Gene in Brain Tumor Increases Response to Radiation Therapy Combined with Chemo

Combining radiation therapy with chemotherapy almost doubled the median survival time for patients with a form of brain tumor called an oligodendroglioma that has a chromosomal abnormality called an 1p19q deletion.

The National Institutes of Health (NIH) sponsored a study that involved 286 patients with this aggressive form of brain tumor. Oligodendrogliomas  are known for invading the nerve tissue in the brain, according to a press release from the National Cancer Institute (NCI) that can be found at http://www.cancer.gov/newscenter/pressreleases/2012/OligodendrogliomaRTOG. This type of brain tumor primarily presents in adults, with an average age of 35 at diagnosis.

“The presence of the chromosomal abnormality was associated with substantially better prognosis and marked improvements in survival in a treatment program of combined chemotherapy and radiation therapy compared to radiation therapy alone,” stated the NCI.

Participants in the trial were randomly assigned to receive radiation therapy alone, or radiation combined with PCV (procarbazine, lomustine and vincristine) chemotherapy. The researchers then collected and stored tumor tissue from all the patients, followed by an analysis of half the tumor specimens after 11 years.

Although the median overall survival time was similar in both study groups, the 126 patients with tumors that carried the 1p19q co-deletion who received radiation therapy plus PCV experienced a median survival of 8.7 years, compared to 2.7 years for those who only received radiation therapy. Even more impressive was a finding that 59 patients who received the dual treatment and had tumors with the co-deletion had a median survival time of 14.7 years, compared to 7.3 years  for 67 patients with the same tumor type who received only radiation.

“This observation suggests that patients whose tumors contain the chromosomal abnormality will live substantially longer than patients whose tumors don’t carry it, regardless of treatment,” stated the press release.

Chemotherapy did not aid survival among the patients with tumors without the chromosomal abnormality.

The study can be accessed under Radiation Therapy Oncology Group (RTOG) 9402. Additional participants in the trial included the North Central Cancer Treatment Group, the National Cancer Institute of Canada Clinical Trials Group, the Eastern Cooperative Oncology Group and SWOG (formerly the Southwest Oncology Group).

“The Radiation Therapy Oncology Group and other participating cooperative groups are to be congratulated for conducting this randomized clinical trial on a rare form of brain tumor that took many years,” said Jeffrey Abrams, M.D., associate director, Cancer Therapy Evaluation Program, NCI. “Their persistence and dedication was rewarded as this genetic abnormality has a powerful effect on survival, and the results will change how patients with this disease are treated.”