To analyze the spatial distribution of brain metastases in EGFR-mutant lung cancer and the risk of hippocampal metastasis.

Patients with lung cancer brain metastases diagnosed and treated in the Shanghai Cancer Center Fudan University from 2006 to 2016 were enrolled. The brain metastasis with positive mutation of EGFR gene was screened. The magnetic resonance images of the patients were reviewed and the distribution characteristics of brain metastasis were analyzed.

A total of 920 lung cancer patients with brain metastases were screened, 266 of whom had EGFR gene mutation detection, and 131(49%) were identified as EGFR gene mutations. Excluding 17 patients who did not have a head magnetic resonance examination in our hospital, a total of 114 patients and 738 lesions were enrolled in this study. The proportion of brain metastases distributed in each brain region was 22.8%, 19.5%, 22.0%, 13.4%, 3.3%, 16.7%, and 2.2% for frontal, temporal, parietal, occipital lobe, insula, cerebellum, and brainstem, respectively. The number of metastases and cases located in the hippocampus, <5 mm from the hippocampus, <10 mm from the hippocampus, and<15 mm from the hippocampus were 6(0.8%), 10(1.3%), 11(1.4%), and 14(1.8%), 5 cases (4.4%), 8 cases (7.0%), 9 cases (7.9%), and 11 cases (9.6%), respectively.

EGFR-mutant lung cancer brain metastasis is low risk in the hippocampus and its surrounding 15 mm.

Lung cancer, brain metastasis; Brain metastasis, hippocampus