Researchers have revealed that Australians are increasingly being diagnosed with potentially harmless cancers, which if left undetected or untreated, may expose them to unnecessary surgeries and chemotherapy.

The research, published in the Medical Journal of Australia, drew on data from the Australian Institute of Health and Welfare to compare how the lifetime risk of five cancers had changed between 1982 and 2012. The study shows compared to 30 years ago, Australians are much more likely to experience a cancer diagnosis in their lifetime. "Cancer treatments such as surgery, radiotherapy, endocrine and chemotherapy carry risks of physical harms," said the study authors from Bond University, University of Sydney and Griffith University in Australia.

"In the absence of overdiagnosis, these harms are generally considered acceptable. In the context of overdiagnosed cancers, however, affected individuals cannot benefit but can only be harmed by these treatments," authors added.

The figures suggest that in 2012 24 per cent of cancers or carcinomas in men were overdiagnosed. These included 42 per cent of prostate cancers, 42 per cent of renal cancers, 73 per cent of thyroid cancers and 58 per cent of melanomas. For women, 18 per cent of cancers or carcinomas were overdiagnosed, including 22 per cent of breast cancers, 58 per cent of renal cancers, 73 per cent of thyroid cancers and 58 per cent of melanomas.

The figures are significant because of the harm that can occur from cancer treatment of patients who would never have had symptoms in their lifetime. The authors also refer to separate studies showing overdiagnosis could be linked to psychological problems. "For example, men's risk of suicide appears to increase in the year after receiving a prostate cancer diagnosis," researchers said. According to the researchers, It is the first time that the risk of overdiagnosis has been quantified across five cancers, anywhere in the world."

The findings also suggest an important role for health services such as the Australian Institute of Health and Welfare, in detecting potential overdiagnosis and alerting health policy decision makers to the problem early on.