AGF s.r.l./REX/Shutterstock Ben 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 by the prostate gland; higher levels may suggest a tumour. After a worrying result, Stiller was diagnosed with prostate cancer two years ago, at just 48. After a biopsy and surgery, he is now cancer free. So should other men rush out to get tested?