RECURRENT OLIGODENDROGLIOMAS AFTER FIRST CHEMO-RADIATION THERAPY RESPONDED REMARKABLY TO RE-RADIATION

Abstract Oligodendrogliomas with 1p/19q-codeletion are relatively slow progressive tumors that show good response to chemo-radiation therapy after resection. The median survival is about 15 years regardless of WHO grade, although recurrences are mostly inevitable and there is no standard treatment for recurrence. We experienced 5 oligodendroglioma cases who underwent re-radiation for recurrent tumors after chemo-radiation treatment. We retrospectively investigated those for response to re-radiation, the duration from first radiation to second radiation, and Karnofsky Performance Status (KPS) before and after the re-radiation. Patients were all male; the median radiation dose for primary tumor was 60Gy (54-60Gy), the median age at first radiation was 46 years (35-59), the median duration from the first radiation to re-radiation was 65 months (range 18-116 months), and the median follow-up period after re-radiation was 15 months (1-39 months). In all 5 cases, tumors showed good response to re-radiation. In 3 of the 5 cases, tumor recurred in corpus callosum and/or lateral side of cerebral hemisphere or basal ganglia contiguous with primary tumor sites and were radiated by IMRT (50Gy/25fr) . In 2 cases, tumors recurred around the fourth ventricle and posterior fossa and underwent conventional radiation (54Gy/30fr and 30Gy/10fr). In 2 of the 5 cases, the tumors re-recurred 24 months later after re-radiation, but the KPS were maintained until re-recurrence. For oligodendrogliomas, re-radiation therapy appears to be very effective to recurrent tumors after first chemo-radiation. Although evaluation for longer-term side effects is to be examined, re-radiation appears to be a good option for recurrent oligodendrogliomas after first chemo-radiation therapy.