90Yttrium (90Y) microspheres are 20- to 40-μ particles that emit beta radiation. Because the microspheres are delivered via the hepatic arterial route, the process can be considered “internal” rather than external radiation. The treatment algorithm is analogous to that followed with transarterial chemoembolization (TACE). Clinical history, physical examination, laboratory values and performance status are obtained. Patients are initially evaluated and staged using cross-sectional imaging techniques (computerized tomography [CT], magnetic resonance imaging [MRI], positron emission tomography [PET]). Once a patient is considered a possible candidate for therapy, evaluation using mesenteric angiography followed by treatment on a lobar basis is undertaken. Patients are followed clinically to assess toxicities and response prior to proceeding with treatment to the other lobe. A comprehensive review of the technical and methodological considerations in 90Y has been previously published (1–3).

Two devices are commercially available. Thera- Sphere (glass) was approved in 1999 by the Food and Drug Administration (FDA) under a Humanitarian Device Exemption (HDE) for the treatment of unresectable hepatocellular carcinoma (HCC) in patients with or without portal vein thrombosis who can have appropriately positioned hepatic arterial catheters (4). SIR-Spheres (resin) were granted full pre-marketing approval in 2002 by the FDA for the treatment of colorectal metastases in conjunction with intrahepatic floxuridine (FUDR) (5). Both devices have European approval for liver neoplasia and approvals in various Asian countries.

OVERVIEW

Patients with metastatic cancer to the liver from a colorectal primary tumor may be treated using surgical resection alone, providing a chance for long-term cure.