Statin drugs are a group of widely prescribed ones used to lower a person's cholesterol level. Common statin medications include brands such as Lipitor, Crestor and Zocar. Statins work by inhibiting an enzyme in the human body, 'HMG-CoA reductase,' which is used to manufacture cholesterol and the drugs may also help to clear already formed cholesterol from the bloodstream. High cholesterol is a known cause of cardiovascular disease and it is well-established that statins reduce the rate of illness and death caused by cardiovascular disease. While statins can help to prevent the risk of a stroke or heart attack, some studies have also suggested that statins might have an effect on prostate cancer.
Statin - (HMG-CoA reductase inhibitors) - A class of drugs used to lower cholesterol levels by inhibiting the enzyme HMG-CoA reductase, which plays a central role in the production of cholesterol in the liver, which produces about 70% of total cholesterol in the body. Increased cholesterol levels have been associated with cardiovascular disease (CVD). Statins have been found to prevent cardiovascular disease in those who are at high risk. A number of statins are on the market including:
Prostate Cancer - Also known as carcinoma of the prostate, is the development of cancer in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, some grow relatively fast. The cancer cells may spread from the prostate to other parts of the body, particularly the bones and lymph nodes. It may initially cause no symptoms. In later stages it can cause difficulty urinating, blood in the urine, or pain in the pelvis, back or when urinating.
Whether the effect would be harmful or beneficial has been the subject of studies for quite some time. When statins first became widely available to people in the 1980's, concerns arose that these medications may spur some cancers. Those fears have been largely dispelled and a huge meta-analysis of 135 randomized studies that included more than a quarter of a million study participants found that use of statin medications did not increase the risk of developing a form of cancer.
Whether or not statins had a positive impact on cancer; however, remained an open question. Research has suggested that statins may slow cancer cell growth in certain forms of cancer such as colorectal, breast, or skin cancers and might lower the risk for colorectal and skin cancers. Some research has also suggested that statins may lower the overall risk for prostate cancer, yet because of inconsistent findings it was plain more research was needed. From ongoing research, what is emerging is that statins might indeed reduce the risk of death from prostate cancer, but likely have little effect on whether or not a man develops prostate cancer to begin with.
Dr. Elizabeth Platz of Johns Hopkins Bloomberg School of Public Health is a researcher of prostate cancer. Dr. Platz and her colleagues have twice discovered that people with lower levels of cholesterol had a lower risk of developing more aggressive disease as defined by high Gleason scores. The discovery is another reason for men to bypass a plate of fried chicken and visit the salad bar instead. Doing so naturally lowers their cholesterol levels.
Research from Canada, published in the Journal of Clinical Oncology, discovered that men who used statins after receiving a diagnosis of prostate cancer had a 24% decreased risk of death from the disease when compared to those who did not take statin medications. The longer the men took statins, the greater the protective effect. For example; men who took statin medications for less than a year after being diagnosed had a 1% lower risk of death from prostate cancer compared to those who did not take statins. Yet men who had taken statins for three or more years after diagnosis decreased their risk of death from cancer by 39%.
Notably, the study also discovered that statin use before a diagnosis of prostate cancer was even more protective to men in terms of both mortality due to prostate cancer, or from any other cause. Pre-diagnostic statin use cut men's risk of death from prostate cancer by 45% and bestowed a 34% reduction of the risk of death from any cause when compared to men not taking statin medications. All the men involved in the study had been newly diagnosed with non-metastatic prostate cancer at the time they enrolled. Men who used statins after their diagnosis were 23% less likely to develop distant metastatic cancer spread during the study.
The study adds to additional research showing reduced prostate cancer-specific mortality among men who used statins. Dr. Janet Stanford of the Fred Hutchinson Cancer Research Center in Seattle and her colleagues published a study demonstrating that men who took statins before their diagnosis of prostate cancer experienced an 81% reduction of prostate cancer-specific mortality when compared with men who did not take statins. At a ten year follow-up, 1% of statin users had succumbed to prostate cancer compared to 5% of non-users. The study; however, also found that statin use before a diagnosis of prostate cancer diagnosis did not affect whether or not prostate cancer progressed or recurred. At the time the study was published, Stanford called for confirmation of the study to validate its findings and suggested that the research might pave the way for a large and randomized, placebo-controlled study that will present the most definitive results on whether or not men with prostate cancer should or should not be prescribed statins to decrease their risk of death from the disease.
The Canadian study was a particularly good one for several reasons. It is one of the bigger studies with the ability to study lethal cancer during the follow-up period. Due to the fact that smaller studies might pick up outcomes that occurred simply by chance instead of being due to the effect of the drug, the study permitted much more confidence in the findings that statin use did have a positive effect on the risk of dying from prostate cancer. A unique feature of the study is that the researchers examined statin use both before and after diagnosis.
The distinction may be important in helping to determine the mechanism of action statins have on prostate cancer. According to one doctor involved, where statin use after diagnosis is concerned - the drug will most likely influence tumor cells after they have left the prostate, although statin use before diagnosis might influence the tumor itself. Knowing when and where statins act on prostate cancer may help to determine which people are most likely to benefit, as well as lead to the development of new drugs specific to prostate cancer after the cellular pathways of action have been determined.
Researchers are now working out how statins may affect genes and additional molecular pathways for better or worse in men with prostate cancer. The researchers will examine prostate tissue samples from men who have just undergone radical prostatectomy. The researchers desire is to determine if there are differences in gene expression between men who use statins and men who do not.
Even though statin use may have an effect on survivability of prostate cancer in some men, the evidence does not point to a protective effect from the drug in terms of overall risk of prostate cancer. The study by Dr. Platz and colleagues found that while risk of lethal disease was lowered in statin users, there was no reduction in risk for the overall occurrence of prostate cancer in men taking statin medications. Dr. Platz and colleagues decided to further investigate overall risk of prostate cancer and statin use.
Dr. Platz stated, "Most of overall prostate cancer is early stage disease, and we did not see an association between statin use and prostate cancer overall We were worried maybe we might be missing an association because of a particular study bias detection bias." Men who regularly pursue care through their primary care doctor are more likely to be screened for PSA and cholesterol levels. If a man has high cholesterol and PSA levels, a doctor may recommend a biopsy. Regular screening can lead to both a high incidence of statin use and prostate biopsy. Due to the fact that biopsy is quite sensitive to picking up early prostate cancer, this may create a false association between statin use and prostate cancer. Dr. Platz said, "We wanted to study early prostate cancer in a setting where such detection bias is very unlikely to be operating."
Dr. Platz says that overall, if you take all of the literature together, it appears as though statin drugs may inversely associated with aggressive disease, meaning the cancer progresses to the point of distant metastatic spread, or death of the person; yet not associated with the development of the most common form of prostate cancer in men, which is very early disease.
Plainly, the pursuit needs to be understood much better, yet there are a number of likely avenues of action statins may exert on cancer cells. Pre-clinical research has shown that these cholesterol lowering medications may inhibit prostate cancer cell growth and might encourage cancer cell death and prevent tumor blood vessel growth, as well as modulate immune system factors. In addition, it has been suggested that statins might tamp down the activity of certain, 'oncoproteins.' Dr. Platz and colleagues have not twice found, in two different studies of men, that people with lower levels of cholesterol experienced a lower risk for developing more aggressive disease.