We have known since 1935 with the publication of Arnold Rich's autopsy study that there is a large pool of latent, clinically insignificant prostate cancer in the male population which increases with age. By the age of fifty, 30-40 per cent of males will harbor a clinically insignificant focus of prostate cancer. The vast majority succumb to old age before the prostate cancer bothers them. These prostate cancers are the incidental findings at post mortem exam.
Left Image: Prostate diagnosis and treatment was rather barbaric during the middle ages. We have come a long way since then.Image ofDie Saege.jpg courtesy ofWikimedia Commons.
Prostate cancer is a slow growing indolent disease with a 99 per cent 5 year survival after diagnosis. The incidence of latent prostate cancer is estimated to be one half of the male population 65 and over (7 million of the 14 million males), yet there are only 30,000 deaths per year. This means the average male has a 0.5% chance of dying from prostate cancer, (or a 99.5 chance of dying from other causes, not prostate cancer).
PSA screening programs send the screened patients to trans-rectal ultrasound guided biopsy which finds these latent prostate cancers, many of which should not be treated. Mainstream conventional treatment involves radical prostatectomy, radiation therapy, or hormonal castration. The first two are associated with adverse effects of incontinence, and erectile dysfunction. Treatment with androgen blockade, (a form of chemical castration) is associated with increased mortality and osteoporosis.
One of the unmistakable impacts of wide scale PSA screening for prostate cancer has been the eradication of advanced cases over the past two decades. For example, during my training years in the nuclear medicine department at Rush Medical School in Chicago in the 1970's, we followed dozens of patients with metastatic prostate cancer on serial bone scans. (see left image) This is rarely seen today. The advanced prostate cancer case is a rare bird driven to extinction, seen only occasionally.
Stephen Strum, MD, an oncologist from Oregon writes in this March 2009 NEJM article, "The nature of the patient diagnosed with PC has dramatically changed since the introduction of PSA in 1987. Almost gone are men presenting with advanced local or distant Prostate Cancer."
Like the vanishing American Buffalo, these advanced metastatic prostate cancer cases have been hunted to the point of near extinction by the American PSA Screening Test.
left Image:Vanishing Rare Bird, Metastatic ProstateCancer Diagnosis. Bone Scan shows prostate cancer involving skeleton (bone metastasis, red arrows) courtesy of wikimedia commons.
The Vanishing Buffalo- Hunted to Extinction
Stanford's Dr. Thomas Stamey, the first to advocate PSA screening in 1987, has come full circle,and no longer recommends PSA screening. Stamey found the abundance of advanced cases from the early years of PSA Screening are gone, and the PSA test has become useless. Stamey declares, "The prostate specific antigen era in the United States is over for prostate cancer".
Left Image: American Buffalo hunted to near extinction. Courtesy of wikimedia commons.
Stamey's data shows there was a substantial decrease in correlation between PSA levels and the amount of prostate cancer - from 43 percent predictive ability in the first five-year group down to 2 percent in the most recent one. "Our job now is to stop removing every man's prostate who has prostate cancer," said Stamey. "We originally thought we were doing the right thing, but we are now figuring out how we went wrong."
Organizations Against Screening
In 1997, the American Cancer Society changed its position and no longer recommends screening under the leadership of Otis Brawley MD, their chief Medical Officer who declined PSA screening for himself, personally. Otis Brawley, MD says."twenty-three organizations of experts from the Canadian Urology Association to the American College of Physicians to the U.S. Preventive Services Task Force recommend against screening...the predominance of professional expert opinion is that (PSA screening) is unproven and should not be done."
What is the Clinical Utility of PSA Test ?
According to Dr Bicker's August 2009 article in Anticancer Research, PSA is now commonly regarded as an indicator of prostate volume, and is not independently diagnostic or prognostic in prostate cancer. Even though mass screening of asymptomatic men with the PSA test is no longer recommended, the PSA test remains a very useful tool in the diagnosis and follow up of prostate cancer. For example, the PSA is useful as a cancer marker to follow cancer recurrence, progression or regression after treatment.
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