Column: New ways to manage prostate cancer

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  • Chris O’Neill

    “Genetic testing also can predict whether the cancer is likely to spread beyond the prostate.”

    As with PSA screening, genetic testing has not been demonstrated to improve overall survival.

    • Clint Bahler

      Chris-

      Thanks for your thoughts and you bring up a good point. It’s hard to perform a study showing an overall survival benefit because it’s difficult to keep men from getting PSA testing in the control group (non-screen). For example, in the U.S. study testing PSA screening (PLCO), more men reported PSA testing in the group that was supposed to be without testing than in the group that was supposed to get testing during the study. This was covered up in the initial publication, which has created some recent headlines:
      http://www.medscape.com/viewarticle/863171
      http://www.nejm.org/doi/full/10.1056/NEJMc1515131?af=R&rss=currentIssue

      Good studies do exist showing a significant reduction in death from prostate cancer due to PSA screening. One example is the Goteborg/Swedish trial (1). In this study PSA screening was done every 2years. 20,000 were randomized and we now have 18year follow-up. They found a 42% reduction in prostate cancer death in the screen group with 139 screened per life saved and 13 diagnosed with prostate cancer per life saved.

      There will be an estimated 26,000 men who die of prostate cancer in the U.S. in 2016 (3rd highest of all male cancers). Between 1975 and 1993, deaths from prostate cancer increased by 25%. Since 1993, which is shortly after PSA was introduced, deaths from prostate cancer have decreased by more than 50% (http://seer.cancer.gov/statfacts/html/prost.html)! Prostate cancer had the largest percent decline in mortality of any carcinoma between 2002 and 2011 (www.cancer.gov). Certainly there are other advances during this time, but none that have significantly improved survival.

      The trouble with PSA screening is that it can lead to over treatment because it picks up slow growing tumors as well as aggressive tumors. The slow growing tumors (Gleason 6) are very unlikely to spread or cause symptoms and so treatment should be avoided. MRI biopsy and genetic testing (of the prostate biopsy itself) enable us to feel more confident that we have found all the aggressive cancer and thus more comfortable watching Gleason 6 tumors. In this case, genetic testing is not being used to increase survival, but to prevent over-treatment.

      Thanks,
      Clint Bahler, MD, MS
      Urology
      IU-Health, office 317.688.5504

      (1) Hugosson J, Carlsson S, Aus G, Bergdahl S, Khatami A, Lodding P, Pihl CG,
      Stranne J, Holmberg E, Lilja H. Mortality results from the Göteborg randomised
      population-based prostate-cancer screening trial. Lancet Oncol. 2010
      Aug;11(8):725-32.