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NEW YORK (Reuters Life!) - Mammography is less accurate at spotting breast cancer if a woman has had the disease before, according to a U.S. government-funded study.
Breast cancer survivors are more likely to develop new tumors than women without a history of breast cancer, but little is known in detail about screening for survivors.
The study, published in the Journal of the American Medical Association and based on information from the largest mammography registry in the United States, showed that screening does help detect breast cancer in survivors -- but not often enough.
"These findings and additional studies that are likely to be stimulated from this report should lead to improved (radiology routines)," said Robert Smith of the American Cancer Society, in a statement.
The study, led by Les Irwig of the University of Sydney in Australia, was the joint work of U.S. and Australian researchers, who compared nearly 120,000 mammograms -- half from breast cancer survivors, half from those without a comparable history of breast cancer.
Within a year of screening, 655 tumors were found in survivors, compared to 342 in the other women.
Seven cancers were found per 1,000 screens compared to four per 1,000 screens in women who had never had the disease.
But the procedure also missed tumors 11 percent more often in the survivors, even though these women had higher numbers of extra mammograms.
Survivors were also more likely to be told that the mammogram might be showing a cancer, when the woman actually didn't have any.
Cancers detected by symptoms, and not screening, were more than twice as common in survivors as well.
About one in eight women will develop breast cancer during their lifetime, but the chance of dying from the disease has been dropping recently and is now less than 3 percent, according to the ACS.
The ACS recommends mammograms once a year in women 40 and older, while the U.S. Preventive Services Task Force says once every two years in women over 50.
Reporting by Frederik Joelving at Reuters Health; editing by Elaine Lies