariate regression analyses. A total of 632 patients with 6064 metastatic lesions were recruited into the present study. Of these, 4.1% (26/632) of patients developed HM, and 5.5% (35/632) of patients developed PHM. Only 0.5% (31/6064) of metastatic lesions were located in the hippocampus and 0.6% (37/6064) were in the PHM. Age ≤60 years was an independent risk factor for HM (odds ratio [OR]: 2.602, 95% confidence interval [CI]: 1.115–6.076, P = 0.027) and PHM (OR: 2.555, 95%CI: 1.229–5.310, P = 0.012) in univariate and multivariate analyses. The hippocampus is a rare site of brain metastasis. Younger patients (age ≤60 years) had increased risk of developing HM and PHM. The current study provides the opportunity to investigate the clinical feasibility of hippocampal sparing whole brain radiation therapy, especially in older patients.