Free β-Subunit of Human Chorionic Gonadotropin in Serum Is a Diagnostically Sensitive Marker of Seminomatous Testicular Cancer

Abstract

We studied whether measurement of the free beta subunit of human chorionic gonadotropin (hCGbeta) in serum offers additional diagnostic information compared to determination of intact hCG alone in testicular cancer. We determined hCG and hCGbeta with ultrasensitive assays in 94 serum samples obtained preoperatively, 22 samples obtained during relapse, and 3687 samples obtained during routine follow-up of 351 patients with testicular tumors. In preoperative samples, isolated increases of hCGbeta were seen in 40% of the samples from seminoma patients (n = 42) and in 8% of those from patients with nonseminomatous testicular cancer (NSGCT) (n = 51). Both markers were increased in 12% of the seminoma and 71% of the NSGCT patients and were within reference intervals in 43% of the seminoma and 20% of the NSGCT patients. Specific determination of hCGbeta increased the frequency of marker-positive seminomas from 17% to 57% and of marker-positive relapses from 32% to 59% (n = 22). Theoretically, about 40% of marker-positive seminomas and relapses would have been missed with an assay measuring hCG and hCGbeta together. Preoperative hCG and hCGbeta concentrations correlated with stage, tumor histology, and disease-related mortality. Additionally, hCGbeta correlated with tumor size. hCGbeta is a diagnostically sensitive marker for testicular cancer. In patients with seminomatous testicular cancer, hCGbeta is superior to hCG, and in some NSGCT patients it provides additional information.