PET imaging improves assessment of therapy in hepatocellular carcinoma

CONTEXT: Intra-arterial therapy with beta-irradiating yttrium (90Y) microspheres (Therasphere) has demonstrated significant therapeutic benefit in patients with hepatocellular carcinoma. Researchers led by Dr. Robert J. Lewandowski at Northwestern Memorial Hospital in Chicago tested the efficacy and safety of 90Y microspheres on unresectable colorectal metastases to the liver. Scientists evaluated response to treatment using CT and FDG-PET, comparing response between these two modalities.

RESULTS: Twenty-seven patients with unresectable hepatic colorectal metastases were treated with 90Y microspheres (target radiation doses of 135 to 150 Gy). Following Common Toxicity Criteria from the National Cancer Institute, researchers noted minimal toxicity from treatment. Metastatic lesions showed a higher percentage of favorable response when measured by FDG-PET imaging when compared with CT imaging (88% versus 35% for the first lobe and 73% versus 36% for the second lobe treated).

IMAGE: Top: Pre- (A) and post- treatment (B) CT demonstrates no significant change in size of multiple hepatic metastases. Bottom (same patient): (C) Pretreatment PET shows multiple cannonball hypermetabolic metastases, and (D) post-treatment PET shows near complete metabolic response. Patient had a 94% reduction in serum CEA levels.

IMPLICATIONS: Metastatic liver disease may be stabilized with minimal toxicity through the administration of 90Y. Compared with CT, FDG-PET scans enhance assessment of therapy by providing details on tumor's metabolic activity. Working with oncologists, a group of interventional radiologists hope to have their therapies included in more controlled studies, according to Lewandowski.