Infection study and respiration research dominate a week of health science

Infections caused an estimated 2.3 million new cancer cases worldwide in 2024, 12 per cent of the global total, according to a paper published on 28 September in The Lancet Oncology and covered by CBC News on 29 September. That is roughly one in eight cases. The count is a modelled estimate, not a registry tally. The authors matched known cancer-causing agents to global incidence databases rather than tracing individual patients.

The headline numbers are lopsided.

Helicobacter pylori, a bacterium tied to stomach cancer, accounted for 760,000 cases, mostly in eastern Asia. Human papillomavirus came close behind at nearly 750,000 cases, with high rates in sub-Saharan Africa. Hepatitis B and C together drove a significant share of liver cancers. The paper adds 16 infections to the roster of agents counted as cancer-causing. Among the additions are HIV, linked to cervical cancer, and Merkel cell polyomavirus, a rare virus associated with an aggressive skin cancer. Epstein-Barr virus was tied to about 260,000 cases globally in 2024, covering nasopharyngeal cancer, some gastric cancers and Hodgkin's lymphoma.

Sixteen new agents on the list

Gary Clifford, a cancer epidemiologist at the International Agency for Research on Cancer and a co-author, told CBC the shift reflects accumulated evidence rather than a new pathogen appearing. "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. He added that Epstein-Barr represents "quite a big burden of cancer" that was not counted in earlier estimates.

Geography still decides outcomes more than biology does. High-income countries with long-running screening and vaccination programmes carry a smaller share of the burden. Lower- and middle-resourced countries do not. In North America, H. pylori and HPV remain the most common infectious sources. In Canada, a 2019 study led by epidemiologist Karena Volesky while she was at McGill University put the share of cancers attributable to infections at four per cent.

Breathing and reaction time

A separate study out of Northwestern University, published on 29 September in the journal iScience, found that reaction times are measurably faster on an exhalation than an inhalation, by an average of 41 milliseconds. Responses during the pauses between breaths were also faster than inhalation, by 21 milliseconds.

That is a small effect. It was measured in 35 adults aged 18 to 33 who pressed a space bar when a red square turned yellow. It is also the first experiment to time responses across all phases of respiration, including the pauses. Senior author Ken Paller said the mechanism is not established: "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."

Neither study involved a wearable device, though both sit in a research area where consumer sensors are moving fast. The respiration work used an airflow sensor under the nostrils, not a watch. The cancer estimates came from epidemiological modelling.

Where AI use goes undeclared

On the professional side, a study covered by Nieman Journalism Lab on 28 September surveyed 1,138 communication scholars in 77 countries. Nearly 70 per cent had used generative AI for at least one research task, while most considered it inappropriate for most tasks. The authors describe the resulting tension as "AI shame" and call for disclosure-positive norms instead of bans.