RTOG 9802
For high-risk grade 2 glioma, does adding PCV chemotherapy after radiotherapy improve survival compared with radiotherapy alone?
Reported outcome visualization
Key results
Long-term analysis showed median OS 13.3 years with RT+PCV versus 7.8 years with RT alone (HR 0.59; P=.003); median PFS 10.4 versus 4.0 years (HR 0.50; P<.001).
Absolute Effect
Median OS difference 5.5 years; do not convert a median difference or HR into an NNT. Molecular reanalysis suggested benefit in IDH-mutant tumours, but these subgroup analyses were post hoc.
NNT: Not quantifiable or not appropriate for this design/end point.
NNH: Not quantifiable from the verified fixed-time toxicity data used in this summary; see toxicity and treatment burden below.
Time-to-event interpretation: Hazard ratios and median survival are relative/time-to-event measures; they are not converted into NNT unless a fixed-time absolute event estimate is available.
Toxicity and treatment burden
PCV adds myelosuppression, infection risk, nausea, fatigue and vincristine neuropathy; treatment completion can be difficult. A reliable trial-wide fixed-time toxicity risk difference is not used here, so NNH is not quantifiable from the verified summary.
Follow-up, limitations and maturity
Follow-up: Long-term follow-up approximately 11.9 years in the mature report.
Conducted before current WHO molecular classification; retrospective molecular subgroup analyses are hypothesis-generating. PCV toxicity and patient selection matter.
Clinical interpretation
For high-risk grade 2 glioma, adding PCV to RT yields a delayed but clinically important survival advantage; molecular diagnosis is essential when applying this legacy trial.
Primary publication and sources
Buckner JC, et al. N Engl J Med. 2016;374:1344–1355.
Current-practice context · reviewed 15 October 2026
RTOG 9802 is foundational evidence for adding PCV to RT in high-risk grade 2 glioma. Current decisions should use WHO molecular diagnosis: ASCO–SNO recommends RT plus PCV for IDH-mutant, 1p/19q-codeleted grade 2 and 3 oligodendroglioma; treatment for IDH-mutant astrocytoma also depends on grade and clinical context. PCV toxicity and patient fitness remain important.