Detection of beta-human chorionic gonadotropin expressing cells by nested reverse transcriptase-polymerase chain reaction in the peripheral blood stem cells of patients with advanced germ cell tumor.

Abstract

We investigated whether peripheral blood stem cells (PBSCs) were contaminated by tumor cells. A total of 13 patients with advanced testicular cancer underwent PBSC transplantation at our institute. Nested reverse transcriptase-polymerase chain reaction using primers specific for beta-human chorionic gonadotropin (beta-HCG) or alpha-fetoprotein (AFP) detected 1 beta-HCG or AFP producing cell in 1 x 10(6) PBSCs. Although AFP messenger (m) RNA was not identified in any of the 13 patients, beta-HCG mRNA was detected in 7. All patients with beta-HCG mRNA in PBSCs had elevated serum beta-HCG before treatment. Three patients with a normal beta-HCG range before treatment did not have beta-HCG mRNA in the PBSCs. The serum beta-HCG level in the patients whose PBSCs were contaminated with tumor cells was significantly higher than in patients whose PBSCs contained no tumor cells. Four of the 7 patients with beta-HCG mRNA in PBSCs eventually died of cancer, whereas those whose PBSCs were not contaminated with tumor cells survived without disease. Patients with elevated serum beta-HCG levels are likely to have PBSCs contaminated by tumor cells. Moreover, the prognosis of patients with tumor cells in the PBSCs is poor.