90Y microsphere (TheraSphere) treatment for unresectable colorectal cancer metastases of the liver: response to treatment at targeted doses of 135-150 Gy as measured by [18F]fluorodeoxyglucose positron emission tomography and computed tomographic imaging.

Purpose: The purpose of this phase II study was to determine the safety and efficacy of TheraSphere treatment (90Y microspheres) in patients with liver-dominant colorectal metastases in whom standard therapies had failed or were judged to be inappropriate.
Materials and Methods: Twenty-seven patients with unresectable hepatic colorectal metastases were treated at a targeted absorbed dose of 135-150 Gy. Safety and toxicity were assessed according to the National Cancer Institute's Common Toxicity Criteria, version 3.0. Response was assessed with use of computed tomography (CT) and was correlated with response on [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET). Survival from first treatment was estimated with use of the Kaplan-Meier method.
Results: Tumor response measured by FDG PET imaging exceeded that measured by CT imaging for the first (88% vs 35%) and second (73% vs 36%) treated lobes. Tumor replacement of 25% or less (vs >25%) was associated with a statistically significant increase in median survival (339 days vs 162 days; P = .002). Treatment-related toxicities included mild fatigue (n = 13; 48%), nausea (n = 4; 15%), and vague abdominal pain (n = 5; 19%). There was one case of radiation-induced gastritis from inadvertent deposition of microspheres to the gastrointestinal tract (n = 1; 4%). Three patients (11%) experienced ascites/pleural effusion after treatment with TheraSphere as a consequence of liver failure in advanced-stage metastatic disease. With the exception of these three patients whose sequelae were not considered to be related to treatment, all observed toxicities were transient and resolved without medical intervention.
Conclusion: TheraSphere administration appears to provide stabilization of liver disease with minimal toxicity in patients in whom standard systemic chemotherapy regimens have failed.