Significance of human chorionic gonadotropin as a predictor of resistance to standard chemo-radiotherapy for pure germinoma

Intracranial pure germinomas in children generally respond well to standard chemo-radiotherapy. However, some patients are refractory to standard therapy and require additional treatment. To investigate the characteristics of this subgroup, we retrospectively analyzed the clinical features and treatment outcomes of a cohort of 21 patients with intracranial pure germinomas who were diagnosed between April 2002 and December 2016 at Ehime University Hospital in Japan. Pure germinoma diagnosis was verified by histological examination of the tumor after surgery, and all patients received standard chemo-radiotherapy. A suite of clinical features, including neuroimaging, human chorionic gonadotropin-β subunit (HCG-β), and α-fetoprotein (AFP) in the cerebrospinal fluid (CSF), as well as immunohistochemical expression of HCG-β, AFP, and Ki-67 in the tumor tissue were analyzed. Nineteen of the 21 patients had a complete response to standard chemo-radiotherapy without early recurrence of the tumors. Of these 19 patients, 17 did not have elevated CSF HCG-β levels or express HCG-β in the tumor tissue. However, the two patients who were refractory to standard therapy had elevated CSF HCG-β levels and expressed HCG-β in the tumor cells. These data suggest that patients with pure germinoma presenting with both an elevation of HCG-β in the CSF and HCG-β expression in the tumor tissue may be refractory to frontline treatment. These markers may predict aggressive germinoma and may ultimately facilitate the development of more effective treatment options.