Perhaps. Or maybe, people with healthier, more efficient lungs are able to walk faster without breathing heavier. In that case, breathing less might reduce the inhaled carcinogens, reducing the risk of lung cancer.

Looking at the actual research, the conclusions are carefully worded to avoid this sort of reporting.

Faster walking speed, whether self-reported or measured, is associated with a reduced risk of cancer development. This association appears to be partially mediated by lower inflammation and improved lipid profiles.

[–] cabb@lemmy.dbzer0.com 2 points 4 days ago

I think the results below might say that faster walkers tend to be at a healthier weight. Better lipid panels and less inflammation probably means fewer are overweight and obese.

[–] themeatbridge@lemmy.world 1 points 5 days ago

Probably. Or maybe, people who have healthier lungs don't need to breathe as much to efficiently exchange oxygen for CO2. So maybe breathing less protects against lung cancer by inhaling fewer carcinogens.

There are simply too many confounding variables to control for all of them. Research like this is important, and it's not the researchers' fault. Notice how the conclusions are carefully worded to specifically avoid exactly this sort of news article.