Lipid Drugs May Cut Breast Cancer Risk
Statins and Other Cholesterol-Lowering Drugs Lower Risk by 68% in Older Women
Oct. 16, 2003 -- New research shows cholesterol-lowering drugs proven to reduce the risk of heart disease may also help older women reduce the risks of breast cancer.
The new study shows that those who say they take statins or other types of cholesterol-lowering drugs have a 68% lower risk of breast cancer after seven years of study compared with those who don't take these drugs.
Interestingly, this new finding in the October issue of the Journal of Women's Health involves the same patients who two years ago, in an earlier phase of this ongoing study, had a lower risk of breast cancer only after taking the popular statin drugs that include Lipitor, Mevacor, and Zocor. At that time, other types of cholesterol-lowering drugs didn't appear to protect them.
"In the initial phase, which I presented before the American Society for Clinical Oncology a couple of years ago, we didn't find a strong effect with other lipid-lowering drugs -- only the statins," researcher Jane Cauley, DrPH, of the University of Pittsburgh, tells WebMD. "But that was a preliminary report. With a longer follow-up period, at seven years, we also found a benefit from the other agents [cholesterol lowering drugs]."
They include doctor-prescribed Abitrate, Colestid, Lopid, and niacin, as well as fish oil capsules available over-the-counter. However, her study didn't investigate which individual drug seemed to offer the most benefit or how long the women took them. In this report, statins offered only slightly more protection than the other products.
Cauley's study involved 7,500 white women in four cities, with an average age of 77 -- a high-risk group for breast cancer. Those who reported regularly taking cholesterol-lowering drugs had similar body weights, exercise patterns, and other risk factors for breast cancer as those not taking the drugs.
Exactly why cholesterol-lowering drugs seem to lower cancer risk is a mystery, but researchers have long known that cholesterol inhibition somehow stunts tumor cell growth. At this year's American Society of Clinical Oncology meeting, Dutch researchers told of their study finding that people who took statins for at least four years cut their cancer risk by 36% -- with the most protection against prostate and kidney cancers.
Statins, a type of cholesterol-lowering drug, have been more closely studied for having a possible role in cancer prevention than the other cholesterol-lowering drugs in Cauley's research. Research is now underway to determine if these pills reduce oxidative stress that boosts cancer risk, or activate an enzyme system important in cell development, she says.
But specifically to breast cancer, cholesterol-lowering drugs may affect the way estrogen is metabolized, says Cauley. Cholesterol is one of the main sources of estrogen -- and high estrogen levels can promote breast cancer.
"At this point, we don't know for sure, but there are several plausible biological mechanisms."