Researchers have found that according to existing evidence from randomized controlled trials, routinely screening large populations of men for prostate cancer is not recommended. Their report appears in today’s issue of the BMJ (British Medical Journal). Another study published today in the same medical journal, though, recommends a single test at 60 years of age to identify males most like to develop and possibly die from prostate cancer. These patients could then be monitored, while others would be exempt from further tests.
The authors inform that prostate cancer is common among men throughout the world. Prostate cancer screening is widely used in several countries; however, it is a controversial subject, because experts do not seem to be able to agree on whether the benefits of screening exceed the potential drawbacks, which include harm, costs, over-diagnosis and over-treatment of healthy individuals.
A review of two randomized controlled trials in 2006 determined that the evidence to support routine prostate cancer screening was not compelling. Four new trials have been published since then.
Professor Philipp Dahm and tream at the University of Florida examined the six trials, consisting of 387,286 men. They found that screening does not have a significant impact on mortality (death rate), it has the risk of over-treatment, but helps in the diagnosis of prostate cancer at an earlier stage.
The authors of this current study say there is not enough evidence to recommend actively inviting all males of a certain age to get screened for prostate cancer, as is the case with breast cancer for women. The writers add that men need to be made aware of the uncertainties associated with screening.
Professor Hans Lilja and team demonstrate that one PSA (prostate-specific antigen) level test at the age of 60 years can fairly accurately predict a man’s lifetime risk of prostate cancer diagnosis, and risk of death from the disease.
The authors reveal that 90% of deaths from prostate cancer occur in men with the highest levels of PSA at the age of 60, while sixty-year-old men with moderate or low PSA levels had extremely low rates of prostate cancer or death by the time they reached 85 years. Half of all the sixty-year-old men would be exempt from further prostate cancer screening, which carries the risk of over- diagnosis and treatment.
Gerald Andriole, Chief of Urologic Surgery at Washington University School of Medicine, in an accompanying editorial, suggests that PSA testing should be tailored to individual risk.
He believes that young males with a strong family history, and/or higher baseline PSA levels, should be monitored closely, while elderly individuals and people considered low risk should receive no follow-up or infrequent ones.
Andriole said:
Approaches such as these will hopefully make the next 20 years of PSA based screening better than the first 20.
Prostate cancer only affects men. Cancer starts to grow in the prostate – a gland in the male reproductive system.
The prostate is an exocrine gland of the male reproductive system, and exists directly under the bladder, in front of the rectum. An exocrine gland is one whose secretions end up outside the body e.g. prostate gland and sweat glands. It is approximately the size of a walnut.
The urethra – a tube that goes from the bladder to the end of the penis and carries urine and semen out of the body – goes through the prostate.
There are thousands of tiny glands in the prostate – they all produce a fluid that forms part of the semen. This fluid also protects and nourishes the sperm. When a male has an orgasm the seminal-vesicles secrete a milky liquid in which the semen travels. The liquid is produced in the prostate gland, while the sperm is kept and produced in the testicles. When a male climaxes (has an orgasm) contractions force the prostate to secrete this fluid into the urethra and leave the body through the penis.
As the urethra goes through the prostate: the prostate gland is also involved in urine control (continence) with the use of prostate muscle fibers. These muscle fibers in the prostate contract and release, controlling the flow of urine flowing through the urethra.
The Prostate Produces Prostate-specific antigen (PSA)
The epithelial cells in the prostate gland produce a protein called PSA (prostate-specific antigen). The PSA helps keep the semen in its liquid state. Some of the PSA escapes into the bloodstream. We can measure a man’s PSA levels by checking his blood. If a man’s levels of PSA are high, it might be an indication of either prostate cancer or some kind of prostate condition.
It is a myth to think that a high blood-PSA level is harmful to you – it is not. High blood PSA levels are however an indication that something may be wrong in the prostate.
Male hormones affect the growth of the prostate, and also how much PSA the prostate produces. Medications aimed at altering male hormone levels may affect PSA blood levels. If male hormones are low during a male’s growth and during his adulthood, his prostate gland will not grow to full size.
In some older men the prostate may continue to grow, especially the part that is around the urethra. This can make it more difficult for the man to pass urine as the growing prostate gland may be causing the urethra to collapse. When the prostate gland becomes too big in this way, the condition is called Benign Prostatic Hyperplasia (BPH). BPH is not cancer, but must be treated.
Click here to read about prostate cancer in more detail.
Mia Djulbegovic, Rebecca J Beyth, Molly M Neuberger, Taryn L Stoffs, Johannes Vieweg, Benjamin Djulbegovic, Philipp Dahm
BMJ 2010; 341:c4543 doi: 10.1136/bmj.c4543 (Published 14 September 2010)
Andrew J Vickers, Angel M Cronin, Thomas Björk, Jonas Manjer, Peter M Nilsson, Anders Dahlin, Anders Bjartell, Peter T Scardino, David Ulmert, Hans Lilja
BMJ 2010; 341:c4521 doi: 10.1136/bmj.c4521 (Published 14 September 2010)
Written by Christian Nordqvist