Infection study puts 2.3 million cancers on pathogens, with H. pylori and HPV leading

Infections caused an estimated 2.3 million new cancer cases worldwide in 2024, or 12 per cent of all new diagnoses, according to a study published on Monday in The Lancet Oncology. Researchers at the International Agency for Research on Cancer (IARC), an arm of the World Health Organization, led the work, CBC News reported on 29 September.

The bacterium Helicobacter pylori accounted for the largest share: 760,000 cases, mostly in eastern Asia, where it raises the risk of stomach cancer. Human papillomavirus (HPV) followed with nearly 750,000 cases globally, with high rates in sub-Saharan Africa. HPV causes 100 per cent of cervical cancer cases, and is also linked to anal, vulvar, vaginal, penile and some head and neck cancers. Hepatitis B and hepatitis C were tied to a significant number of liver cancer cases.

Sixteen more cancers added to the list

For the first time, the researchers linked even more cancers to infections, expanding their list to include 16 additional ones. Gary Clifford, a cancer epidemiologist and study co-author based in Lyon, France, said the evidence base has grown. "There's been new infectious agents identified in this time as being cancer-causing, and even the infectious agents that we knew about in the past, the evidence has increased about the number of different cancers that they can cause," he said, according to CBC News.

Among the additions: HIV and its link to cervical cancer, and Merkel cell polyomavirus, a very rare virus that can lead to an aggressive form of skin cancer. The biggest shift in the numbers is Epstein-Barr virus (EBV), which was linked to about 260,000 cases in 2024 and can lead to nasopharyngeal cancer, some gastric cancers and Hodgkin's lymphoma. "That's quite a big burden of cancer caused by Epstein-Barr virus that was not counted in the past, but is now recognized," Clifford said.

EBV is also a key risk factor in developing multiple sclerosis. Unlike some of the other infections in the study, there are no vaccines or antibiotic treatments to fight it. "The fact that we're seeing Epstein-Barr has caused all these chronic diseases, it's increasingly becoming a target that people need to focus on for prevention," Clifford said.

Wide regional gaps, and a much smaller Canadian share

The global report highlights vast regional differences, mostly driven by historical disparities, the researchers said. High-income countries that established cancer screening and vaccination programs over the last few decades are doing much better than lower- and medium-resourced countries where access to prevention and treatment is limited. "We really still have a lot of work to do implementing things that we know work and we've known for a long time but haven't really made it into all populations in the world," Clifford said.

In North America the burden of cancer-causing infections is much lower, but H. pylori and HPV remain the most common sources. In Canada, a 2019 study estimated the rate of cancers attributable to infections at four per cent. Karena Volesky, an epidemiologist in Montreal, led that Canadian research team while at McGill University. "It tells us how important each of the 12 infections are," Volesky said of the new global numbers.

Method matters here. To reach the estimate, the IARC team first examined which infections cause cancer, then calculated what fraction of those cancers can be linked to specific infections, and applied those calculations to global databases of new cancer cases. It is an estimate built on modeling, not a count of individual diagnoses.

A 41 millisecond gap between inhaling and exhaling

The same week brought a much smaller finding, this one about breathing. Neuroscientists at Northwestern University found that response speed on an exhalation is faster than on an inhalation by an average of 41 milliseconds, or 1/25th of a second. Response speed during the pauses between breaths is also faster than inhalation, by 21 milliseconds. The study, "Response speed is modulated by respiratory phase," was published on 29 September by Cell Press in the journal iScience, according to Northwestern's news office.

It is the first experiment to measure response speed during all phases of respiration, including the pauses between breaths. Senior author Ken Paller is the James Padilla Professor of Psychology at Northwestern; the lead author is neuroscientist Erika M. Yamazaki, a former member of Paller's lab who has continued to partner on research since earning her Ph.D. Thirty-five adults aged 18 to 33 completed a Psychomotor Vigilance Task, pressing the space bar as quickly as possible when a red square turned yellow, while wearing a device under the nostrils to measure airflow. Each participant did the task twice, once before and once after a nap or an eight-hour sleep in the lab.

"By using a tangible and easy to understand task, we were able to show the relationship between respiration and cognition, which I hope people in a range of fields will find application for," Yamazaki said. "Study of the brain and body connection is still a new field of research, which makes the study findings all the more exciting."

Paller was careful about the mechanism. "This study documents an important link between respiration and the brain systems for responding to environmental events," he said. "We don't yet know exactly how they are linked, but we suspect neurophysiological efficiency, because other studies have shown that various brain oscillations are synchronized with the rhythms of one's breathing." Paller's lab is currently working on related research funded by the National Institutes of Health and led by Yamazaki, focused on sleep apnea, a problem that is often under-diagnosed.

AI shame in research, and a $2,999 study app

On the tooling side, Nieman Journalism Lab reported on 28 September on a study of how communication scholars actually use generative AI. Researchers from National Yang Ming Chiao Tung University in Taiwan, the University of Amsterdam and Utrecht University surveyed more than 1,100 scholars from 77 countries and held four focus group discussions, publishing the results in Information, Communication and Society.

Nearly 70 per cent of respondents had already used generative AI in at least one research-related task, but most also considered AI use inappropriate for most research tasks. Just over half said using AI for writing texts (55 per cent) and generating code (50.4 per cent) were appropriate. The authors describe a "transparency paradox": researchers may feel an ethical obligation to disclose AI assistance while fearing that disclosure makes their work look less credible, a tension the study calls "AI shame." They recommend a "disclosure-positive" culture in which journals require researchers to state the stages at which they used generative AI. "Simply forbidding the use of genAI, or pretending that it is not being used, is neither sustainable nor constructive," the authors write.

Not every item in the dossier is a study. A listing on the side-project marketplace SideProjectors, posted on 29 September and updated the same day, offers Studlark, a full-stack AI study SaaS with private study rooms, friend-to-friend messaging, group chat and an on-demand AI assistant, for $2,999, described as negotiable. The listing says the sale includes full source code, a GitHub repository transfer, SQL and database migrations, an .env.example file, a SUPABASE-SETUP.txt file, setup documentation and seven days of email setup support. It explicitly excludes the seller's Supabase project, .env files and API keys. Buyers would still need to create their own Supabase project, run the migrations, add their own AI credentials, deploy the application, connect a payment provider and add production terms and privacy pages.

Two of this week's items point in the same direction: the pathogens behind a large slice of the world's cancer burden are known and, in several cases, preventable, while the tools researchers use to study them remain contested. The IARC paper's estimate is the headline number, but its practical weight sits in the regional gap it describes, and in the viruses like EBV for which no vaccine or treatment yet exists.