How credible is this paper? I see it's highly cited, but I also see that it claims that fungi are cancer causing but not also cancer preventing, which seems questionable.

Feel free to read other studies/sources: https://en.wikipedia.org/wiki/Causes_of_cancer cites other papers with similar stats, there are also many sub articles listed

> Over one third of cancer deaths worldwide (and about 75–80% in the United States) are potentially avoidable by reducing exposure to known factors.

> Common environmental factors that contribute to cancer death include exposure to different chemical and physical agents (tobacco use accounts for 25–30% of cancer deaths), environmental pollutants, diet and obesity (30–35%), infections (15–20%), and radiation (both ionizing and non-ionizing, up to 10%).

> less than 0.3% of the population are carriers of a cancer-related genetic mutation and these make up less than 3–10% of all cancer cases.