To compare the clinical prognosis between surgical resection and local thermal ablation for patients with small liver cancer.

Clinical data of 4 565 patients with liver cancer who underwent surgical resection or local thermal ablation (microwave or radiofrequency ablation) in Surveillance, Epidemiology and End Results (SEER) database from 2004 to 2016 were retrospectively analyzed. The tumor diameter was ≤5 cm and no local or distant metastases was observed in these patients. All patients were divided into the surgical resection group (n=2 061) and local treatment group (n=2 504). All patients were classified into the Asian and non-Asian population according to different races. Survival analysis between two groups was performed by Kaplan-Meier method and Cox's proportional hazards regression model adjusted by inverse probability of treatment weighting (IPTW). The overall survival (OS) and cancer-specific survival (CSS) were considered as the outcome parameters.

After IPTW adjustment, the median OS and CSS in surgical resection group were 62 and 97 months, and were 40 and65 months in local treatment group, the OS and CSS in surgical resection group were significantly better than those in local treatment group (χ²=155.14, 78.41; P<0.05). Cox's multivariate regression analysis showed that the death risk in local treatment group was significantly higher than that in surgical resection group (HR=1.523, P<0.05). For patients with tumor diameter≤1 cm, the death risk did not significantly differ between the local treatment and surgical resection groups (HR=0.687, P>0.05). However, for patients with tumor diameter of 1-2 cm, 2-3 cm, 3-4 cm and 4-5 cm, the death risk in local treatment group was significantly higher than those in surgical resection group (HR=1.523, 1.279, 1.849, 1.922; P<0.05).

For patients with small liver cancer, the prognosis in patients undergoing surgical resection is better and the death risk is lower, compared with those undergoing local thermal ablation. The death risk does not significantly differ in patients with tumor diameter≤1 cm between two therapies.