Australian researchers say doctors are over diagnosing the most common thyroid cancer, creating an artificial epidemic that costs billions.

Associate Professor Suhail Doi from the Australian National University (ANU) says diagnoses of differentiated thyroid cancer have increased three-fold globally during the past 25 years, despite no change to the disease’s low death rate.

Dr Doi and his colleagues analysed international autopsy data, including from regions that had high and low instances of differentiated thyroid cancer, over five decades from the 1960s.

They found that incidental differentiated thyroid cancer has remained unchanged, confirming for the first time that the epidemic has been driven by increasing detections of cancer.

“Overly meticulous examinations are detecting the condition in the early stages and resulting in unnecessary surgeries,” said Dr Doi, a clinical epidemiologist at the ANU Research School of Population Health who also works as an endocrinologist.

“Active monitoring rather than intervention is appropriate in many cases, similar to how doctors treat prostate cancer today.”

Differentiated thyroid cancer usually involves kinds of tumours that do not progress to clinical forms of cancer.

Around 2,500 new cases of differentiated thyroid cancer will be diagnosed in Australia this year.

Thyroid cancer surgery has substantial consequences for patients, usually leaving them dependent on lifelong thyroid-replacement therapy, and possible further complications including damage to nerves and surrounding glands.

In 2019, the projected medical care costs for differentiated thyroid cancer in Australia are estimated to be more than $300 million.

“People with this type of thyroid cancer can sometimes live until normal life expectancy and usually die from other causes, so there is no point intervening if the cancer is acting in a benign way and not causing any problems,” Dr Doi said.

“Only some of these cases require treatment if and when the condition progresses to clinical forms of cancer.

“Ultimately, this research will help improve thyroid cancer patients’ quality of life and reduce avoidable burden on health systems.”