Intracranial, Extracranial and Spinal Tumor Embolizations
Tumor Embolization is a cancer therapy that helps treat tumors by blocking the blood vessels that supply them. Many tumors such as meningiomas, hemangioblastomas, renal cell metastases, and paragangliomas are hypervascular, thus making surgical resection more difficult and time consuming. Performing the embolization prior to surgery assists in the resection by reducing blood loss and improving visualization of the surgical site. In patients who are not candidates for surgical resection, intra-arterial embolization can provide palliative therapy.
The methods of embolization include transarterial, direct puncture, and a combination of the 2 approaches. Tumor embolization is achieved by the occlusion of the very small vessels within a tumor, while sparing blood supply to normal adjacent tissue. Liquid and particulate embolic materials are effective in penetrating small vessels.
Most tumor embolizations are performed via the external carotid arterial supply. The time involved in surgical resection may vary depending on tumor type, characteristics, and degree of devascularization. The materials commonly used include poly vinyl alcohol (PVA) particles of varying sizes as well as pledgets of gelatin sponge and microfibrillar collagen. Liquid embolization agents include, n-butylcyanoacrylate, Onyx, and ethanol. Occlusion of large vessels may require use of either pushable or detachable coils. They can be an ideal embolization solution for tumors with intra-tumoral shunting. Coils with bioactive components can provide a nidus for thrombosis and eventual occlusion of the vessel. As with nBCA embolization, coils provide proximal occlusion of the blood supply to the tumor bed without the embolization of the tumor vasculature itself. Therefore, surgical resection should follow coil embolization to minimize the development of collateral blood channels.