Patients can be included in the study if they have one or more malignant liver tumors unsuitable for resection and thermal ablation (due to proximity of major vessels or bile duct) or other established liver directed therapies.

Prior to inclusion all potential participant will be evaluated by the local multidisciplinary team, to insure fulfillment of the above-mentioned criteria. In general, the included patient will have tumors with <1 cm of margin to major hepatic vessels or bile ducts, thereby not allowing for conventional treatments because of risk of i.e. hemorrhage, biliary tract damage, liver failure or ineffective ablation due to heat sink.

IRE will be done under general anesthesia as an in-patient procedure. Patients will be observed for at least 24 hours after IRE.

Patients will attend CT scans 1, 3, 6, 9, 12, 18, 24, 36, 48 and 60 months post-IRE according to national guidelines (for follow-up after radiofrequency ablation (RFA)). Patients will attend the out-patient clinic after 1, 3, 6, 9, 12, 18 and 24 months. During the follow-up period, patients will be asked to fill out electronic forms monitoring pain, quality of life and nutritional status. After 24 months the patients will only be followed with CT scans in accordance with the mentioned schedule. Data collection for scientific purposes will stop when the last included patient has been followed for at least 24 months or when the study period concludes.

In case of multiple liver tumors, where a conventional treatment approach is not possible due to a single lesion being too close to major vessels or bile ducts, IRE may be used in conjunction to conventional therapy.