My inclination is that this could still just be a selection effect. For people who are prone to cancer, you are probably dead by 80.
https://www.cancer.gov/about-cancer/causes-prevention/risk/a...
And then always researchers try to find a clue in the patient and see like oh hey they have more iron, iron must be the solution, but maybe the person just didn't get cancer because (s)he had a healthy lifestyle and relatively little stress.
Prostate cancer is surprisingly prevalent but (commonly) slow-proliferating, and is often “beaten to the punch” by other causes of mortality.