A Medical Journal Retracts a 2022 Study That Linked Vaping to Cancer
The World Journal of Oncology recently retracted a February 2022 article claiming that nicotine vapers face about the same cancer risk as cigarette smokers. “After publication of this article,” the editors explain, “concerns have been raised regarding the article’s methodology, source data processing including statistical analysis, and reliability of conclusions.” Because “the authors failed to provide justified explanations and evidence for the inquires [sic], subsequently this article has been retracted at the request of Editor-in-Chief.”
Some of the concerns raised by this article are similar to the problems with other studies that have linked vaping to smoking-related diseases. Most conspicuously, this study failed to address the question of whether diagnoses were made before or after people started vaping, a minimum requirement for inferring causation. In 2020, the same problem led to the retraction of a Journal of the American Heart Association article that reported an association between vaping and heart attacks.
The World Journal of Oncology article—which was attributed to no fewer than 13 researchers at institutions such as the University of Missouri, Temple University Hospital, the Mayo Clinic, and the Icahn School of Medicine at Mount Sinai—has other obvious problems that should have been apparent before publication. It features enough inconsistencies, writing errors, non sequiturs, and failures of reasoning to make you wonder whether peer reviewers and editors actually read it, let alone carefully evaluated its strengths and weaknesses.
As critics have noted, the publication of such studies suggests that the peer review process is biased against vaping, favoring articles that highlight its potential hazards even when the science underlying them is weak. In an email, Brad Rodu, a University of Louisville professor of medicine who has been studying tobacco harm reduction for decades, says the “grossly flawed” study of vaping and cancer raises a troubling question: “How could it get through peer review?”
In the retracted study, University of Illinois internist Anusha Chidharla and her 12 co-authors analyzed data from the National Health and Nutrition Examination Survey. The sample included 154,856 respondents surveyed from 2015 through 2018, of whom 5 percent reported that they had ever used e-cigarettes, 31.4 percent said they were current smokers, and 63.6 percent said they did not smoke and had never used e-cigarettes. The survey also asked whether participants had ever been diagnosed with cancer.
Crucially, the study does not include information on when the e-cigarette users began vaping. But the authors note that “e-cigarettes [were] used as a strategy to quit smoking in most cancer respondents,” which suggests that their diagnoses generally preceded their e-cigarette use. If so, that would be consistent with what Rodu and University of Louisville research economist Nantaporn Plurphanswat found when they analyzed data on other smoking-related diseases from the Population Assessment of Tobacco and Health Survey, which includes information on the timing of both diagnoses and e-cigarette use.
Chidharla et al. classified participants as “e-cigarette users” if they had ever vaped and were not current smokers. The researchers did not take into account whether the respondents in that group had a history of smoking, which is obviously problematic when you are trying to distinguish between correlation and causation.
“The authors reclassified former smokers as nonsmokers, thereby obscuring the effects of ‘former,'” Rodu notes. “That also raised the cancers in their reference group, which was inappropriate.”
Keeping those points in mind, what did the researchers find? They seemed confused about that.
According to the abstract, “the e-cigarette users [had] lower prevalence of cancer compared to traditional smoking (2.3% vs. 16.8%; P < 0.0001)." That is consistent with the numbers reported in Table 2. But ac
Article from Reason.com