Over 13 years, routine PSA testing reduced the number of prostate cancer deaths by 21%. But still, researchers say it is too soon to introduce routine screening for the disease.
Worldwide, prostate cancer is the second most common cancer in men. In 2008, there were approximately 910,000 cases of prostate cancer globally, and this number is expected to almost double to 1.7 million by 2030.
Prostate cancer is very rare among men under the age of 40, but risk of the disease significantly increases after the age of 50. In the US, around 6 in 10 prostate cancer cases are found in men over the age of 65.
Although there is no routine screening program for prostate cancer, men can opt to be screened for the disease with a prostate-specific antigen (PSA) test. This measures the levels of PSA in the blood - a substance the prostate secretes. High levels of the antigen can be a sign of prostate cancer.
Recommendations for prostate screening vary. For example, the US Preventive Services Task Force recommend that men should only be screened for prostate cancer if they have symptoms.
However, the American Cancer Society recommend that men aged 50, who are at average risk of prostate cancer and are expected to live 10 years or more, should talk to their doctor about prostate cancer screening.
There is also no organized prostate cancer screening in England, but there is a Prostate Cancer Risk Management Programme. This aims to ensure men who are worried about their risk of prostate cancer receive enough information to decide whether they should have a PSA test.
Routine PSA testing reduced prostate cancer deaths by 21% over 13 years
In 1993, the European Randomised study of Screening of Prostate Cancer (ERSPC) was launched in order to see whether routine PSA testing for men would reduce the number of deaths from prostate cancer.
The study - long-term results of which have recently been published in The Lancet - involved more than 162,000 men aged 50-74 from eight countries; France, Finland, Belgium, Italy, the Netherlands, Spain, Sweden and Switzerland.
- Around 233,000 new cases of prostate cancer will be diagnosed in the US this year
- Behind skin cancer, prostate cancer is the most common cancer in American men
- The majority of men diagnosed with prostate cancer do not die from it. More than 2.5 million American men who have been diagnosed with the cancer at some point are alive today.
Every 4 years, the men were randomized to receive either PSA screening or no screening. This occurred every 2 years for men from Sweden. If men who received screening had a PSA concentration higher than 3.0 ng/ml, they were referred to have a biopsy.
During the 13-year follow-up, 7,408 cases of prostate cancer were diagnosed in men who underwent PSA testing, while 6,107 cases were found in men who received no screening.
After 9 years, results of the study revealed that prostate cancer screening appeared to reduce the number of prostate cancer deaths by 15%. At 11 years after study baseline, screening seemed to reduce the number of prostate cancer deaths by 22%. After this point, no further reduction in prostate cancer deaths was seen as a result of screening.
Overall, the number of prostate cancer deaths reduced by 21% among men who were screened, compared with those who had no screening. Furthermore, men who were screened had a lower risk of advanced prostate cancer and a 27% lower risk of dying from prostate cancer.
In addition, the researchers found that the absolute benefit of prostate cancer screening rose steadily during the follow-up. After 9 years, 1,410 men needed to undergo screening in order to prevent one prostate cancer death. This reduced to 781 after 13 years.
'The time for population-based screening has not arrived'
Study leader Prof. Fritz Schröder, of the Erasmus University Medical Center in the Netherlands, says it is clear that PSA screening "delivers a substantial reduction in prostate cancer deaths, similar or greater than that reported in screening for breast cancer."
But despite this, he believes it is too soon to recommend routine screening for prostate cancer.
He notes that overdiagnosis occurs in around 40% of prostate cancer cases detected by screening, and that this can lead to overtreatment and common side effects, including incontinence and impotence.
Prof. Schröder adds:
"The time for population-based screening has not arrived. Further research is urgently needed on ways to reduce overdiagnosis preferably by avoiding unnecessary biopsy procedures, and reducing the very large number of men who must be screened, biopsied, and treated to help only a few patients."
He notes that a promising approach could be multiparametric MRI technology. "[This] may be able to selectively diagnose aggressive prostate cancers and avoid the diagnosis of many inconsequential tumors that generally grow so slowly that most men will die of other causes." he explains.
"But for now, men must be given well-balanced information, including the screening harms of overdiagnosis and overtreatment."
In an editorial linked to the study, Ian Thompson, of the University of Texas Health Science Center, and Catherine Tangen, of the Fred Hutchinson Cancer Research Center in Seattle, WA, say that although this research demonstrates the benefits of screening, "PSA-based screening is imperfect," supporting the points made by Prof. Schröder regarding overdiagnosis and side effects of treatment.
However, they point out that 60% of cancers detected in this study were low-risk tumors that have low rates of disease progression, even if they are just monitored without treatment - a strategy known as active surveillance.
"Although most of these patients currently receive treatment, with active surveillance yielding disease-specific survival of 97% at 10 years, an increasing proportion of patients are requesting this management with treatment given only if disease progression develops," they explain.
"If most of the patients with low-risk prostate cancer in the intervention group were managed with active surveillance, the side-effects of treatment would be substantially reduced."
Last month, Medical News Today reported on a study by researchers from the Harvard School of Public Health in Boston, MA, claiming vasectomy is linked to a small increased risk of aggressive prostate cancer.