Thyroid disorders do not appear to increase the risk of breast cancer, according to researchers at Wayne State University's Karmanos Cancer Institute.

The researchers reported in the journal Cancer Epidemiology Biomarkers & Prevention 2002 on a study of more than 9,000 women -- half with breast cancer -- designed to determine whether thyroid disorders or treatment of such disorders affects breast cancer risk.

"Only women with a history of thyroid cancer had an increased risk, but this was restricted to parous women (those who have given birth to at least one child)," the researchers reported.

"A history of any thyroid disorder was not associated with breast cancer risk," the researchers concluded. "We found no association between thyroid disorders or their associated treatments and the risk of breast cancer."

Other sources: Cancer Epidemiology Biomarkers & Prevention 2002