WA women have a poor understanding of what causes breast cancer, with many wrongly believing stress and faulty genes are the main culprits, research shows.
A study of more than 2700 women - 1100 with breast cancer - found some blamed factors such as powerlines, bruises and food additives for the cancer despite little evidence. Researchers from Curtin University, the University of WA and Cancer Council WA asked women to name risk factors for breast cancer and then asked those with breast cancer what they thought had caused it.
Women without cancer were quizzed on what they believed caused breast cancer.
Writing in the journal BioMed Central, the researchers said almost half of women with breast cancer felt mental or emotional factors were responsible for their disease. Many blamed stressful life events, which they saw as "triggers" for their cancer.
Women without breast cancer greatly overestimated the role of genetics, rating it the main risk factor, even though genetics and family history were thought to contribute to only 9 per cent of breast cancers.
More than three-quarters of these women linked genetics to breast cancer, but less than half believed lifestyle factors such as smoking and diet were a cause.
Chief investigator Lin Fritschi, from Curtin's school of public health, said most women had an opinion about what caused the cancer but often their beliefs were not backed by evidence.
"Many women without breast cancer think the major cause is genetics, when in fact family history is only associated with a minority of breast cancers," she said. "Women with breast cancer often feel their own cancers were caused by stress, when again there is little evidence of this."
Ms Fritschi said misconceptions about what caused the cancer were worrying. It was of particular concern that women who did not have it had an inflated perception of genetic risk.
It could hamper early detection and prevention because women with no family history of the disease might assume they were "in the clear" and lifestyle factors such as smoking did not matter.
"If women think only people with a family history get breast cancer, they're not to be concerned about getting a mammogram or checking the lump they find in their breast," Ms Fritschi said.