Frequent use of antibiotics has been linked to a greater risk of breast cancer, say researchers who studied thousands of American women and found that those who took the drugs most often had twice the risk of the disease.
The study uncovered a relationship between greater use of antibiotics and a heightened risk of breast cancer, but researchers sought to temper their findings by cautioning that they had only highlighted an association, not a causal link.
"This is potentially worrisome, but we don't know why this connection exists, we only have an observation," said Dr. John D. Potter, director of the division of public health sciences at the Fred Hutchinson Cancer Research Center in Seattle and an author of the report. "At the moment, we need to see these results replicated with more research before drawing any conclusions."
The study, published in the latest issue of The Journal of the American Medical Association, is now the second to draw a connection between antibiotics and breast cancer, informs &to=http://www.nytimes.com' target=_blank>NYTimes.com
In the new study on more than 10,000 women, those who used the most antibiotics - who had more than 25 prescriptions, or who took the drugs for at least 501 days - faced double the risk of developing breast cancer over an average of about 17 years, compared with women who did not use the drugs.
"This is an important study, as it appears to be the first major work to describe a possible association between antibiotic use and the increased risk of cancer," said Jeanne Calle, the American Cancer Society's director of analytical epidemiology, reports &to=http://www.globeandmail.com' target=_blank>GlobeAndMail