Breast cancer screening more 'harmful' than helpful
Breast cancer screening programs can cause more harm than good, according to a Danish professor who suggests women should not get screening mammograms at all.
Medical researcher Professor Peter Gotzsche argues that for every three or four lives saved by a widespread mammogram program, there is a risk of up to nine lives lost from the harm caused by radiography and other medical interventions.
But an Australian surgeon has refuted the claims, saying it would be a "tragedy" if more women came to him with "large, more advanced cancers" because they did not have screenings done.
Mammogram still best option: Experts
Early detection of breast cancer fact sheet
Professor Gotzsche told the ABC's 7.30 program that "mammography screening is harmful".
Over the past two weeks Professor Gotzsche has been touring Australia presenting his findings that preventative screening does not reduce mortality rates.
"What you have heard about breast screening is that it reduces breast cancer mortality usually by 30 per cent. That's probably also what you have heard here in Australia. It's not true," his lecture stated.
Medical imaging showing a breast screen. Source: AAP
"Those who might avoid dying from breast cancer are neutralised or cancelled out by those who are actually killed by having a therapy they did not need because they are over diagnosed breast cancer."
Improved cancer detection leading to more treatments is a key factor in the analysis.
Over the past two decades screening technology has improved and more cancers, particularly small ones, are being detected sooner.
"It's not a good idea to find cancers early because most of what you find on screening are over diagnosed cancers," Professor Gotzsche said.
"Since we cannot distinguish between dangerous and harmless cancers we need to treat all of them.
"When you treat over-diagnosed women - that means healthy women with radiotherapy - you kill some of them because some of them develop lung cancer or heart disease."
Australian breast surgeon refutes claims
But Dr Bruce Mann, the head of surgery for The Breast Service, disagrees with Professor Gotzsche's claims.
"What he's referring to is the rare side effects of radiotherapy that can occur," Dr Mann said.
"Particularly with old radiotherapy techniques the rate of heart disease was higher. That's being addressed by newer techniques."
Dr Mann said the true estimate of over-diagnosis was 10-15 per cent, not 50 per cent.
"The idea of over-diagnosis suggests that there are cancers that if left alone, will disappear. In clinical practice I've never seen it, my colleagues have never seen it," he said.
"I don't want to have a larger proportion of women coming to see me with large, more advanced cancers. It would be a tragedy."
Professor Gotzsche says "mammography screening is harmful”. Source: AAP
Clinicians are confident the problems that stem from over-diagnosis will be reduced when scientists can differentiate between so-called harmless cancers and those that do have the potential to kill.
"There's a genomic revolution going on in medicine which will tell us exactly what sorts of cancers are likely to progress quickly and which aren't," Jim Bishop from Cancer Australia said.
"But we don't have that [data] at the moment so every breast cancer is being discovered must be regarded as a threat to that woman."
The United Kingdom recently reviewed the research and, after concluding that some women were dying as a result of unnecessary treatment, now gives women more details about the risks of mammograms.
Australian breast specialists caution women to continue using the breast screening program.
Australia's national breast screening program began in 1991. In the most recent reported screening cycle, a total of 1.8 million women, or 56 per cent of the targeted population, had come in for their regular mammogram.
It recommends women be screened every two years.
