Does Prostate Cancer Screening Reduce Mortality Rates?

NEW YORK, April 14, 2011 /PRNewswire/ -- Dr. David Samadi, Vice Chairman, Department Urology, and Chief of Robotics and Minimally Invasive Surgery at The Mount Sinai Medical Center in New York City, expressed concern today regarding the conclusions of a study published this month in the British Medical Journal (BMJ).  Following a group of 9,000 men for 20 years; 1,500 of whom were screened for prostate cancer every three years, with the rest functioning as a control, the study set out to determine the effectiveness of screening with regard to prostate cancer mortality rates.  Despite the fact that the screened group had a higher survival rate, the study is being cited in many parts of the medical community as proof of the questionable efficacy of regular prostate cancer screening, a fact that Dr. Samadi says, "... results in a confusing message to older men who may have prostate cancer."

(Photo: http://photos.prnewswire.com/prnh/20110414/NY83545 )

The conclusions presented in the BMJ study run contradictory to others, such as one published in the New England Journal of Medicine (NEJM) in 2009. Conducted across seven countries in Europe and involving over 162,000 subjects, nearly twenty times the test group of the more recent BMJ study, the NEJM study showed a substantial 27% decrease in prostate cancer mortality rates in the segment that underwent regular screening.  Dr. Samadi says, "It is important when reading about these kinds of studies to look beyond the results and understand the specific parameters of the testing processes that were used.  The final number is not the entire picture and can lead you to make incorrect conclusions.  While both studies are based on the same premise, their outcomes are very different due to variances in testing procedures and the number of men studied."

Dr. Samadi goes into detail about some of the factors that call the new study's validity into question, citing the lack of PSA (Prostate-Specific Antigen) testing in the early stages of the BMJ trial as the largest concern.  PSA testing was not included in the BMJ study until 1993, 6 years after its start. Prior to that, only digital rectal exams were used for screening, which are not nearly as accurate a test as PSA.  Samadi said, "A concern I have with how this study was conducted is that PSA levels were not monitored for the first six years.  Early screening was based entirely on digital rectal exams, which we now know are not an accurate method for detecting prostate cancer when used alone.  The larger study published in the NEJM showed that regular PSA testing improved prostate cancer detection and outcomes, highlighting a shortcoming of the methods used in the BMJ study."

The BMJ study spans 20 years, 14 years following the introduction of PSA, compared to an average of 9 years in the NEJM study.  The benefit of the longer length of follow-up in the BMJ study, however, may be outweighed by the small number of men actually diagnosed with prostate cancer by screening.  Only 43 men in the BMJ study were diagnosed with screening, compared with 6000 men in the NEJM study.  This difference may explain the discrepancy in outcomes between the studies.    Additionally, improvements in prostate cancer treatment over the study period may have underestimated the value of early detection.  "We need to keep in mind that a lot has changed in cancer treatment over the course of 20 years, especially with the introduction of robotic prostatectomy surgery." said Samadi. "Robotic surgery, which derives its best results from the early detection of prostate cancer, wasn't available for the first two thirds of the BMJ study.  This fact, along with the lack of early PSA screening during the trial, makes its relevance to the current state of prostate cancer screening and treatment questionable."

In addition to being the second leading cause of cancer death in men, prostate cancer can result in serious health problems in men who might die from other causes.  Such problems include painful metastases, blockage of the urinary tract, and bone fractures. Dr. Samadi feels that due to these other conditions, assessing the worth of screening based on overall survival numbers alone is not advisable.

"Curing the patient of cancer is not the purpose of screening; it is the purpose of treatment.  The mark of effective screening is the percentage of found instances of prostate cancer and how advanced the cancer is at the time of diagnosis," states Samadi, who then concluded, "The BMJ study does state that those men who received regular screening were discovered to have smaller tumors which were less likely to have spread.  The detection of prostate cancer before it has metastasized plays a large role in the successful treatment of the disease and the prevention of non-fatal health concerns, such as painful metastases or spine fractures.  This study, despite its conclusions about mortality rates, proves that regular PSA screening gives patients the best chance of detecting the disease while it is still curable. While there have been recent studies that call PSA testing into question, it's my opinion that it's currently one of the best tools that we have for a proper diagnosis of prostate cancer." - A position backed by information presented in the NEJM.

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SOURCE Smart-surgery.com