SOURCE: University of Calgary

University of Calgary

March 01, 2016 12:05 ET

PSA testing does not change prostate cancer mortality

Study authors dispute the value of PSA screening

CALGARY, AB--(Marketwired - March 01, 2016) - Canadian researchers have assessed the effects of PSA screening, and found that while screening increases the number of diagnoses of prostate cancer, the test has only minimally reduced mortality rates, if at all. While mortality rates from the disease have been decreasing, this study suggests the decline is more likely due to the evolution of treatment. The study results were published in the March 1 online edition of CMAJ Open.

The PSA test was introduced as a non-invasive prostate cancer screening tool in Canada in the early 1990s. A blood test, it measures the amount of prostate specific antigen (PSA) in a man's blood -- high levels of PSA may indicate the presence of cancer. By 2008, countries that adopted this screening tool saw prostate cancer rates rise, including Canada, which has among the highest rates in the world. Typically a very slow-growing cancer, the risk of developing prostate cancer rises with age, especially for men over 75.

"Screening causes substantial increases in the number of men diagnosed with prostate cancer, especially before 70 years of age," says Dr. James Dickinson, from the University of Calgary and lead author of the paper. "However, most would never have known about it otherwise, and died of other causes at a normal age."

Dickinson adds that treatments for prostate cancer such as surgery, chemotherapy and radiation cause harm, as they take both a physical and mental toll on the body. "Treatment is worthwhile for the five in 1000 men with cancers that would invade and kill, but not for the men with slow-growing cancers that do not: possibly over 120 per 1000," he says.

The study shows that mortality rates caused by prostate cancer began to decline two years prior to the widespread use of PSA tests after 1996, and have continued to drop by approximately 3.25 per cent annually.

"This pattern of decline in mortality rates began to occur earlier and is greater than could possibly be expected even from the most optimistic evaluation of screening," says Dickinson, professor in the departments of family medicine and community health sciences at the University of Calgary's Cumming School of Medicine and member of the O'Brien Institute for Public Health.

The team then began to look at other possibilities for the decline. They noted similar patterns of diagnoses and mortality rates in countries that started using the screening tool early. Conversely, in countries in Europe that delayed adopting the PSA test, an expected delay in increase of diagnoses was observed while the change in mortality rates was similar to that of countries using PSA tests.

"This suggests that the mortality drop is likely due to changes in patterns of treatment such as surgery, chemotherapy and radiation that occurred at that time in all these countries," says Dickinson. "There are also other possibilities such as changes in how deaths were reported."

Dickinson says the study suggests that most men who are not screened using the PSA test will likely never know they have cancer and will not be bothered by it. Those who develop advancing cancer should be diagnosed and treated when they feel symptoms.

The Canadian Task Force on Preventive Health Care suggests that men who are uncertain should discuss very carefully with their family doctor before choosing PSA screening.

About the University of Calgary

The University of Calgary is making tremendous progress on its journey to become one of Canada's top five research universities, where research and innovative teaching go hand in hand, and where we fully engage the communities we both serve and lead. This strategy is called Eyes High, inspired by the university's Gaelic motto, which translates as 'I will lift up my eyes.'

For more information, visit ucalgary.ca. Stay up to date with University of Calgary news headlines on Twitter @UCalgary. For details on faculties and how to reach experts go to our media centre at ucalgary.ca/news/media.

About the Cumming School of Medicine

The University of Calgary's Cumming School of Medicine is a leader in health research, with an international reputation for excellence and innovation in health care research and education. On June 17, 2014, the University Of Calgary Faculty Of Medicine was formally named the Cumming School of Medicine in recognition of Geoffrey Cumming's generous gift to the university.

For more information, visit cumming.ucalgary.ca/, or follow us on Twitter @UCalgaryMed

About the O'Brien Institute for Public Health
With more than 400 members, the University of Calgary's O'Brien Institute for Public Health is a virtual, interdisciplinary network integrating research groups, academics, health professionals, community leaders, and policy makers across the health continuum to catalyze excellence in population health and health services research. Together, O'Brien Institute members strive to produce new knowledge and evidence to inform, and help shape, public health agencies and health systems for the benefit of local, national and global communities - achieving the institute's vision of Better Health and Health Care. www.obrieniph.ucalgary.ca.            

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Contact Information

  • Media Contact
    Marta Cyperling 
    Media Relations Manager, Cumming School of Medicine
    University of Calgary
    403.210.3835
    mcyperli@ucalgary.ca