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Journal Club

Tumor/Skull Base

Influence of Supramarginal Resection on Survival Outcomes after Gross Total Resection in IDH-Wildtype Glioblastoma

Journal of Neurosurgery | 2022

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

10.3171/2020.10.JNS203366

PMID

N/A

PICO

Population

Adults with newly diagnosed IDH-wildtype glioblastoma who achieved gross-total resection of contrast-enhancing tumor and completed standard adjuvant therapy in a 3-campus Mayo cohort.

Intervention

Supramarginal resection of FLAIR-hyperintense tissue beyond the contrast-enhancing tumor.

Comparator

Lower or no supramarginal resection after gross-total resection of contrast-enhancing tumor.

Outcomes

Overall survival, progression-free survival, and threshold effects of increasing supramarginal resection percentage.

Design

Type

Multicenter observational cohort study

Randomized

No

Multicenter

Yes

Blinded

N/A

Follow-up

Overall survival censored at most recent clinical follow-up

Primary endpoint

Overall survival after gross-total resection of contrast-enhancing tumor.

Secondary endpoints

  • Progression-free survival
  • Threshold analyses of supramarginal resection percentage
  • Associations with age, KPS, MGMT status, and ventricle contact

Practice impact

What this means

This study argues that going beyond the enhancing margin may help in selected IDH-wildtype glioblastoma cases, but it is still retrospective evidence. The practical lesson is to consider safe supramarginal resection when anatomy allows, not to chase a fixed percentage at the expense of neurologic function.

Bottom line

The paper supports aiming for safe supramarginal resection in selected IDH-wildtype glioblastoma cases, but it does not justify pushing beyond functional limits to hit a numeric threshold.

Strength of evidence

low

Recommendation

consider change

Why it matters

  • The survival signal is clinically interesting and directionally consistent with other supramarginal-resection literature.
  • The study is retrospective and highly selected, so causality remains uncertain.
  • Threshold cutoffs like 20% are best treated as planning heuristics, not surgical commandments.

What would change my mind

  • A prospective or randomized study showing no survival gain after adjusting carefully for anatomy and functional risk.
  • Evidence that attempted supramarginal resection increases durable neurologic harm enough to offset the survival signal.

Critical appraisal

How strong is the paper?

Methods critique

Risk of bias

This was a retrospective observational cohort drawn from 888 screened patients, with only 101 meeting the strict final criteria, so selection bias is unavoidable.

Confounding

More aggressive FLAIR resection may track with tumor location, resectability, surgeon preference, and functional risk in ways that multivariable adjustment cannot fully remove.

Missing data

Only patients with complete molecular, imaging, and adjuvant treatment data were included, which improves consistency but may bias the cohort toward fitter, more fully characterized patients.

Multiplicity

The paper tested multiple survival covariates and exploratory supramarginal resection thresholds, so threshold findings should be viewed as hypothesis-generating rather than definitive cut points.

Notes

  • The cohort was restricted to IDH-wildtype tumors with gross-total contrast-enhancing resection.
  • Volumetric MRI measurements were central to the exposure definition.
  • The authors themselves note the limits of retrospective threshold finding.

Stats check

NNT

N/A

Effect sizes

  • Increasing supramarginal resection percentage was associated with longer overall survival: HR 0.99 (95% CI 0.98-0.99; p=0.02).
  • A 20% supramarginal resection threshold was associated with better overall survival: HR 0.56 (95% CI 0.35-0.89; p=0.01).
  • Greater than 60% supramarginal resection had no significant survival effect: HR 0.74 (95% CI 0.45-1.21; p=0.234).

Absolute effects

  • Mean survival was 19.1 months with more than 20% supramarginal resection versus 16.8 months with less than 20%.
  • Mean survival was 20.1 months with more than 50% supramarginal resection versus 18.3 months with less than 50%.
  • Among 888 reviewed patients, only 101 met the final study criteria.

Concerns

  • The hazard ratio per percentage point is statistically significant but modest in magnitude.
  • Threshold analyses are especially vulnerable to overfitting in retrospective datasets.
  • The exposure is strongly tied to anatomy and surgical judgment, which limits causal inference.

External validity

Who it applies to

Selected adults with newly diagnosed IDH-wildtype glioblastoma in whom gross-total contrast-enhancing resection is achievable and additional FLAIR resection can be attempted safely.

Who it does not

Patients with eloquent or deep tumors where extra FLAIR resection would create unacceptable neurologic risk, or tumors without measurable resectable FLAIR beyond the enhancing margin.

Generalizability notes

  • Applicability is strongest in centers with high-quality volumetric MRI assessment and experienced glioma surgery teams.
  • The findings are about selected patients after gross-total contrast-enhancing resection, not all glioblastoma cases.
  • The threshold percentages should not be treated as rigid universal targets.

Evidence trace

Source trace and metadata

Citations (4)

claim_id

methods_critique.risk_of_bias

locator

p. 1

claim_id

stats_check.effect_sizes

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p. 1

claim_id

stats_check.absolute_effects

locator

p. 15 Figure 3

claim_id

practice_impact.bottom_line

locator

p. 2

Metadata

Generated at

2026-03-08T15:40:00-05:00

Version

manual-pdf-repair-v1