The primary problem is that there’s well documented evidence of the statistical connection between long term GI inflammation and development of certain cancers. The fact that people who are on prescription PPI’s tend statistically to be those developing cancers, regardless of H. pylori involvement, is not surprising given that people prescribed PPI’s are likely those with more significant inflammatory disease.
I guess I’ll have to read the article to see if there’s a control for degree of inflammatory disease, or if they managed to isolate PPI use as a single factor (which I’d be surprised if they did). Unless they controlled for degree of inflammation, then this is more correlation than causation…