Objective To compare the efficacy and safety between thermal ablation combined with synchronous transcatheter arterial chemoembolization(TACE)and TACE in patients with liver metastasis of neuroendocrine tumors of different pathologic grades.Methods A retrospective analysis was performed on patients with liver metastases of neuroendocrine tumors admitted to Department of Interventional Radiology,Zhongshan Hospital,Fudan University from Nov 1,2006 to Jul 31,2022.The patients were divided into synchronous ablation group and TACE group according to treatment mode and subgroups according to pathological grade.The lesions were evaluated by postoperative imaging examination.The patients were followed up until Jul 31,2023,and surgery-related complications were recorded.The endpoint of prognosis were progression-free survival(PFS)and overall survival(OS).Results A total of 86 patients with neuroendocrine tumor were collected,including 34 patients in simultaneous ablation group and 52 patients in TACE group.According to WHO classification,21 patients at G1 stage,45 patients at G2 stage and 20 patients at G3 stage were included.No serious postoperative complications occurred in all patients.The median OS was 47.0(95%CI:31.2-62.8)months in the TACE group and 56.0(95%CI:8.3-73.4)months in the synchronous ablation group,with no statistical difference between the two groups(P=0.50).The median PFS was 18.0(95%CI:6.0-30.0)months in the TACE group and 29.0(95%CI:10.0-48.0)months in the synchronous ablation group,with no statistical difference between the two groups(P=0.22).Of the 45 patients at G2 stage,27 received TACE with a median OS of 47.0 months,and 18 received synchronous ablation with a median OS of 59.0 months,and there was no statistical difference between the two groups(P=0.45).The median PFS was 12.0 months in the TACE group and 32.0 months in the synchronous ablation group,and the difference between the two groups was statistically significant(P=0.03).Conclusion Comparing with TACE,simultaneous ablation can delay disease progression in patients with liver metastasis of neuroendocrine tumors to a certain extent and has good safety,especially for patients with liver metastases of neuroendocrine tumors with intermediate or low grade.