This was done in Guangzhou where I lived for years until 2018. The incidence of smoking amongst males still higher - gut guess of 30-40% adult males are smokers in the city and province. So in their cohort one would expect to be seeing still living relatives of young adult smokers who are also smokers.
Interesting that it’s sold as supplement for joint and related tissue repair and yet first big science study with observable results is about cancer.
Other interesting point is that it’s study of cancer. And that is simply because China still has huge numbers of smokers and the health cost is stratospheric.
Is it actually stratospheric though, when you take out QOL year adjustments? Other studies, such as this one in Finland[1], found that when you don’t take into account QOL adjustments for the smoker that smoking is actually a net benefit for society because the smokers die earlier and don’t draw on the very expensive late life healthcare.
To me it is plausible that in a time of great social and economic change, the odds of behavioral confounds in observational studies might increase. Non-stationarity everywhere.
That said, a meaningful result here would be welcome.
