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Study Links Antibiotics, Breast Cancer - 2004-02-17

New, potentially troubling research has found that women who take antibiotics are at a significantly higher risk of developing breast cancer, a disease that strikes more than one million women around the world each year. Experts say it's too soon to draw any conclusions.

Antibiotics, more than any other treatment, have revolutionized the practice of medicine, curing once fatal diseases such as pneumonia.

But a new ground-breaking study of 10,000 U.S. women, published in this week's Journal of the American Medical Association (JAMA), has found that those who take antibiotics are up to two times more likely to develop breast cancer. The risk increased with the number of prescriptions.

Roberta Ness is head of the department of epidemiology at the University of Pittsburgh in Pennsylvania. Dr. Ness, in an editorial in JAMA, says the increased risk of breast cancer may have to do with the frequent use of antibiotics to treat long standing infections.

"Chronic infections have been shown to cause chronic inflammation. And chronic inflammation has been shown to cause a series of different cancers, including colon cancer, liver cancer, stomach cancer and a variety of others," she said.

Investigators found that it did not matter what type of antibiotics was used, what they were used for or for how long by women at highest risk.

Dr. Ness notes the study was based on the records of a population of women and not on studies of the effects of antibiotics. For that reason, she says more research is needed.

Rather than being scared, experts say women should discuss the use of antibiotics with their doctors.