Public not being informed about dangers of medical overdiagnosis

A national survey reveals that only one in ten Australians report being told about the risk of overdiagnosis by their doctors, according to research published today in the scientific journal PLOS ONE.

The increasingly recognised problem of overdiagnosis happens when someone is diagnosed with a disease that will never cause them any harm, often as a result of healthy people being screened for diseases such as breast or prostate cancer. Overdiagnosis can be harmful due to unnecessary labelling and treatment.

The telephone survey (mobile and landline) of 500 Australians was the first time any where in the world the general community has been asked about their knowledge and views on overdiagnosis.

Along with their benefits in saving lives, screening programmes can cause people harm, including overdiagnosis. A recent inquiry in the UK estimates 1 in 5 cancers diagnosed via breast cancer screening may be "overdiagnosed"—meaning the cancers would never go on to harm the women. For prostate cancer screening, the United States Preventive Services Task Force estimates as many as 1 in 2 cancers may be overdiagnosed.

Given this evidence, the national survey asked people if they had been screened for breast or prostate cancer, and if so, whether they had been informed about the risk of overdiagnosis.

For prostate cancer, over 80% of men screened said they were not told about the risk of overdiagnosis, and for breast cancer, almost 90% said they were not informed about overdiagnosis.

Overall only one in ten people said they'd been told about overdiagnosis, and 93% of those surveyed wanted to see people given information on the harms of screening, as well as its benefits.

Author Professor Kirsten McCaffery of the Sydney University says "Our survey results show we need to better inform the community about the harms as well as benefits of screening including the important harm of overdiagnosis."

A recent US analysis in Health Affairs estimated that for breast cancer screening alone, along with screening benefits, more than 20 000 women a year in the US may be overdiagnosed, at a cost of more than US $1 billion. Another cause of overdiagnosis arises because disease definitions are widened to include people with mild problems or at very low risk of illness, often by experts with financial conflicts of interest. Almost 80% of people surveyed believed it was inappropriate that the experts who define disease had financial relationships with pharmaceutical companies.