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Journal Club

Tumor/Skull Base

Glioma Groups Based on 1p/19q, IDH, and TERT Promoter Mutations in Tumors.

N Engl J Med | 2015

Rapid review note

Journal Club is a rapid, AI-assisted appraisal layer. It highlights study design, effect estimates, and practice relevance, but it is still a briefing, not a replacement for the paper.

For education only. Not medical advice.

Paper snapshot

Rapid study overview

Open paper

DOI

10.1056/NEJMoa1407279

PMID

26061753

PICO

Population

Patients with infiltrative gliomas (n=1087).

Intervention

Molecular classification based on TERT promoter mutations, IDH mutations, and 1p/19q codeletion.

Comparator

Comparison of clinical and molecular characteristics across the five defined molecular groups.

Outcomes

Group prevalence, age at diagnosis, overall survival, and association with germline variants.

Design

Type

Observational cohort study

Randomized

No

Multicenter

Yes

Blinded

Not applicable: biomarker analysis and retrospective clinical correlation.

Follow-up

Not explicitly stated; survival analysis uses available clinical data.

Primary endpoint

Definition and characterization of five molecular glioma groups.

Secondary endpoints

  • Association of groups with overall survival in grade II/III gliomas
  • Association of groups with germline variants
  • Distribution of groups by tumor grade

Practice impact

What this means

This landmark 2015 study defined five molecular groups of adult diffuse gliomas based on IDH, TERT promoter, and 1p/19q status. The groups have distinct ages at onset and prognoses, with the triple-positive group (IDH-mut, TERT-mut, 1p/19q codeleted) having the best survival in lower-grade gliomas. This work directly informed the 2016 WHO classification, making molecular testing standard for glioma diagnosis.

Bottom line

This study provides the molecular evidence base for the five-group classification of adult diffuse gliomas now used in WHO diagnostics.

Strength of evidence

high

Recommendation

change practice

Why it matters

  • Large cohort with robust biomarker data.
  • Groups show distinct clinical profiles and survival.
  • Already integrated into WHO CNS tumor classification.

What would change my mind

  • Prospective validation showing the groups do not predict response to specific therapies.
  • Evidence that simpler or alternative markers provide superior prognostic stratification.

Critical appraisal

How strong is the paper?

Methods critique

Risk of bias

Low for biomarker definition; retrospective clinical correlation introduces potential for confounding by treatment and era.

Confounding

Age and treatment are major potential confounders for survival associations; multivariable analysis adjusts for age, grade, and treatment type.

Missing data

Not explicitly discussed for key variables; all 1087 tumors had molecular data scored.

Multiplicity

Multiple comparisons across groups for clinical and molecular features; no explicit correction stated.

Notes

  • Large, well-characterized cohort from major centers.
  • Classification is descriptive and associative, not interventional.

Stats check

NNT

Not applicable: classification study without therapeutic intervention.

Effect sizes

  • HR for overall survival in grade II/III gliomas: triple-positive vs. triple-negative HR 0.31 (95% CI 0.14-0.69)
  • Prevalence: 29% of grade II/III gliomas were triple-positive (IDH-mut, TERT-mut, 1p/19q codeleted).

Absolute effects

  • Mean age at diagnosis: 37 years for IDH-mutant only group; 59 years for TERT-mutant only group.
  • Sample size: 1087 gliomas analyzed.

Concerns

  • Survival analysis for grade IV gliomas showed no independent association with molecular groups.
  • Cohort assembled retrospectively; treatment heterogeneity not fully controlled.

External validity

Who it applies to

Adult patients with infiltrative gliomas in centers performing molecular testing.

Who it does not

Pediatric gliomas, non-infiltrative gliomas (e.g., pilocytic astrocytoma), or centers without access to molecular profiling.

Generalizability notes

  • Findings underpin the 2016 WHO classification update.
  • Cohort from US academic centers; applicability to diverse populations is untested.

Evidence trace

Source trace and metadata

Citations (3)

claim_id

methods_critique.confounding

locator

p. 2503 Results

quote

In multivariable models... we adjusted for age, grade, and treatment type.

claim_id

stats_check.effect_sizes

locator

Table 2

quote

Hazard ratio for death... triple-positive vs. triple-negative 0.31 (95% CI 0.14-0.69)

claim_id

practice_impact.bottom_line

locator

p. 2507 Discussion

quote

Our findings provide a framework for molecular classification that has been incorporated into the updated WHO classification.

Metadata

Generated at

2026-03-06T13:41:29.251Z

Version

top 100 cited in past 20 years