A team of researchers working at the Mayo Clinic in Rochester, MN has made a discovery that may prolong the lives of cancer patients with certain types of slow-growing brain tumors. According to a report from UPI, the study tracked a sample of patients treated for grade 2 gliomas beginning in 1998.

The study showed that adding chemotherapy to the typical radiation treatment kept tumors originating from the glial cells from growing and spreading. The findings were consistent with or without surgery.

According to lead author Dr. Jan Buckner, the chair of oncology at the Mayo Clinic, “Until now, there hasn’t been any therapy known to improve life expectancy for these patients.”

Grade 2 gliomas make up a small percentage of the 23,000 brain cancer cases documented in 2015, but a specific treatment for the tumors evaded researchers for quite some time. The study’s findings suggest that adding chemotherapy to standard brain cancer treatments can prolong the lives of patients suffering from grade 2 gliomas.

Grade 2 gliomas disproportionately affect young adults, who often die prematurely. Half of the 251 participants in the study were assigned to six weeks of radiation therapy, and the other half received an additional trio of chemotherapy drugs including procarbazine, CCNU and vincristine. The average age of a patient in the study was 40 years old.

55 percent of the sample group died by the end of the study period, but the results showed that people who received chemotherapy survived for an average of 13 years, as opposed to the average of eight years for the group that only received radiation.

There have been significant advances in available chemotherapy drugs since the study began, and it remains unclear whether the same effect would be seen with more modern drugs. The researchers acknowledge that there are a wide range of other factors that could influence survival odds in brain cancer patients, and hope to continue to study the effects of chemotherapy on the success of more traditional treatments.

A press release describing the details of the study can be found here.