GCT-10. CAN HIGH LEVEL SERUM hCG-β BE CONSIDERED EQUIVALENT TO A DIAGNOSIS OF CHORIOCARCINOMA IN PRIMARY CENTRAL NERVOUS SYSTEM GERM-CELL TUMOR?

BACKGROUND Primary central nervous system(CNS) choriocarcinoma(CC) is very rare and has the poorest prognosis among germ cell tumor (GCT). CC usually has extremely high level (HL) of serum beta-human chorionic gonadotropin (bhCG) over than 1,000 mIU/ml. Some studies assign HL bhCG cases to poor prognosis group even without biopsy. The purpose of this study was to find out if there was a good prognosis subset in the HL bh group. MATERIALS AND METHODS We analyzed 103 cases diagnosed with GCT from 1998 to 2019 in Hokkaido University Hospital and reviewed the literature of CNS CC and bhCG. Survival was assessed using Kaplan-Meier method and log-rank statistics between the group with CC component and that with no CC component but HL bhCG. RESULTS One out of 103 our cases was diagnosed as a mixed GCT with CC component and did not respond to treatment and died 9 months later. Two cases were treated as CC because of HL bhCG (1,226 and 2,739 mIU/ml) despite that the biopsy showed only germinomas and survived(105 and 37 months), that is, no CC component. Combining our cases with 69 cases in the literature, all 7 cases with no CC component but HL bhCG survived but the median survival of the other 65 cases with CC component was 38.2 months (P=0.02). CONCLUSION This study has a limitation of selection bias, however, it suggests that patients with no CC component but HL bhCG may have a better prognosis.