Dear Dr. Roach: Five years ago, I added five to six minutes of easy yoga, mostly sitting exercises, to my daily exercise routine. My PSA has gone down to the 0.9-1.1 range, from 4.3. This is for someone who has had two prostate biopsies through the years. My doctor now says that the odds of me having prostate cancer are about 1,500 to 1. A few others who have started doing the exercises also have seen their PSA number drop. — B.C.L.
Answer: I have two important comments about your story. The most significant is that there is pretty strong evidence that regular exercise, especially regular vigorous exercise (one study looked at men with at least three hours of vigorous exercise per week), decreases the risk of prostate cancer. The magnitude of the effect varies depending on the study, from 31 percent to almost 70 percent. However, the effect you have seen in your PSA result is much better than usual: In a study on exercisers versus non-exercisers, the PSA dropped by 4 percent in the exercise group (who had other lifestyle interventions as well), compared with an increase of 6 percent in the control group.
However, exercising right before getting your PSA drawn can lead to a spurious elevation in the result. This just has to do with the activity releasing premade PSA: Sexual activity can do this as well.