Women who use statin drugs to lower their cholesterol are no more likely to develop breast cancer than women who do not use the drugs, U.S. researchers reported on Tuesday.

The study, published in the Journal of the National Cancer Institute, contradicts some earlier studies that suggested there may be a link. But it offered the possibility that certain formulations of statin drugs may reduce breast cancer risk.

Statins are among the most widely prescribed drugs in the United States, with $12.5 billion in annual sales and tens of millions of patients.

“Because breast cancer is the most frequent cancer in U.S. women, any link between statin use and breast cancer risk would have major public health implications,” the researchers wrote.

The researchers, from universities across the United States, studied the medical records of more that 156,000 women past menopause taking part in the giant Women’s Health Initiative study. About 7.5 percent of the women in the study used statins.

Over the more than six years of the study, about 4,300 women were diagnosed with breast cancer.

There was not a significant difference among the women who took statins and those who did not, the researchers, led by Dr. Jane Cauley of the University of Pittsburgh, reported.

But women who used a certain type of statin, known as hydrophobic statins, had an 18 percent lower risk of breast cancer. This should be studied further, the researchers said.

“At minimum, our findings suggest that women can now be reassured that they are not increasing their risk of developing breast cancer by taking these drugs,” Cauley said in a statement.

“Although we found that women who took hydrophobic statins actually lowered their breast cancer risk, we believe this finding needs to be confirmed in additional studies.”