Introduction
Despite limited evidence, technique efficacy and complications may be important short-term outcomes after ablation for hepatocellular carcinoma (HCC). We aimed to report these outcomes after ablation as the first surgical intervention for HCC.

Methods
This nationwide cohort study was based on data from the Danish Liver and Biliary Duct Cancer Database and medical records. Variables associated with outcomes were investigated using logistic regression.

Results
From 2013 to 2023, 433 patients were included of which 79% were male, 73% had one tumor, and 90% had cirrhosis. Complete ablation was achieved after percutaneous, laparoscopic, and open approach in 84%, 100%, and 96% of the procedures, respectively. Most patients did not experience complications (76%). Open ablation compared with percutaneous was associated with higher risk of complications in multivariable adjusted analysis (Clavien-Dindo grade 2–5 (odds ratio 5.34, 95% confidence interval [2.36; 12.08]) and 3B-5 (5.70, [2.03; 16.01]), and lower risk of incomplete ablation (0.19 [0.05; 0.65]). Number of tumors ≥3 was associated with a higher risk of incomplete ablation (3.88, [1.45; 10.41]). Tumor diameter ≥3 cm was associated with increased risk of complications grade 2–5 (2.84, [1.29; 6.26]) and 3B-5 (4.44, [1.62; 12.13]). Performance status ≥2 was associated with risk of complications grade 3B-5 (5.98, [1.58; 22.69]). Tumor diameter was not associated with technique efficacy.

Conclusion
Open ablation had a higher rate of complete ablation compared with percutaneous but was associated with a higher risk of complications. Tumor diameter ≥3 cm and performance status ≥2 were associated with a higher risk of complications.