Intracranial germinoma: radiation therapy with tumor volume-based dose selection.

Purpose: To prospectively investigate whether intracranial germinomas, except large ones, can be cured with radiation doses lower than 50 Gy and to determine 10-year follow-up results.
Materials and Methods: Between 1985 and 1995, 38 patients with intracranial germinoma diagnosed histologically or with established criteria were enrolled. Total radiation doses to the primary tumor site were 36 Gy after total removal, 40 Gy for tumors less than 2.5 cm in diameter, 45 Gy for those 2.5-4.0 cm, and 50 Gy for those greater than 4.0 cm, with 1.6-1.8-Gy daily fractions. Patients underwent irradiation of the primary tumor site or cerebrospinal axis (20-24 Gy), depending on findings at diagnosis. No chemotherapy was allowed.
Results: All patients completed radiation therapy. Thirty-five patients were treated according to protocol, and three with relatively slow tumor regression or presence of a cyst received additional radiation (5-7 Gy, 50-52 Gy total). Ten-year overall and relapse-free survival rates were 91% and 95%, respectively. Two patients developed meningeal dissemination, but none had local failure. Treatment complications included chordoma in one patient and internal carotid artery occlusion in another. No treatment-related decline of performance status was observed in the other patients.
Conclusion: All tumor volume-based radiation doses were effective, without risk of local failure. Intracranial germinoma 4 cm or less in diameter can be cured with doses of 40-45 Gy. Investigation of further dose reduction seems worthwhile. Radiation therapy alone with these doses should be compared with ongoing chemotherapeutic protocols plus low-dose (24-30-Gy) irradiation in future studies.