SynthesisCancer reports (Hoboken, N.J.)2026

Association Between Metformin Use and Risk of Lung Cancer in Patients With Type 2 Diabetes: A Systematic Review and Meta-Analysis.

Mehdi Karimi, Farnaz Hooshmand, Kiana Mohammadian, Seyed Morteza Ali Pourfaraji, Masoud Mortezazadeh

Abstract readSystematic ReviewMeta-Analysis
In one paragraph

Synthesis in Cancer reports (Hoboken, N.J.), 2026. The graph read 4 numbers from its abstract, feeding 1 cell of the map, but none could be read as for or against, so it casts no vote. It also reports 4 associations that do not count as treatment evidence, such as HR 0.85 (0.77 to 0.94) for lung cancer risk. Not yet cited in PubMed.

4numbers the graph read from it
0cells of the map it votes in
0citing papers in PubMed
field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

Read, but not usablea number the graph found but could not read as for or against

Lung cancer riskMetformin users vs nonusersan association or prognostic statement, not a treatment comparison · t2dfeeds one cell of the map
HR 0.850.77 to 0.94p = 0.002
RESULTS: The pooled analysis of 29 observational studies showed a significant reduction in lung cancer risk among Metformin users compared with nonusers (HR: 0.85, 95% CI: [0.77-0.94], p = 0.002).
Lung cancer riskExtended Metformin use (>  3 years) vs nonusersan association or prognostic statement, not a treatment comparison · t2dfeeds one cell of the map
HR 0.870.79 to 0.95p < 0.01
Extended Metformin use (> 3 years) was associated with a significant reduction in lung cancer risk (HR: 0.87, 95% CI: [0.79-0.95]; p < 0.01), whereas no significant effect was observed for shorter durations.
Lung cancer riskMetformin users vs nonusers, in studies conducted in Asiaan association or prognostic statement, not a treatment comparison · t2dfeeds one cell of the map
HR 0.820.68 to 0.99p = 0.04
Subgroup analyses revealed significant associations in cohort studies (HR: 0.79, 95% CI: [0.70-0.89], p < 0.01) and in studies conducted in Asia (HR: 0.82, 95% CI: [0.68-0.99], p = 0.04).
Lung cancer riskMetformin users vs nonusers, in cohort studiesan association or prognostic statement, not a treatment comparison · t2dfeeds one cell of the map
HR 0.790.70 to 0.89p < 0.01
Subgroup analyses revealed significant associations in cohort studies (HR: 0.79, 95% CI: [0.70-0.89], p < 0.01) and in studies conducted in Asia (HR: 0.82, 95% CI: [0.68-0.99], p = 0.04).

clause the extractor read what became the number

2 · Its place on the map

Where it lands on the map

Rows are treatments, columns are outcomes. The coloured squares are the cells this paper feeds, coloured by the vote it casts there. Click one to jump to what this paper adds to it.

supports the treatmentfavours the comparatorno clear differenceread, but no usable result
3 · What it changes

What it adds to each cell

For every cell the paper feeds: the belief in the claim with and without this paper, and this paper's estimate drawn against every other readable study in the cell. The ringed dot is this paper.

Metformin×adverse events & safety

No readable resultOpen on the map →What to test next →

22 readable studies in this cell: 9 favour the treatment, 8 find no difference, 5 favour the comparator.

Belief with this paper
0.27contested · 4 families support, 11 contradict · against placebo
Without itNot a counted family in this claim, so removing it changes nothing.
← favours the treatmentfavours the comparator →
0 · no effect
NCT017190031,413 enrolled · 2012
Adjusted mean -0.72-0.95 to -0.48
NCT018093271,186 enrolled · 2013
Δ -0.40-0.59 to -0.21
NCT022730501,136 enrolled · 2014
Δ -8.90-13.3 to -4.50
NCT01126580807 enrolled · 2010
Δ -0.22-0.36 to -0.08
NCT01023581784 enrolled · 2009
Δ -0.67-0.96 to -0.37
NCT00386100688 enrolled · 2006
Δ 1.47-14.8 to 20.8
NCT01217073685 enrolled · 2010
Δ 1.00-9.80 to 13.1
NCT01890122647 enrolled · 2013
Δ -0.68-0.89 to -0.47
NCT00727857600 enrolled · 2007
Δ 0.860.51 to 1.22
NCT01958671461 enrolled · 2013
Δ -2.60-13.1 to 8.10
NCT00328172302 enrolled · 2006
Δ -0.85-1.10 to -0.59
NCT01485614200 enrolled · 2012
Δ 2.40-10.0 to 14.9

This paper's own estimate is on a different scale from the rest of the cell, so it is not drawn here.

4 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

5 · Its place in the literature

Who cites it

0 citing papers in PubMed.

No citing paper in PubMed yet.

6 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

7 · Who and what money

Authors and funding

5 authors.

Mehdi KarimiFaculty of Medicine, Bogomolets National Medical University (NMU), Kyiv, Ukraine.ORCID https://orcid.org/0009-0006-4388-0214
Farnaz HooshmandFaculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran.ORCID https://orcid.org/0000-0003-4048-6626
Kiana MohammadianDivision of Hematology and Blood Banking, Department of Medical Laboratory Sciences, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran.ORCID https://orcid.org/0009-0009-3770-6166
Seyed Morteza Ali PourfarajiFaculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran.ORCID https://orcid.org/0009-0003-7712-9427
Masoud MortezazadehDepartment of Hematology-Oncology, Cancer Institute, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran.ORCID https://orcid.org/0000-0003-3585-9379

Funding

No grant is acknowledged in the PubMed record.

8 · The paper itself

Abstract

The marked sentences are the ones the graph read a number from.

BACKGROUND AND

aimLung cancer remains one of the leading causes of cancer-related mortality worldwide. Type 2 diabetes mellitus (T2DM), the most prevalent endocrine disorder, is commonly managed with Metformin, an antidiabetic medication that has demonstrated potential anticancer properties. This meta-analysis aimed to discover the association between Metformin use and the risk of lung cancer in patients with T2DM.

methodsA comprehensive search of online databases was conducted up to January 1, 2026, to identify relevant observational studies. After screening, appropriate data were extracted. Meta-analyses utilized the most fully adjusted hazard ratio (HR) with corresponding 95% confidence intervals (CI) as the effect measures. All statistical analyses were performed using R Statistical Software.

resultsThe pooled analysis of 29 observational studies showed a significant reduction in lung cancer risk among Metformin users compared with nonusers (HR: 0.85, 95% CI: [0.77-0.94], p = 0.002). Subgroup analyses revealed significant associations in cohort studies (HR: 0.79, 95% CI: [0.70-0.89], p < 0.01) and in studies conducted in Asia (HR: 0.82, 95% CI: [0.68-0.99], p = 0.04). Extended Metformin use (> 3 years) was associated with a significant reduction in lung cancer risk (HR: 0.87, 95% CI: [0.79-0.95]; p < 0.01), whereas no significant effect was observed for shorter durations.

conclusionThis meta-analysis indicated a potential protective effect of Metformin use in individuals with T2DM against lung cancer, with a significant risk reduction observed, particularly among long-term users and in Asian populations. The significant associations identified in cohort studies and in extended-duration use underscore metformin's promise in lung cancer prevention.

Indexed as

Diabetes Mellitus, Type 2Hypoglycemic AgentsLung NeoplasmsMetforminHumansObservational Studies as TopicRisk AssessmentRisk FactorsHypoglycemic AgentsMetformindiabetesepidemiologylung Cancermeta‐analysismetforminrisk

Identifiers

PMID42581008
PMCPMC13461527

What Socratic holds

Texttitle and abstract
LicenceCC BY
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the Socratic graph.