Thermal ablative therapy for malignant liver tumors: a critical appraisal

The management of primary and secondary malignant liver tumors poses a great challenge to clinicians. Although surgical resection is the gold-standard treatment, most patients have unresectable malignant liver tumors. Over the past decade, various modalities of loco-regional therapy have gained much interest. Among them, thermal ablative therapy, including cryotherapy, microwave coagulation, interstitial laser therapy, and radiofrequency ablation (RFA), have been proven to be safe and effective. Despite the effective tumor eradication achieved within cryotherapy, the underlying freeze/thaw mechanism has resulted in serious complications that include bleeding from liver cracking and the 'cryoshock' phenomenon. Thermal ablation using microwave and laser therapy for malignant liver tumors is curative and is associated with minimal complications. However, this treatment modality is effective only for tumors <3 cm diameter. Radiofrequency ablation seems to be the most promising form of thermal ablative therapy in terms of a lower complication rate and a larger volume of ablation. However, its use is restricted by the difficulty encountered when using imaging studies to monitor the areas of ablation during and after the procedure. Moreover, the techniques of RFA need to be refined in order to achieve the same oncological radicality of malignant liver tumors as achieved by surgical resection. As each of the loco-regional therapies has its own advantages and limitations, a multidisciplinary approach using a combination of therapies will be the future trend for the management of malignant liver tumors.