SynthesisInternational journal of colorectal disease2020

Metformin and colorectal cancer: a systematic review, meta-analysis and meta-regression.

Cheng-Ann Winston Ng, Amy Aimei Jiang, Emma Min Shuen Toh, Cheng Han Ng, Zhi Hao Ong, Siyu Peng, Hui Yu Tham, Raghav Sundar, Choon Seng Chong, Chin Meng Khoo

Abstract readMeta-AnalysisSystematic Review
PubMed Publisher
In one paragraph

Synthesis in International journal of colorectal disease, 2020. The graph read 3 numbers from its abstract, feeding 1 cell of the map, but none could be read as for or against, so it casts no vote. Cited by 71 papers, 6 of them syntheses that pooled it.

3numbers the graph read from it
0cells of the map it votes in
71citing papers in PubMed, 6 pooled it
6.3field-weighted citation impact, top 2% of its field
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

All-cause mortalitycomparator not stated · t2dfeeds one cell of the map
HR 0.600.53 to 0.67p < 0.001
Overall survival (HR 0.6, CI 0.53-0.67, p < 0.001) and CRC-specific survival (HR 0.66, CI 0.59-0.74, p < 0.001) were higher among metformin users compared with non-metformin users.
All-cause mortalitycomparator not stated · t2dfeeds one cell of the map
HR 0.660.59 to 0.74p < 0.001
Overall survival (HR 0.6, CI 0.53-0.67, p < 0.001) and CRC-specific survival (HR 0.66, CI 0.59-0.74, p < 0.001) were higher among metformin users compared with non-metformin users.
All-cause mortalitycomparator not stated · t2dfeeds one cell of the map
HR 0.770.68 to 0.87p < 0.001
Further analysis on overall survival of metastatic CRC patients revealed significantly higher survival rates in metformin users (HR 0.77, CI 0.68-0.87, p < 0.001).

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×all-cause mortality

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

1 readable study in this cell: 0 favour the treatment, 1 find no difference, 0 favour the comparator.

Belief with this paper
0.25no deciding trial · 0 families support, 0 contradict · against placebo
Without itNot a counted family in this claim, so removing it changes nothing.
← favours the treatmentfavours the comparator →
1 · no effect
NCT000387272,779 enrolled · 1996
HR 0.990.79 to 1.25

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

71 citing papers in PubMed, 6 syntheses or guidelines pooled it, 124 citations in OpenAlex.

  1. Pooled it
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  3. Pooled it
  4. Pooled it
  5. Pooled it
  6. Pooled it
  7. Trial
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  14. AΙ-Driven Drug Repurposing: Applications and Challenges.Medicines (Basel, Switzerland) · 2025
    Review
  15. Article
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  17. Review
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  19. Article
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11 more citing papers are in PubMed but not listed here.

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

10 authors at 3 institutions in 1 country.

Cheng-Ann Winston NgYong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore, 117597, Singapore.
Amy Aimei JiangYong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore, 117597, Singapore.
Emma Min Shuen TohYong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore, 117597, Singapore.
Cheng Han NgYong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore, 117597, Singapore.
Zhi Hao OngYong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore, 117597, Singapore.
Siyu PengDepartment of Haematology-Oncology, National University Cancer Institute, NUH Medical Centre, Singapore, 119074, Singapore.
Hui Yu ThamDivision of Colorectal Surgery, University Surgical Cluster, National University Hospital, 5 Lower Kent Ridge Rd, Singapore, 119074, Singapore.
Raghav SundarYong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore, 117597, Singapore.
Choon Seng ChongYong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore, 117597, Singapore.
Chin Meng KhooYong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore, 117597, Singapore. mdckcm@nus.edu.sg.ORCID http://orcid.org/0000-0003-1601-2391
National University of Singapore · SGNational University Cancer Institute, Singapore · SGNational University Hospital · SG

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.

purposeMetformin may have a role in reducing the incidence of colorectal cancer (CRC) and improving survival outcome. This meta-analysis explored the effect of metformin use on colorectal adenoma and cancer incidence, and colorectal oncological outcomes.

methodsA database search was conducted on Medline, Embase and CNKI for studies comparing metformin vs. non-metformin users, metformin users vs. non-diabetics and metformin users vs. diabetics with diet-only treatment. Meta-analysis was done with DerSimonian and Laird with risk ratios (RR), and hazard ratios (HR) for survival outcomes.

resultsWe included 58 studies and summarized incidences of colorectal adenoma and cancer, as well as cancer survival outcomes. Metformin users had a significant lower incidence of colorectal adenoma (RR 0.77, CI 0.67-0.88, p < 0.001), advanced adenoma (0.61, CI 0.42-0.88, p = 0.008) and CRC (RR 0.76, CI 0.69-0.84, p < 0.001) respectively compared with non-metformin users. Overall survival (HR 0.6, CI 0.53-0.67, p < 0.001) and CRC-specific survival (HR 0.66, CI 0.59-0.74, p < 0.001) were higher among metformin users compared with non-metformin users. Further analysis on overall survival of metastatic CRC patients revealed significantly higher survival rates in metformin users (HR 0.77, CI 0.68-0.87, p < 0.001).

conclusionThis meta-analysis showed that metformin use significantly reduces colorectal adenoma and cancer incidence and improves colorectal cancer outcomes.

Indexed as

AdenomaColorectal NeoplasmsDiabetes Mellitus, Type 2MetforminHumansHypoglycemic AgentsHypoglycemic AgentsMetforminAdenomaIncidenceMalignantSurvival outcomesType 2 diabetes mellitus

Identifiers

PMID32592092
OpenAlexW3037920944

What OpenQuestion holds

Texttitle and abstract
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 OpenQuestion graph.