An article published in the December 2013 issue of the journal, Science, done on one million people over 14 years found an association between having high cholesterol and the incidence of breast cancer. The risk of breast cancer was increased 1.64 times.
While this sounds impressive, when you take a careful look, it is interesting but far from proven that using statins would change the incidence of breast cancer in those with elevated lipids. What is needed is a prospective study where a large group of similar women with high lipids is divided into two groups. One group would be followed over a decade and not treated and the other group would be treated with a statin. In this case the incidence of breast cancer could be compared and an answer determined.
Unfortunately, this study will be referenced by many physicians who will be more inclined to use statins, especially in women, because the premature data published raises the question that statins might lower the risk for developing breast cancer in one subgroup of breast cancer types (estrogen positive).