• smoking
• alcohol use
• diet
• metabolic diseases such as obesity and type 2 diabetes
• chronic health conditions

The researchers followed participants for more than a decade, using national and regional cancer registries up to 2020–2021 to track who went on to develop cancer.

What did China's data show?

In Shanghai, lifestyle and health factors drove almost the entire cancer gap. After accounting for the 11 measured factors, only about 15% of the disparity between men and women remained unexplained.

Smoking stood out as the single biggest driver, linked to roughly 52% of the gap. Heavy drinking accounted for another 15.1%. Both habits are concentrated almost entirely among men in China, which produces a large difference in cancer rates between the sexes. Chronic liver disease and low fruit intake also contributed to the disparity.

In other words, in this Chinese population, men's excess cancer risk was largely a matter of behavior rather than biology.

Why was the UK picture so different?

In Britain, the analysis told a different story. Because British men and women have far more similar smoking and drinking habits, those factors no longer dominated the gap.

Instead, metabolic conditions became the leading measured driver of disparity:

• Obesity was the largest single contributor, but explained less than 8% of the gap.
• Smoking came next, accounting for 6.26%.
• Type 2 diabetes explained 3.51%.

That leaves almost 74% of the UK gap unexplained by the factors the study measured. The researchers note that future work needs to determine whether other major influences — such as environmental exposures or biological differences — account for the remainder.

What are the study's limits?

The study's conclusions carry caveats. The data come from only two countries, so the findings may not generalize to other populations. The UK Biobank and Shanghai cohorts also differ in demographics, environment, and healthcare access, which complicates direct comparison.

The unexplained share of the gap — whether 15% in China or 74% in the UK — signals that the researchers did not measure everything that matters. Risk factors outside the list of 11, including occupational exposures and inherited genetic variation, could fill part of that hole.

As with any observational study, the analysis identifies associations rather than proof of cause and effect.

What does this mean for cancer prevention?

The central message is that the cancer gap between men and women is not set in stone by biology alone. Its causes shift from country to country, shaped by cultural habits and the overall health of each population.

The researchers argue that cancer prevention plans should therefore be tailored to each population rather than copied from one country to another. In China, tobacco and alcohol control targeted at men could close a large share of the gap. In the UK, where smoking and drinking patterns converge between the sexes, addressing obesity and metabolic disease would likely matter more.

The findings appear in JAMA Oncology (DOI: 10.1001/jamaoncol.2026.3747).