Suspected paper-mill articles drew more citations but fewer readers in 20 cancer journals
An international team flagged 4,085 of 33,159 articles from 2012 to 2023 as potentially linked to paper mills, according to a PNAS study. The flagged papers mostly cite and are cited by each other, and that loop inflates citation metrics at some journals.
The Scientist · Science desk

A bar showing 4,085 flagged articles out of 33,159 articles evaluated.
- Flagged articles, claim 13 4,085 of 33,159 articles 12% computed
Flagged articles The whole
| Share | Part | Whole | Percent | Claim |
|---|---|---|---|---|
| Flagged articles | 4,085 articles | 33,159 articles | 12% (computed) | 13 |
What happened
- The flagging model scores each paper's textual similarity to the titles and abstracts of retracted paper-mill articles, so a flag is a resemblance, not a confirmed finding.
- Flagged papers clustered in a subset of journals, including Journal of Experimental & Clinical Cancer Research and Molecular Cancer, while other journals were only marginally affected.
- Corresponding author Adrian Barnett of QUT said the pattern suggested widespread, coordinated manipulation of citation counts by paper mills.
Why it matters
- What it limits constraint In the clustered journals, a citation count or impact factor is weaker evidence that a cancer paper is trusted, because flagged papers feed each other's totals.
- Who's exposed exposure Anyone building a literature review or target shortlist from citation rankings in those journals can pull in flagged papers whose readership does not match their citations.
- Who has to decide decision Screening for these patterns depends on a similarity score, so acting on a paper or journal needs a human check of the flag first.
The 4,085 figure is the output of a classifier. The team's previously developed detection model compares each paper's title and abstract with those of retracted paper-mill articles, and a paper that reads similarly gets flagged [3]. That puts the flagged share at about 12.3% of the 33,159 articles [13]. The study's own title calls the distortion "Suspected" [1]. The Phys.org report does not give the model's false-positive rate, the size of the citation gap or the source of the reader counts.
The design is what makes the result worth attention. Citations come from readers, so a paper's citation count and its readership should rise together, and the nonflagged papers are the comparison group [4]. Flagged papers broke that link. "Having more citations but fewer readers makes no sense, as citations come from readers," Scancar said [9].
A second pattern fits the first. Flagged papers mostly cite and are cited by other flagged papers [5]. We'd expect papers that readers valued to draw citations from outside the flagged set as well.
The thing this doesn't tell you is who placed the citations. Adrian Barnett, the corresponding author and a statistician at QUT, said the team had documented a pattern that suggested widespread, coordinated manipulation of citation counts by paper mills [12] [7].
The impact-factor point is Barnett's, and he states it as a possibility. "Artificially high citation rates can inflate journal impact factors, amplify unreliable findings and slow scientific progress," he said [8]. The measured result is narrower. Flagged papers clustered in a subset of journals, including Journal of Experimental & Clinical Cancer Research and Molecular Cancer, while other journals were only marginally affected [6].
We think the supportable reading is journal by journal. In the clustered journals, a citation count says less about trust than it appears to. Across all 20 journals, the study does not support that claim.
Barnett's concern is downstream. "A danger is that artificially inflated citation counts may distort the evidence base by misinforming future research and clinical translation," he said [11]. The authors' proposed remedy is screening: "Our results support the screening of articles and journals for the patterns of citation manipulation we have described," Scancar said [10].
What to watch
- Whether the authors publish the detection model's false-positive rate and a journal-by-journal list of flagged shares.
- Whether Journal of Experimental & Clinical Cancer Research or Molecular Cancer respond to the clustering finding.
- Whether the same flagged-to-flagged citing loops appear outside molecular oncology.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence58
- Adoption
- Not scored
- Hype gap+15
- Incentives35
- Confidence50
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
The study, titled "Suspected distortion of citations in high-impact cancer journals", is published in Proceedings of the National Academy of Sciences.
- [2]
The team evaluated the impact of paper mills on citation patterns in 33,159 articles published in 20 journals between 2012 and 2023.
- [3]
Applying a previously developed detection model, the team flagged 4,085 articles as potentially associated with paper mills, based on their textual similarity to the titles and abstracts of retracted paper mill articles.
- [4]
Flagged papers had many more citations than nonflagged papers but had fewer readers.
- [5]
Flagged papers mostly cite and are cited by other flagged papers, measurably inflating the citation metrics of some cancer research journals.
- [6]
Flagged papers tended to cluster in a subset of journals including Journal of Experimental & Clinical Cancer Research and Molecular Cancer, whereas other journals were only marginally affected.
- [7]
Adrian Barnett said the researchers had documented a pattern that suggested widespread, coordinated manipulation of citation counts by paper mills.
- [8]
"Artificially high citation rates can inflate journal impact factors, amplify unreliable findings and slow scientific progress," Barnett said.
- [9]
"Having more citations but fewer readers makes no sense, as citations come from readers," Scancar said.
- [10]
"Our results support the screening of articles and journals for the patterns of citation manipulation we have described," Scancar said.
- [11]
"A danger is that artificially inflated citation counts may distort the evidence base by misinforming future research and clinical translation," Barnett said.
- [12]
Adrian Barnett is the corresponding author and a statistician, and a professor at QUT's Australian Centre for Health Services Innovation and School of Public Health and Social Work.
- [13]
The 4,085 flagged articles are about 12.3% of the 33,159 articles evaluated.
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Sources
1 independent publisher whose own reporting we read for this story.
- phys.orgFraudulent paper mills may be manipulating scientific citations and amplifying unreliable findings
1 article · October 16, 2026
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Topics
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