Ben Stiller: now cancer freeAGF s.r.l./REX/ShutterstockBen Stiller’s life was saved because he had a screening test for prostate cancer. Now he’s urging others to follow his lead. Stiller’s logic sounds irrefutable. But he’s dead wrong. The US actor is recommending a test that detects blood levels of prostate-specific-antigen, or PSA, a substance produced...