(ChemotherapyAdvisor) – Patients with newly diagnosed supratentorial adult low-grade glioma had improved progression-free survival (PFS) when procarbazine, lomustine, and vincristine (PCV) were added to radiation therapy (RT) vs RT alone and, although overall survival (OS) was not improved at study end point, beyond 2 years, the addition of chemotherapy reduced risk of disease progression by 56% and death by 48%, “suggesting a possible delayed benefit for chemotherapy,” a study reported in the Journal of Clinical Oncology online July 30.

The Radiation Therapy Oncology Group (RTOG) 9802 study randomly assigned 251 patients accrued from 1998 to 2000 to RT alone or RT followed by 6 cycles of PCV. Patients were 18 to 39 years of age with subtotal resection/biopsy, or age ≥40 years with any extent resection.

Median PFS was 4.4 years in the RT group vs not reached in the RT plus PCV arm; 5-year rates were 46% vs 63%, respectively (HR, 0.6; 95% CI, 0.41–0.86; P=0.06; log-rank P=0.005).Median OS for RT was 7.5 years vs not reached for RT plus PCV; 5-year OS rates were 63% vs 72%, respectively (HR 0.72 [95% CI, 0.47–1.10]; P=0.33; log-rank P=0.13).

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Between years 0 and 2, “OS and PFS were similar for all patients,” the investigators wrote. “After 2 years, OS and PFS curves separated significantly, favoring RT plus PCV. For 2-year survivors (n=211), the probability of OS for an additional 5 years was 74% with RT plus PCV versus 59% with RT alone (HR, 0.52; 95% CI, 0.30–0.90; log-rank P=0.02).”