Statins and Cancer Prevention: Fact Sheet
Untitled Document
Key Points
- What are statins?
Statins are a type of drug taken by millions of Americans to lower cholesterol.
This class of drugs works by blocking an enzyme known as HMG-CoA (3-hydroxy-3-methyglutaryl
COA) reductase, which the body needs to make cholesterol. Statins help to
treat and prevent heart disease by lowering blood cholesterol. In the United
States, statins available by prescription
include atorvastatin
(Lipitor™),
lovastatin (Mevacor™),
pravastatin
(Pravachol™),
and simvastatin (Zocor™). In the United States, statins are
available by prescription only.
- Can statins prevent cancer?
Animal research and ongoing observation of people who take statins suggest
that these drugs may lower the risk of certain cancers, including colorectal
and skin cancers. Statins' known benefits in preventing cardiovascular disease,
along with years of strong evidence that these agents are relatively safe,
have led researchers to explore whether statins have the potential to prevent
cancer. People should not take statins for cancer prevention
outside of a clinical trial.
- Why do scientists think statins might prevent
cancer?
By exploring the effects of statins on the process of cancer at the molecular
level, researchers have found that statins work against critical cellular
functions that may help control tumor initiation, tumor growth, and metastasis.
Specifically, statins reduce (or block) the activity of the enzyme HMG-CoA
reductase and thereby reduce the levels of mevalonate and its associated
products. The mevalonate pathway plays a role in cell
membrane
integrity, cell signaling, protein
synthesis, and cell
cycle progression, all of which are potential areas of intervention
to arrest the cancer process.
- What are the common side
effects of statins?
Although generally well-tolerated, statins have been associated with muscle
pain (myopathy) and liver
toxicity
(hepatotoxicity). People who take statins should be monitored by their health
care providers for these reasons.
- Is the National Cancer Institute (NCI) supporting
research testing whether statins might prevent colorectal cancer?
NCI's Cancer Prevention Clinical Trials Consortia is developing a trial
for people at increased risk for colorectal cancer who also have been found
to have aberrant
crypt foci (ACF).
ACF are clusters of abnormal
cells in the lining of the colon and rectum that have been associated with
the development of colorectal tumors. Using existing technology, ACF represent
the earliest stage
of detectable risk for colorectal cancer.
This NCI-sponsored phase
II trial will begin patient enrollment in late 2005 or early 2006. The
study will assess the efficacy
of atorvastatin (and two other investigational
agents, an anti-inflammatory,
sulindac,
and another compound
that promotes the growth of healthy bacteria
in the colon) against ACF. Paul Limburg, M.D., a researcher in gastroenterology
at the Mayo Clinic (Rochester, Minn.), will be leading this multicenter
effort.
- What evidence is there that statins may have an
effect on colorectal cancer?
Studies have shown that statins inhibit the growth of colon cancer cells
grown in the laboratory. Consistent preventive effects of certain statins
against colon cancer were first described in cancer studies in rodents published
in 1994.
Some human observational
studies have since suggested that statins may have protective effects
against colorectal cancer. Most recently, researchers from the University
of Michigan, collaborating with researchers in Israel, compared the use
of statins among 1,953 patients who were diagnosed
with colorectal cancer and 2,015 other people who did not have the disease.
This study specifically associated a 47 percent reduction in the risk of
colorectal cancer with statin use (as opposed to the use of another type
of lipid-lowering drug, fibrates). [Statins and the risk of colorectal cancer.
Poynter, JN., et al. New England Journal of Medicine, May 26, 2005,
(352:2184–92].
- Is NCI supporting research with statins to prevent
other types of cancer?
NCI is developing a phase II placebo-controlled trial to evaluate whether
lovastatin can reverse precancerous
changes in atypical (so-called dysplastic) nevi, a precursor to melanoma
skin cancer, and thus have the potential to prevent progression to melanoma.
Ken Linden, M.D., Ph.D., a researcher in dermatology at the University of
California, Irvine, will be leading this multicenter effort. The study will
begin patient enrollment in late 2005 or early 2006.
- What evidence is there that lipid-lowering drugs
can prevent skin cancer?
Two large cardiovascular clinical trials have demonstrated a significant
reduction in skin cancer among patients taking lipid-lowering drugs. Although
clinical data do not consistently show a decreased risk of skin cancer with
statin use, various human trials and preclinical
studies suggest that statins may have chemopreventive
activity against skin cancer.
- Where can I get more information?
For more information about cancer, visit the NCI Web site at http://www.cancer.gov
or call NCI's Cancer Information Service at 1–800–4–CANCER
(1–800–422–6237).
Information on cancer prevention is available at the NCI Division of Cancer
Prevention Web site at http://prevention.cancer.gov
on the Internet.
More information on cholesterol-lowering drugs can be obtained from the
FDA
Web site at http://www.fda.gov on the Internet.
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