Potential Interventional and Ablation Therapies for Head and Neck Tumors

Non-resectable and metastatic tumors present a difficult challenge for veterinarians and pet owners. The relatively limited efficacy of intravenous chemotherapy for macroscopic disease, and the cost and morbidity associated with radiation therapy have stimulated the search for additional therapeutic options. While surgery can be successfully performed in the head and neck, this area provides unique challenges such as the proximity to important neurovascular structures, high motion environment, the nasal, oral and sinus cavities, the rich and abundant blood supply providing frequent opportunities for massive hemorrhage and limited visualization, and the owners’ reliance upon cosmetic results. These limitations often prevent clean margins from being achieved resulting in combined modalities needed to treat, or rather palliate, the often large tumors presented in this region. Similar difficulties in human oncology have inspired various creative, image-guided, regional tumor therapies in the continuously developing subspecialty of interventional radiology (IR). IR involves the use of contemporary imaging techniques such as fluoroscopy and ultrasonography to selectively access vessels and other structures in order to deliver different materials for therapeutic reasons. In the past two decades, IR techniques have expanded considerably with both vascular and non-vascular procedures being performed routinely in humans. Specifically, IR techniques are being increasingly utilized to help palliate humans with cancer (interventional oncology) in which traditional therapies have failed or have been demonstrated to provide little benefit. These techniques are particularly useful in cases of regional disease in order to maximize local therapy and minimize systemic toxicity. While results have been variable, regional techniques such as percutaneous tumor ablation, intra-arterial chemotherapy, transcatheter arterial embolization/ chemoembolization, and/or palliative stenting have been demonstrated to improve survival times, disease-free intervals, recurrence rates, or completeness of tumor necrosis (Additional references available from author upon request). All of these techniques are currently in their infancy in veterinary oncology, however not unlike the situation in our human counterparts, Interventional Oncology is poised to become the fourth pillar of veterinary oncology. A number of minimally invasive options exist for use in dogs with head and neck tumors. Most of these are still considered experimental in veterinary patients and include stenting for malignant obstructions, local delivery of chemotherapy (intra-arterial chemotherapy), transarterial embolization (TAE) for hemorrhage or tumors, transarterial chemoembolization (TACE) with or without drug-eluting brads (DEBs), and percutaneous ablation.