Further study needed to determine if drugs prevent prostate cancer
Men who take even small amounts of common cholesterol-lowering drugs such as Lovastatin and Simvastatin have a significantly reduced risk of prostate cancer, according to a new study by Oregon Health & Science University Cancer Institute researchers.
"If these results are confirmed in a larger prospective study, they may provide necessary evidence to consider the use of cholesterol-lowering drugs in prostate cancer prevention. Currently, no preventive measures are available for prostate cancer," said Jackilen Shannon, Ph.D., R.D., assistant professor of public health and preventive medicine in the OHSU School of Medicine, member of the OHSU Cancer Institute and lead author of the study.
Shannon's research suggests that men who have taken any amount of these drugs, known as statins, have a 58 percent lower risk of prostate cancer than men who have taken none at all. Shannon presented study results at the American Society for Clinical Oncology annual meeting in New Orleans, La., on June 6, 2004.
"We were interested in the relationship between statin use and prostate cancer because recent research has demonstrated that in a number of tumor types, statins also induce cancer cell death and growth arrest," Shannon said.
Shannon and colleagues evaluated the association between statin use and prostate cancer risk in a population of older veterans enrolled in a case-control study of diet and prostate cancer risk.
"Our data suggest statins may also impact PSA production," Shannon said. In addition to being associated with a reduced risk of prostate cancer, statins were associated with a 55 percent lower risk of an elevated prostate-specific antigen (PSA) level. Certain prostate conditions, including prostate cancer, can cause high levels of PSA in the blood. PSA levels are monitored to help predict the presence and progression of prostate cancer.
In a retrospective study, researchers reviewed records of men who were referred to a Veterans Affairs Medical Center for a prostate biopsy. Cases reviewed for this study include those of 72 men diagnosed with prostate cancer, 150 who had negative biopsies, and 208 whose PSAs were normal. Data on their statin use was pulled from the Veterans Affairs' electronic pharmacy database.
"Because the cases reviewed were part of a larger study of diet and prostate cancer risk that included extensive diet questionnaires, we were able to adjust our statin study data for many different factors, including cholesterol in the diet, and total fat and calorie intake," Shannon said. Data also was adjusted for age, body mass index and race.
Statin prescriptions from 1997 to biopsy date were recorded. Data included date of initial prescription, date prescription discontinued or date of new prescription, daily dose and number of pills. The four most commonly used brands of statins were reviewed, including Lovastatin, Simvastatin, Fluvastatin and Atorvastatin. Researchers analyzed total days each statin was used at each prescribed does, cumulative dose of individual statins, average daily dose and total statin use. Statin data was merged with demographic data from the main case-control study.
"The VA's electronic pharmacy provided a rich set of detailed data that allowed us to more accurately characterize the association between statins and prostate cancer risk," Shannon said. "This data led us to unique findings about average daily statin dose and cumulative dose."
When statin use was grouped by duration and dose, those with a cumulative dose of more than 19 grams had lower risk of prostate cancer. Those with an average daily dose of more than 40 milligrams were at a lower risk of an elevated PSA as compared to subjects with an average daily dose below 40 milligrams. These results remained consistent when individual types of statins were analyzed separately.
"While these data are suggestive, this is a pilot study limited by a small sample size and lack of control for additional comorbid factors," Shannon said. "Further investigation is warranted."
Prostate cancer is the most common cancer in men and the second leading cause of cancer-related death in American men. Overall, one in six men will develop prostate cancer during his lifetime.
This research was conducted as part of a study funded by the National Cancer Institute, a component of the National Institutes of Health.
Particulars: ASCO Abstract No. 4596, Statin use and prostate cancer risk