Impact factors for microinvasion in patients with hepatocellular carcinoma: possible application to the definition of clinical tumor volume

PURPOSE

To evaluate the degree of invasion of hepatocellular carcinoma (HCC) microscopically that will provide a potential application for gross tumor volume to clinical tumor volume (GTV-to-CTV) expansion.

METHODS AND MATERIALS

From January 2002 to January 2006, 149 HCC patients were selected from those who had undergone surgical resection. Pathology slides and clinical data of all patients were reviewed, including platelet counts, serum alpha-fetoprotein (AFP) levels, degree of liver cirrhosis, tumor size, capsular status, portal vein invasion, TNM stage, and histologic tumor grade. The distance between the tumor margin (or fibrous capsule) and the invasive lesions was measured by senior pathologists.

RESULTS

Of these 149 patients, 79 (53.0%) patients presented with tumor microinvasion between 0.5 and 4 mm. This degree of microinvasion was inversely correlated with lower platelet counts and positively correlated with higher AFP levels, larger tumor sizes, portal vein invasion, and advanced TNM stage. Microinvasion distances less than or equal to 2 mm were found in 96.1% of patients (74/77) with tumor dimensions less than or equal to 5 cm and in 94.5% of patients (85/90) with AFP levels less than 400 microg/l.

CONCLUSIONS

Based on our study findings, GTV-to-CTV expansions of 4 mm for HCC are required to conceal the gross tumor and any microscopic disease with 100% accuracy. Tumor size and AFP levels are the simplest indicators for determining the GTV-to-CTV distance for HCC.