Tissue expression of human chorionic gonadotropin beta predicts outcome in colorectal cancer: a comparison with serum expression.

Production of the glycoprotein hormone human chorionic gonadotropin beta (hCGbeta) has been associated with more aggressive behavior in non-trophoblastic tumors. In this study, the prognostic value of immunohistochemical hCGbeta expression was evaluated in 239 patients with colorectal cancer. Paraffin-embedded, formalin-fixed specimens were stained with hCGbeta-specific monoclonal antibody, and the results were compared with serum levels determined with an assay based on the same antibody. hCGbeta immunoreactivity was seen in 52 of 239 tumors (22%). The difference in survival time between patients with histologically hCGbeta-negative (median survival 94 months) and -positive (median survival 27 months) tumors was statistically significant (p = 0.014). The risk ratio during follow-up for patients with positive hCGbeta tissue expression was 1.65 (95% CI 1.11-2.46). In a Cox multivariate analysis, Dukes' stage, hCGbeta and age remained independent prognostic factors. There was moderate agreement between immunohistochemical and serum expression levels of hCGbeta (kappa = 0.30). Using a combination of histological and serum levels of hCGbeta, the difference between survival rates was highly significant (p < 0.001). The accuracy when predicting 5-year survival status with the combined results of serum and tissue expression was 1.3% higher compared to hCGbeta tissue expression alone. Our results show that hCGbeta expression in both tumor tissue and serum has prognostic significance independent of other clinicopathological variables. Positive tumor staining does not always occur together with elevated serum levels, and the prognostic accuracy can slightly be increased by combining the results.