Pilot evaluation of 1p and 19q deletions in anaplastic oligodendrogliomas collected by a National Cooperative Cancer Treatment Group

Radiation Therapy Oncology Group (RTOG) trial 94-02 is designed to compare the effectiveness of radiation therapy alone with radiation therapy plus procarbazine, lomustine, and vincristine (PCV) chemotherapy in patients with anaplastic oligodendrogliomas and mixed oligoastrocytomas. This prospectively collected, randomly treated, prospectively followed cohort is the ideal set of patients to validate the observation that anaplastic oligodendrogliomas with 1p and 19q deletions have a prolonged survival and a better response to chemotherapy. For patients entered on RTOG 94-02, fresh blood specimens, as well as slides and paraffin blocks, have been obtained (with informed consent) on enrollment. Peripheral blood leukocytes (buffy coats) have been frozen and stored and Epstein-Barr-virus-immortalized lymphoblastoid lines have been prepared from the blood specimens. In this report, the authors describe a pilot 1p/19q deletion analysis of 26 tumors from RTOG trial 94-02. In this analysis, it is shown that 1p/19q deletion analysis by fluorescence in situ hybridization is feasible on blocks collected from this trial. Also demonstrated is that the incidence of 1p and 19q deletions in this pilot series of anaplastic oligodendrogliomas and mixed oligoastrocytomas is similar to that reported in previous studies. When the clinical follow-up on this prospective trial is mature and the deletion studies have been completed, the authors should be able to determine whether 1p and 19q deletions predict a prolonged survival and/or responsiveness to PCV chemotherapy plus radiation in patients with anaplastic oligodendrogliomas and mixed oligoastrocytomas.