Lung cancer screening tests aimed at smokers with few symptoms of the disease may be causing more harm than good while experts try to assess the merits of a co-ordinated screening program in Australia, doctors warn.
Some Australian radiology clinics are offering smokers CT scans of their lungs to see if they have cancer, which is easier to treat if detected early.
While early detection through scans may improve someone's chance of survival, experts say smokers are more likely to get a false positive result that leads to potentially harmful biopsies and surgery.
In rare cases, those investigations can be fatal because of an infection or bleeding, for example.
There is also a significant risk that somebody will be "over-diagnosed" with a cancer that is not going to cause any clinically significant harm during their lifetime. The trouble is, doctors cannot always differentiate between the cancers that will and won't cause harm.
Dr Fraser Brims, a physician at Sir Charles Gairdner Hospital in Perth, said more research was required to assess the pros and cons of co-ordinated lung cancer screening for people at high risk, such as those aged over 50 who had smoked a pack a day, on average, for 30 years.
In current smokers, he said about half would have an abnormality detected on a CT scan of their lungs, but for 95 per cent of those people, that abnormality would not be cancer.
"We don't want people with abnormalities to have high [radiation] dose scans, biopsies and surgery when they might not need it," he said.
Dr Brims said screening smokers with CT scans had been shown to reduce deaths by about 20 per cent in the US, where authorities were implementing screening for some high-risk people.
However, he said Australia needed to do more research on whether those findings applied here.
In the Medical Journal of Australia, he and two colleagues wrote: "The challenge facing Australia is the translation of international results into sustainable, cost-effective clinical practice, ensuring that the desired benefit outweighs the known harms, at the same time as enhancing tobacco control policies."
Last year, the Australian government's standing committee on screening said it did not support lung cancer screening for either the general population or high-risk people and would continue to evaluate emerging research.