Prognosis of intracranial germinoma with syncytiotrophoblastic giant cells treated by radiation therapy

Purpose: The limited information in the literature suggests that intracranial germinoma with syncytiotrophoblastic giant cells (STGC) producing human chorionic gonadotropin (HCG) is associated with a higher recurrence rate compared with pure germinoma producing no HCG. To determine whether the poorer prognosis for germinoma with STGC is an inevitable finding, we retrospectively analyzed data for our patients. Methods and Materials: Data were analyzed for 44 patients who had pretreatment examination of HCG titers in the serum and/or cerebrospinal fluid 9CSF) and underwent radiotherapy between 1978 and 1993. The diagnosis of germinoma was made histologically in 19 patients and clinically in 25 according to the established criteria. The treatment volume was the primary tumor site in 9 patients, the cerebrospinal axis in 29, and other in 6. The median follow-up period was 90 months. Results: Twenty (45%) of the 44 patients had elevated HCG titer. The abnormal HCG levels ranged from 4.9 to 189 mIU/ml (median: 18 mIU/ml) in serum and 8.2 to 660 mIU/ml (median: 26 mIU/ml) in CSF. No difference was found between the two groups in any patient or treatment characteristics including tumor size and incidence of CSF dissemination. The mean radiation dose to the primary tumor site was 46.4 Gy for pure germinoma and 47.5 Gy for germinoma with STGC. The 10-year survival and relapse-free survival rates were both 100% for the patients with germinoma with STGC and both 89% for those with pure germinoma. Among these patients, only two with pure germinoma developed recurrence. Conclusions: Our data suggest that the prognosis of intracranial germinoma with STGC treated with adequate radiation therapy does not differ from that of pure germinoma. Our current policy of delivering 40-45 Gy for tumors < 4 cm in diameter seems to be a reasonable treatment for germinoma with STGC