Cancer over diagnosed

Half prostate cancers found are dormant: Study

ALMOST half of prostate cancers diagnosed in Australia as a result of screening tests are “dormant” and would cause no harm if left undetected and untreated, Gold Coast researchers have found.

In an Australian-first study, led by Bond University, researchers estimated the extent of “over-diagnosis” in prostate cancer for the first time using statistical software and Australian Institute of Health and Welfare data.

Public health researcher Thanya Pathirana said prostate cancer over-diagnosis was a known adverse effect of screening for the disease, often leading to unnecessary and sometimes harmful procedures and treatments such as surgery, radiotherapy and hormone therapy.

Surgery to remove the prostate gland can result in incontinence and impotence. Psychological effects of a cancer diagnosis in many people can be mentally debilitating.

Dr Pathirana, of Bond University’s Centre for Research in Evidence-Based Practice, said the Australian estimates of men being diagnosed with dormant prostate cancers after screening were similar to results from trials in the US and Europe.

The Australian study, published in the medical journal BMJ Open, found the lifetime risk of being diagnosed with prostate cancer rose from 6.1 per cent in 1982 to 19.6 per cent in 2012 with a rapid increase following the introduction of prostate-specific antigen (PSA) screening in 1989.

Dr Pathirana said the results of the study corresponded to a “conservative estimate” of 41 per cent of prostate cancers being overdiagnosed as a result of screening.

PSA testing measures the amount of a protein in men’s blood. High levels can be an indication of cancer and may result in patients being referred for a biopsy or a magnetic resonance imaging scan.

Bond University’s Paul Glasziou, a professor of evidence-based medicine and one of the authors on the study, said the results clearly demonstrated Australia had been overdiagnosing prostate cancer for decades.

“We are detecting dormant cancers that would never have become symptomatic,” he said.

The researchers have called for general practitioners to talk more openly with men about the risks and benefits of PSA testing before screening them.

“Men still need to remain vigilant when it comes to early detection,” Professor Glasziou said. “However, they need to be informed and engage in shared decision making with their medical professionals about the harms of prostate screening and other associated procedures.”

Every year, about 3900 Queensland men are diagnosed with prostate cancer and 600 die from the disease. find out more at prostate.org.au.