The Octopaper

A follower on Twitter asked me to look at two identical papers. I agreed that they looked very similar, did some searches, and found six more. All eight papers presented the same survival curves, table values, and similar line graphs. But they were published in different journals by different authors, at different institutes, on different patients, and different cancers.

In this blog post, I present to you the Mysterious Case of the Octopaper.

My investigation started with a tweet by Nirmalya Saha, who asked me to look at two identical papers, PMID: 30305431 (Liu et al., Open Biology, 2018) and PMID: 30117667 (Cai et al., J Cell Mol Med, 2018)

Of course, I was intrigued, so I compared the two papers to each other. They were from different authors at different hospitals, published in different journals, and although both groups studied miR-125a-5p expression, they did so in different types of cancer (gastric vs lung cancer).

Two papers with very similar text…

The text of the two papers, in particular the abstracts, Methods, Results, and Discussion sections were very similar to each other, as the SimTexter analysis below showed. Blocks of text in the same color show verbatim textual similarities. Only parts of the introduction and patient description were significantly different, which is not surprising because these papers described very different types of cancers.

… and nearly identical figures

The figure similarities were also quite striking. Here are both Figures 1 compared to each other, with Cai et al. shown on the left, and Liu et al on the right. Even though two very different patient groups with very different types of cancer were studied, they showed a remarkably similar survival (panels B) and microRNA expression and methylation levels (panels D).

Here are both Figures 2. The layout is somewhat different, and the Cai paper has two extra photos, but what a remarkable similar set of results!

Figures 3 were also very similar, with some shuffling of the Western blots.

Figures 4: spot the differences.

Figures 5: again, we see the same line graphs, although now the Liu paper has been decorated with some images of mice with tumors.

Same table values, too

Tables 2 and 3 from both papers are remarkably similar as well. The risk ratios for survival of either lung or gastric cancer are …. identical – at least if we believe these tables.

But wait – there is more

If two papers are nearly identical, there might be more. I first thought that one paper might have copied/pasted data and graphs from the other paper, but the papers were submitted pretty close to each other in time. Because of our previous work on the Tadpole Paper mill, I was starting to suspect that both papers might be the products of the same paper mill, a company that sells fabricated papers in English to doctors in China who need a paper for their promotion.

So I sailed out my data detective boat onto the big internet sea to find more papers. Based on my experience, it is hard to do successful reversed image Google searches using panels from scientific papers, so I used a different strategy. I looked for the values listed in tables 2 and 3 in Google Scholar.

This approach worked. I found six more papers that had the values that the Cai and Liu papers had in common in Tables 2 and 3. A full list of the combined eight papers is given below. All papers were published between 2017 and 2020, in five different journals, by non-overlapping authors from seven different hospitals in different cities in China, about different sets of patients with different types of cancers.

Although the figure and textual similarities were not always as striking as with the first two papers, all eight papers had very similar or identical Kaplan-Meier survival curves:

Similarly, all eight papers had identical or very similar data in tables showing the univariate and multivariate “hazards models” (risk factors for long term cancer survival).

Could this have been caught during peer review?

Although the first two papers were textually pretty similar, this would have been very hard to have been caught with a plagiarism checker. One paper was in peer review but not yet accepted or published when the second paper was submitted for peer review. The other papers are textually less similar. Most importantly, each of these papers by themselves looks legit. It took a Google Scholar search for table values to detect that all eight papers are connected.

My current suspicion is that all eight papers were generated by the same paper mill company. The company might have taken data from a real paper and adapted it to a different patient set, microRNA, or cancer type. For example, the data values all appear similar to that of an older paper, from 2015 (Zhang et al. Journal of Experimental & Clinical Cancer Research (2015), DOI 10.1186/s13046-015-0176-z), which might be the original.

In most cases, they mixed in some different figures or variations, but in the Cai and Liu papers, the company might have sold a two nearly identical copies by accident to two different group of authors.

And who knows, there might be more sets of these. Let me know below in the comments if you find another one!

List of the eight papers

AuthorsTitleCitationDOIAffiliationPubPeer link
Mingzhi Cai, Qiuxian Chen, Juntao Shen, Chenbing Lv, Lisheng CaiEpigenetic silenced miR-125a-5p could be self-activated through targeting Suv39H1 in gastric cancerJ Cell Mol Med. 2018;22:4721–473110.1111/jcmm.13716Zhangzhou Affiliated Hospital of Fujian Medical University, Zhangzhou City, China
Hongxu Liu, Yegang Ma, Changhao Liu, Pengfei Li, Tao YuReduced miR-125a-5p level in non-small- cell lung cancer is associated with tumour progressionOpen Biol. (2018) 8: 18011810.1098/rsob.180118Cancer Hospital of China Medical University, Shenyang, Liaoning Province, China
Xiuli Wang, Zenghui Li, Beihua Kong, Chen Song, Jianglin Cong, Jianqing Hou, Shaoguang WangReduced m6A mRNA methylation is correlated with the progression of human cervical cancerOncotarget, 2017, Vol. 8, (No. 58), pp: 98918-9893010.18632/oncotarget.22041Qilu Hospital, Shandong University, Jinan, Shandong, China
Xiaofei Yan, Jian Zhao, Rui ZhangInterleukin-37 mediates the antitumor activity in colon cancer through β-catenin suppressionOncotarget, 2017, Vol. 8, (No. 30), pp: 49064-4907510.18632/oncotarget.17093Liaoning Cancer Hospital & Institute, Cancer Hospital of China Medical University, Shenyang, Liaoning Province
Feng Wang, Weihua Zhang, Tianfeng Wu, Heying ChuReduced interleukin-38 in non-small cell lung cancer is associated with tumour progressionOpen Biol. (2018) 8: 18013210.1098/rsob.180132The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
Jian Zhang, Tao Mao, Shuyun Wang, Dongsheng Wang, Zhaojian Niu, Zhenqing Sun, Jianli ZhangInterleukin-35 expression is associated with colon cancer progressionOncotarget, 2017, Vol. 8, (No. 42), pp: 71563-7157310.18632/oncotarget.17751The Affiliated Hospital of Qingdao University, Qingdao, China
Kuangkuang Zhu, Dong Sun, Xiaoqin Zou, Ruixia Liu, Zhen WanInterleukin-36 receptor antagonist is associated with the progression of renal cell carcinomaInternational Immunopharmacology 84 (2020) 10647410.1016/j.intimp.2020.106474Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou, Jiangsu, China
Mingfei Sun, Xianjie Zheng, Qingjiang Meng, Yanjun Dong, Guoyu Zhang, Dexin Rao, Xiaokang An, Zhongxin Yang, Lihong Pan, Shuanglin ZhangInterleukin-35 Expression in Non-Small Cell Lung Cancer is Associated with Tumor ProgressionCell Physiol Biochem 2018;51:1839-185110.1159/000495706The First Affiliated Hospital of Henan University, Kaifeng City, Henan Province, China

25 thoughts on “The Octopaper”

  1. I am a Chinese and I feel ashamed when reading this. The malformed promotion rules among doctors have been there in China for a long time, and the advertisements of paper mills can be seen everywhere in hospital universities. It is really shameful for those who are making these junk papers. Thanks a lot for your job and hope it can throw a big punch to those mills.

    Liked by 1 person

    1. As far as I know, no level of plagiarism should be accepted. (and I mean ZERO). I believe the issue is how to detect it efficiently.


      1. That is the correct answer, but it can be confusing.

        The problem is that the difference between citation, quotation and plagiarism isn’t apparent across cultural boundaries and bears better explanation than simple zero tolerance statement for plagiarism.


  2. What about the reviewers work on the manuscripts of these papers ? They also must look for plagiarism and even for autoplagiarism…..


  3. I usually don’t like too much control, but this is a terrifying example of too little quality control on the editors side. Just money making from their side.


    1. Editors (at least in most cases) are not paid to find plagiarism, though many of us can sense it from diction and inconsistencies. Plagiarism is squarely the fault of the writer. Lay the blame where it belongs.


  4. I agree with Jose Carvalho. This must be published on a scientific journal and not just restricted to
    a blog. So that the editors of various journals will do a fact check as soon as the paper is submitted to them. I myselves have peer reviewed many papers and to find this kind of trick is beyond the humanly capacity of a a reviewer. The methods/algorithms you described must be translated in a software tool to unearth such an unethical practice.


  5. This is not plagiarism, it’s much worse. It’s publishing fake results, a crime against all of humanity. Plagiarism does not distort scientific truth, but this type of activity could lead to decisions costing lives (if it was used as a basis for real-life decisions).


  6. Very important investigation done here! Nature, Science, Cell etc. should notice this. And, its risky bussiness copiers are doing, neglecting the fact that one cancer doesen’t fit all. In the end the patient may suffer because of bad science.

    Liked by 1 person

  7. I think journal should make strict provisions to have prereview check for plagiarism. It is not wise to blame reviewers. Further, there should an international active recognized platform with some legal powers to settle such cases. Otherwise such cases will be more frequent and Young Minds may be such trap.


  8. Some readers of this blog are aware that I am working together with others to get retracted a fraudulent study on the breeding biology of the Basra Reed Warbler, see for backgrounds and

    The Basra Reed Warbler is an Endangered bird species which is almost exclusively breeding in Iraq, see The fraudulent study is the first one on major aspects of its breeding biology. The study is fraudulent because the raw research data, collected in the field in Iraq, do not exist. The first author is willing to retract the study.

    It has turned out that it is extremely difficult to get published in a peer-reviewed journal an article which is mainly based on the findings of two reports about this case (both reports can be downloaded from ). The manuscript has in the meanwhile been submitted to in total 26 different peer-reviewed journals, both in the field of ornithology / ecology / nature conservation and in the field of research ethics. Only 2 journals, both in the field of research ethics, were willing to send it our for peer-review, all other submissions were desk-rejected. Several EiC’s refused to communicate about any of the findings in both reports and/or used invalid motives for their desk rejection.

    Other desk-rejections contained very valuable comments. Franz Bairlein, EiC of the Journal of Ornithology stated on 21 December 2018: ‘We agree with you that the Basra Reed-Warbler paper by Al-Sheikhly et al. is a case of scientific misconduct’. Javier Seoane, EiC of Ardeola stated on 17 March 2020: ‘The manuscript is a compelling report of a worrying case of scientific misconduct’. I am at the moment processing the extensive comments of 2 anonymous reviewers of journal #26. I will submit a new version to journal #27.

    It is thus understandable that Elisabeth Bik states in her comment: “it is not really material that would be accepted for publication in a scientific journal.”


  9. Shameful act against humanity, just for ordinary promotion to be reckoned with and not solving problems at all. I am happy that this type of blog is exposing a lot of shady deals about publication and promotion in academics. We still have a lot to learn from this. I can’t imagine this. Very sad.


  10. I noticed that all papers except one (published in “International Immunopharmacology” in 2020) were published in the period 2017-18. The fact that there is a new published version of this paper after a “silent” year could imply that the paper mill is producing a new round of falsified versions of this paper. I wouldn’t be surprised if a few more version have been submitted for review but not published yet.
    I don’t know if it would be possible (and how) to raise awareness about this problem. Maybe a published article, highlighting the main similarities between these papers could help other scientist and reviewers to identify more cases.

    Also, I assume that after the initial “success” of their business, the paper-mill most probably has produced other fake papers with multiple versions of each. It is extremely alarming.


  11. Hi. I really commend the great work. This has inspired me to crawl pubmed systematically [automatically] to identify clusters of fraudulent papers. I can’t believe this is a one-off and it would be nice to catch more of this. Thanks.


  12. This is very discouraging to all the hard-working young scientists out there. Would strongly suggest you submit this to a major general journal – write to Editors and I’m sure you get good response.


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