CHICAGO, IL—Radiation therapy (RT) plus combination chemotherapy prolongs both overall survival (OS) and progression-free survival (PFS) in patients with low-grade glioma compared with RT alone, long-term follow-up of the Radiation Therapy Oncology Group Study (RTOG0 9802) confirmed in a presentation at the 2014 American Society of Clinical Oncology (ASCO) Annual Meeting.
This is the first prospective study ever to demonstrate a treatment-related increase in survival in patients with grade 2, said Jan C. Buckner, MD, of the Mayo Clinic, Rochester, MN. To date, median survival is increased by 5.5 years in those who received RT plus procarbazine, lomustine, and vincristine (PCV), with 5-year and 10-year OS increased by 9% and 20%, respectively.
Previously, early results of this phase 3 study—which examined RT with or without PCV—showed that RT plus combination chemotherapy had prolonged PFS, but not OS.
The study enrolled 251 patients with supratentorial grade 2 astrocytoma, oligo-astrocytoma, or oligodendroglioma from 1998 to 2002. Low-risk patients were those younger than 40 years who had gross total resection; those considered high-risk were 40 years or older who had a subtotal resection or biopsy.
Patients were stratified by age, oligo-dominant versus astro-dominant histology, Karnofsky performance status, and presence versus absence of contrast enhancement on the preoperative imaging study, then randomized to RT alone (54 Gy in 30 fractions; n = 126) or RT followed by six cycles of chemotherapy (n = 125), Dr. Buckner said.
Median age was 40 years in the RT-alone arm and 41 years in the RT-plus-PCV arm; 61% of patients in the RT-alone arm were male and 92% were white compared with 52% and 89% in the RT-plus-PCV arm, respectively.
When the data were presented at a median follow-up of 5.9 years in the Journal of Clinical Oncology in 2012, 88 patients (35%) had died. At median follow-up of 11.9 years, 138 (55%) had died. Those in the RT-plus-PCV arm had a significantly longer median survival time, 13.3 years, compared with the RT-alone arm (7.8 years; P = 0.03; hazard ratio [HR], 0.59). Five- and 10-year OS for the RT-plus-PCV arm were 72.3% and 60.1% versus 63.1% and 40.1% for the RT-alone arm, Dr. Buckner reported.
The RT-plus-combination chemotherapy arm also had longer median PFS: 10.4 versus 4.0 years (P = 0.002; HR, 0.50). Five- and 10-year PFS for the RT-plus-PCV arm were 62.1% and 50.5% versus 44.1% and 20.9% for the RT-alone arm.