Randomized trial of radiation therapy plus procarbazine, lomustine, and vincristine chemotherapy for supratentorial adult low-grade glioma: initial results of RTOG 9802

Abstract

Purpose: A prior Radiation Therapy Oncology Group (RTOG) clinical trial in anaplastic oligodendroglioma suggested a progression-free survival benefit for procarbazine, lomustine, and vincristine (PCV) chemotherapy in addition to radiation therapy (RT), as have smaller trials in low-grade glioma (LGG).

Patients and methods: Eligibility criteria included supratentorial WHO grade 2 LGG, age 18 to 39 years with subtotal resection/biopsy, or age ≥ 40 years with any extent resection. Patients were randomly assigned to RT alone or RT followed by six cycles of PCV. Survival was compared by using the modified Wilcoxon and log-rank tests.

Results: In all, 251 patients were accrued from 1998 to 2002. Median overall survival (OS) time and 5-year OS rates for RT versus RT + PCV were 7.5 years versus not reached and 63% versus 72%, respectively (hazard ratio [HR]; 0.72; 95% CI, 0.47 to 1.10; P = .33; log-rank P = .13). Median progression-free survival (PFS) time and 5-year PFS rates for RT versus RT + PCV were 4.4 years versus not reached and 46% versus 63%, respectively (HR, 0.6; 95% CI, 0.41 to 0.86; P = .06; log-rank P = .005). OS and PFS were similar for all patients between years 0 and 2. After 2 years, OS and PFS curves separated significantly, favoring RT + PCV. For 2-year survivors (n = 211), the probability of OS for an additional 5 years was 74% with RT + PCV versus 59% with RT alone (HR, 0.52; 95% CI, 0.30 to 0.90; log-rank P = .02).

Conclusion: PFS but not OS was improved for adult patients with LGG receiving RT + PCV versus RT alone. On post hoc analysis, for 2-year survivors, the addition of PCV to RT conferred a survival advantage, suggesting a delayed benefit for chemotherapy.

Conflict of interest statement

Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.

Figures

Fig 1.

CONSORT diagram. NA, not assessed; PCV, procarbazine, lomustine, and vincristine; RT, radiation therapy.

Fig 2.

Overall survival for all patients from date of registration/random assignment. PCV, procarbazine, lomustine, and vincristine; RT, radiation therapy.

Fig 3.

Progression-free survival for all patients from date of registration/random assignment. PCV, procarbazine, lomustine, and vincristine; RT, radiation therapy.

Fig 4.

Overall survival for patients surviving to 2 years. PCV, procarbazine, lomustine, and vincristine; RT, radiation therapy.

Fig 5.

Progression-free survival for patients surviving to 2 years. PCV, procarbazine, lomustine, and vincristine; RT, radiation therapy.