BEIJING, July 10 (Xinhuanet) -- Women diagnosed with breast cancer may be undergoing surgery or gruelling treatment they do not need, according to a study. Researchers say as many as one in three cases of breast cancer detected by screening prove harmless.
Karsten Jorgensen and Peter Gotzsche of the Nordic Cochrane Centre in Copenhagen analyzed breast cancer trends at least seven years before and after government-run screening programs for breast cancer started in parts of Australia, Britain, Canada, Norway and Sweden.
The research was published Friday in the BMJ, formerly known as the British Medical Journal.
Researchers said that screening for cancer may lead to earlier detection of lethal cancers but also detects harmless ones that will not cause death or symptoms.
¡°The detection of such cancers, which would not have been identified clinically in someone¡¯s remaining lifetime, is called overdiagnosis and can only be harmful to those who experience it,¡± the researchers said.
¡°As it is not possible to distinguish between lethal and harmless cancers, all detected cancers are treated. Overdiagnosis and overtreatment are therefore inevitable.¡±
The authors pointed to post-mortem data that has shown that about 37 per cent of women aged 40 to 54 ¡°who died from causes other than breast cancer, had lesions of . . . cancer at autopsy¡±. About half of these lesions would have been picked up in screening and some would have been treated, they said.
"This information needs to get to women so they can make an informed choice," Jorgensen said. "There is a significant harm in making women cancer patients without good reason."
Jorgensen said that for years, women were urged to undergo breast cancer screening without them being informed of the risks involved, such as having to endure unnecessary treatment if a cancer was identified, even if it might never threaten their health.