MONDAY, April 26, 2004 (HealthDayNews) -- Not only do the cholesterol-lowering drugs called statins not increase the risk of breast cancer, there is some new evidence that they are associated with reducing the risk.
A study appearing April 26 in the online edition of Cancer found that postmenopausal women who used statins for more than five years had a lower risk of breast cancer.
"We wouldn't begin to recommend prescribing statins for cancer preventing, but the results are reassuring and encouraging," said Denise M. Boudreau, lead author of the study, which was her dissertation project at Fred Hutchinson Cancer Center in Seattle.
Millions of people in the United States are taking statins, which were approved by the U.S. Food and Drug Administration in 1987. Given that the drugs are so good at what they do, this trend is unlikely to let up.
There has been concern about their association with cancer, however, largely due to two studies. One reviewed the effect of all cholesterol-lowering drugs in mice and found an increased cancer risk. That result, however, is difficult to extrapolate to humans.
But in the mid-1990s, a randomized drug trial found that women taking statins had an increased risk of breast cancer compared to women taking a placebo. The trial had been designed to look at heart-related outcomes, however, and the number of women involved was not large.
Despite their limitations, the two studies provoked enough concern at the National Cancer Institute to prompt it to ask Boudreau to research the matter.
Boudreau and her colleagues analyzed data on 975 women aged 65 to 79 who had breast cancer, and 1,007 women without the disease. The women were all residents of western Washington state and gave information about statin use, their medical history and health behaviors during an in-person interview.
There was no increased risk of breast cancer among women currently using statins. Among women who had been using the drugs for more than five years, the risk actually went down by as much as 30 percent.
Although the study was an observational one, not the gold-standard randomized variety, Boudreau said, "I believe we can be confident about what's going on. It's too early to draw a conclusion, but I think they're encouraging results and reassuring, and they are supported by laboratory data that show that statins do, through a variety of mechanisms, decrease cancer risk."
Dr. Paul Tartter, a senior surgeon at St. Luke's-Roosevelt Hospital Cancer Center in New York City, said the results are exactly what he would have predicted. His frustration, however, is that the researchers didn't measure blood cholesterol levels, which is what could be the link to cancer in the first place.
"I think it's the cholesterol that is the issue. There was some research that women with high cholesterol were at a higher risk of breast cancer," Tartter said. "Also, women with breast cancer who have high cholesterol levels do worse than women with breast cancer who have normal cholesterol levels."
For her part, Boudreau is going to continue researching the topic from her new position at Group Health Cooperative in Seattle. "We're going to do a much larger, more detailed study looking at statins and their link to breast cancer and also other forms of cancer," she said. "It's still observational, but it will improve on some of the previous methods and it will be in a very large population. We actually will have data on 90,000 women." The results should be available in about a year and a half, she added.