← Antiplatelet & anticoagulant × adverse events & safety

TrialJNCI cancer spectrum2023

Association of metformin, aspirin, and cancer incidence with mortality risk in adults with diabetes.

Suzanne G Orchard et al.PubMed ↗Full text ↗Publisher ↗

  • Aspirinlooks bad hereMore cancer deaths, no clear effect on cancer cases.Weak evidence: one subgroup, may be chance.
  • Metforminlooks good hereFewer cancer cases, no clear link with cancer deaths.Correlation only, not a test of it.

What the trial testedrandomised · 2,045 people · 2023

One subgroup · may be chance

May have increased cancer deaths in metformin users

2.5×1.2× to 5.4×

aspirin vs placebo, in metformin users

Bigger than 8 in 10 for adverse events & safety

As reported

HR 2.53, 95% CI 1.18–5.43 · the paper's word: cancer mortality

Range includes no effect

No clear effect on cancer cases

+11%−25% to +64%

aspirin vs placebo, in metformin users

Bigger than 3 in 10 for adverse events & safety

As reported

HR 1.11, 95% CI 0.75–1.64 · the paper's word: cancer incidence

What moved togetherboth groups pooled, not the treatment’s effect

Correlation, not cause

Metformin went with fewer cancer cases

−32%−49% to −10%

metformin vs no metformin

Bigger than 6 in 10 for adverse events & safety

As reported

HR 0.68, 95% CI 0.51–0.90 · the paper's word: cancer incidence

Correlation · may be no link

No clear link with cancer deaths

−28%−57% to +19%

metformin vs no metformin

Bigger than 6 in 10 for adverse events & safety

As reported

HR 0.72, 95% CI 0.43–1.19 · the paper's word: cancer mortality

Who was studied, and how

19,114people in the Aspirin in Reducing Events in the Elderly trial, from 2010
2,045of them with type 2 diabetes, aged 70+, in this paper

Already taking metformin, or nottheir own situation, not assigned

965metformin users
1,080not on metformin

Metformin went with fewer cancer cases−32%

No clear link with cancer deaths−28%

correlation, not a test

Among the 965, the trial had randomly assignedassigned by chance

aspirin
placebo

May have increased cancer deaths2.5×

No clear effect on cancer cases+11%

randomised · one subgroup, may be chance

the abstract, start to end

… risk (adjusted hazard ratio [HR] = 0.68, 95% confidence interval [CI] = 0.51 to 0.90), but no conclusive benefit for cancer mortality (adjusted HR = 0.72, 95% CI = 0.43 to 1.19).

… mortality compared with placebo (HR = 2.53, 95% CI = 1.18 to 5.43), but no effect was seen for cancer incidence (HR = 1.11, 95% CI = 0.75 to 1.64).

← favours treatmentfavours comparator →
could be chance
Cancer incidencemetformin vs no metformin
HR 0.680.51–0.90
Cancer mortalitymetformin vs no metformin
HR 0.720.43–1.19
Cancer mortalityaspirin vs placebo, in metformin users
HR 2.531.18–5.43
Cancer incidenceaspirin vs placebo, in metformin users
HR 1.110.75–1.64
MetforminAntiplatelet & anticoagulantAdverse events & safety

Antiplatelet & anticoagulant × adverse events & safetyharms?no deciding trial

unlikelylikely
0.25only evidence
1 / 6

11 papers cite it

2023
2024
2025
this paperpooled itcites it

The trial

NCT0103858319,114 enrolled2010
Full record →Abstract, authors, funding and every citing paper · PMID 36857596