The role of cerebrospinal fluid cytology in radiotherapy planning for intracranial germinoma.

PURPOSE: The association between the cerebrospinal fluid cytology findings and the clinical features of patients with intracranial germinoma was investigated to determine whether cerebrospinal fluid cytology could be helpful in determining the optimal radiation treatment volume.

METHODS AND MATERIALS: Between 1976 and 1992, cerebrospinal fluid cytology was performed in 42 germinoma patients using a cytocentrifugation method. Forty patients received irradiation and 2 received chemotherapy with cisplatin and etoposide.

RESULTS: Cerebrospinal fluid cytology was positive in 22 of the 42 patients (52%). Dissemination via cerebrospinal fluid (intraventricular or spinal) was present at the initial diagnosis in eight (36%) of the 22 cytology-positive patients and none of the 20 negative patients. After treatment, cerebrospinal fluid dissemination developed in four (18%) of the cytology-positive patients and one (5%) of the negative patients. Two of the former four patients had received chemotherapy alone as initial treatment. Five patients with positive cytology received irradiation to a smaller volume than the cerebrospinal axis (primary tumor site plus spinal axis in three and whole brain in two), but they have not developed recurrence in the 4 to 14 years since therapy. The 5-year survival rate was 93% for the cytology-positive patients and 94% for the negative patients.

CONCLUSION: Cerebrospinal fluid cytology-positive patients have a higher risk of cerebrospinal fluid dissemination and it seems reasonable to give them low-dose (20-24 Gy) prophylactic craniospinal irradiation. When properly irradiated, the prognosis of cytology-positive patients is as good as that of negative patients.