Existing Drugs May Protect Against Certain Cancers
Some show promise in preventing prostate, endometrial and breast cancers
SATURDAY, May 14, 2005 (HealthDay News) -- Some existing drugs, including statins, may be taking on a more important role in the prevention of different forms of cancer, new research suggests.
In several studies presented Saturday at the American Society of Clinical Oncology annual meeting in Orlando, Fla., existing medications were found to be of potential benefit in preventing the onset of prostate, endometrial and breast cancers.
For example, the hormone drug toremifene (brand name Acapodene) reduced the risk of developing prostate cancer by nearly half in men at high risk for the disease. Toremifene is a selective estrogen receptor modulator (SERM) currently used to treat advanced breast cancer.
"Prostate cancer is the most common cancer diagnosed in the U.S.," said study author Dr. David Price, director of urologic oncology and clinical research at Regional Urology LLC, in Shreveport, La. In the general population, men have a one-in-eight chance of being diagnosed with the disease in their lifetime, he said.
Men with a precancerous condition called prostatic intraepithelial neoplasia (PIN) -- the population analyzed in this study -- have a 15-fold greater risk of being diagnosed with prostate cancer.
In the study, 514 men with PIN were randomly assigned to receive 20 milligrams, 40 milligrams or 60 milligrams of toremifene or a placebo.
At the end of one year, 31.2 percent of the men in the placebo group had developed prostate cancer, vs. only 24.4 percent in the 20-milligram group. This is about equivalent to preventing 6.8 cancers per 100 patients treated every year, Price said.
Men receiving the higher doses of toremifene also had a lower incidence of prostate cancer but not a statistically significant one, Price said.
The drug was also safe and well tolerated, he added.
This is the first time a study has documented the natural history of PIN in a large prospective study, Price stated.
Further studies are under way to confirm the data, but "nevertheless it is promising," Price said. "I have good treatment options for prostate cancer but when I diagnose men with PIN, I tell them I don't have anything to offer, we just have to follow you closely. That generates a lot of anxiety. For the first time, we have some preliminary data that looks very promising."
Price also hopes to test the drug in other high-risk populations such as black men and men with a family history of the disease.
In another finding presented Saturday, the cholesterol-lowering drugs known as statins may reduce breast cancer risk by more than half. There is some data to indicate that statins suppress tumor growth in animals, but data in humans is conflicting.
This study, however, looked at existing data on about 40,000 female veterans. Women who took statins had a 51 percent lower risk for breast cancer than nonusers.
If statins do indeed work against tumor growth, it may be due to their ability to inhibit a particular enzyme that regulates different cell-signaling pathways, the study researchers suggested.
But the authors cautioned against over-interpreting the findings.
"Does that mean we should be giving statins to everyone? We are not ready for that yet," said Dr. Vikas Khurana, senior study author and assistant professor of medicine at Louisiana State University Health Sciences Center in Shreveport. "All we know is that statins are associated with a decreased risk for breast cancer. There could be another factor related to statin use that might be causing the effect. Regardless, this is one step further to a randomized trial that would give us an answer."
Yet a third study, this one a new analysis of patients taking the breast cancer drugs raloxifene and tamoxifen, found raloxifene may reduce the risk of endometrial cancer -- cancer of the uterine lining -- by 50 percent. Tamoxifen increased the risk, however.
Like tamoxifen, raloxifene is a selective estrogen receptor modulator (SERM). Unlike tamoxifen, raloxifene does not stimulate estrogen receptors in the lining of the uterus, the researchers said.
The apparent protective effect of raloxifene was most pronounced during the first three years of use, said lead investigator Dr. Angela DeMichele, an assistant professor of medicine at the Abramson Cancer Center and Center for Clinical Epidemiology and Biostatistics at the University of Pennsylvania.
For more on cancer prevention, visit the National Cancer Institute.