Conformal irradiation for pure and mixed oligodendroglioma: the experience of Centre Leon Berard Lyon

Abstract

Purpose: To assess whether conformal radiotherapy (CRT) after incomplete surgery or biopsy for pure oligodendrogliomas and mixed gliomas results in decreased long-term sequelae without impairing local control and while reducing irradiated volume.

Materials and methods: Twenty-six consecutive patients who presented with pure (21) or mixed (5) oligodendrogliomas and who were given incomplete resections were treated according 3 different strategies: CRT alone (12), chemotherapy followed by CRT (4), and chemotherapy and delayed CRT at the time of tumor progression (10). CRT consisted of multiple noncoplanar fields. Median dose was 60 Gy. Quality of CRT was assessed using tumor and normal tissue conformal indexes. The location of recurrences was assessed with MRI and dosimetric data. Late sequelae were assessed by a questionnaire exploring professional outcome, and also by a Mini Mental State Examination test.

Results: The mean overall survival was 5.2 years. Fifteen patients experienced a local relapse. All but 1 occurred in the 95% isodose. Among 11 nonevolutive patients, 6 have a full-time or part-time job.

Conclusions: Despite CRT, infield recurrence was a common feature in patients with oligodendrogliomas and mixed tumors. Further research, including molecular biology typing of tumors and type of treatment, is warranted to improve survival and quality of life.