Radiation Therapy of Intracranial Germinomas: Optimum Radiation Dose and Treatment Volume / 대한방사선종양학회지

ABSTRACT

PURPOSE: To evaluate the possibility of decreasing the radiation dose and to determine optimum treatment volume in intracranial germinomas. MATERIALS AND METHODS: Forty five patients with pathologically-verified or presumed germinomas by a radiosensitivity test who had been treated with radiotherapy (RT) alone between 1971 and 1992 were retrospectively analyzed. The average age was 17.2 years with 68.9% of the patients being between the ages of 10-20. The male and female ratio was 2.21. The locations of the primary tumors were at the pineal regions in 14 patients; the suprasellar regions in 12 patients; and multiple sites in 12 patients. Treatment volumes varied from a small local field (10) to the whole brain (7) or entire neuroaxis irradiation(28). All the cases after 1982 received craniospinal irradiation (CSI). Radiation doses were 41-59 Gy (median 48.5 Gy) to the primary tumor site and 19.5-36 Gy (median 24 Gy) to the neuroaxis. The median follow-up period was 82 months with a range of 2-260 months. RESULTS: All the patients showed complete response after RT. Four patients sufferred from recurrence 14, 65, 76, and 170 months after RT, respectively, and two patients died with intercurrent disease. One of four recurrent cases was salvaged by re-irradiation. Therefore, a 5 and 10 year overall survival was 95.3 % and 84.7 % respectively. Five and ten year disease-free survival was 97.6 % and 88.8 % respectively. All the recurrences occurred in the patients who received local RT (3/10) or whole brain RT (1/7) with a radiation dose of 48-50 Gy. None of the patients who received CSI suffered recurrence. There was no recurrence among the 15 patients who received < or = 45 Gy to the primary site and the 18 patients who received < or = 24 Gy (6 patients received 19.5 Gy) to the neuroaxis. CONCLUSION: CSI is recommended for the treatment of intracranial germinomas. The radiation dose can be safely decreased to < or = 45 Gy on a primay tumor site and 19.5 Gy on the spine.