Gliomas are a type of brain tumor that are often treated with surgery or radiation therapy. But with either therapy, gliomas almost always progress and become more aggressive. Now, new research has shown that radiation therapy followed by a certain kind of chemotherapy improved progression-free survival (PFS) and life-expectancy in adults with low-grade gliomas, when compared to only radiation therapy.
Gliomas are primary brain tumors that originate in the brain or spinal cord. They originate from the glial cells, whose main function is to support and protect the neurons in the brain. Thus, they are different from other types of cancers that originate elsewhere and spread to the brain. Gliomas are classified as low-grade and high-grade depending on their microscopic appearance. Low-grade gliomas are further classified into five types, which cause symptoms like seizures, headaches, nausea, and difficulty concentrating, due to the tumor pressing on critical portions of the brain.
Treatments include brain surgery, in which the malignant portions are removed, and radiation therapy. But since both treatments are known to be ineffective in completely eliminating the tumor, and the cancer to eventually progresses, researchers have developed a new chemo treatment. It uses procarbazine, CCNU, and vincristine (PCV), and has shown the ability to improve PFS in trials. PFS is the measure of time before and after treatment during which the condition being treated does not worsen.
"On average, patients who received PCV lived 5.5 years longer than those who received radiation alone," said Dr. Jan Buckner, deputy director of cancer practice at the Mayo Clinic Cancer Center, in a press release. "These findings build on results published in the Journal of
Clinical Oncology in 2012 which showed that PCV given with radiation therapy at the time of initial diagnosis prolongs progression free-survival but not overall survival."
PCV is one of the most commonly used chemotherapy combinations in neuro-oncology. But its effectiveness has been questioned in the past. The trial, known as ROTG 9802, tracked 251 patients with low-grade gliomas between October 1998 and June 2002, who had received chemotherapy following radiation treatment. Patients were in a high-risk category because they were all aged 40 or older, or had a less-than-complete surgical removal of their tumor when they were under 40.
The researchers also found that patients suffering from oligodendroglioma, a kind of slow-growing low-grade glioma tumors, responded better to the treatments than those with astrocytoma or oligoastrocytoma, which are two other types of low-grade gliomas. Female patients were also found to respond better to this line of treatment.
"RTOG 9802 involved a network of investigators across the United States and Canada working through the National Cancer Institute's National Clinical Trials Network," said Dr. Buckner. "This trial could only have been conducted through a publicly-funded national clinical trials network."
Such studies provide necessary breakthroughs in cancer therapy research. Cancer is estimated to be the number one killer in coming years. The American Cancer Society estimates that in the around 23,000 people will be diagnosed with primary brain tumors in 2014. Of them, 10 to 15 percent are expected to have low-grade gliomas.
Source: Buckner J, et al. At The Annual Meeting Of The American Society Of Clinical Oncology. 2014.