Prostate cancer is the sixth most common cancer in the world and the second leading cause of cancer death in American men. Almost a quarter of a million new cases are diagnosed annually and the lifetime risk for a man to develop prostate cancer is one in six. It is a well known phenomenon that cholesterol and fatty deposits accumulate in solid tumors such as prostate cancer. Furthermore, very advanced cancer such as metastatic disease can lower circulating cholesterol levels. There is growing evidence that a link between high cholesterol and prostate cancer exists and that cholesterol may promote the growth of tumors.
Most of the evidence linking high cholesterol and prostate cancer has been based on observational studies. Recent studies suggest that not only does high cholesterol seem to increase the risk of developing prostate cancer but that high cholesterol may make existing prostate cancer more aggressive. One simple hypothesis to explain this link is that high cholesterol promotes the production of androgens, hormones that promote the growth of prostate cancer. Other more complicated explanations involve cholesterol within prostate cancer cells directly affecting cancer cells thereby stimulating their growth.
Given the above observations, a 2007 study was published that explored the causes of the falling death rates from prostate cancer. One interesting observation that was reported was that men who had higher levels of cholesterol tended to have lower prostate cancer death rates. No, that’s not a typo even though it seems to be the exact opposite of what I just wrote in the previous paragraph. The authors of this study believe that men with higher cholesterol levels had lower prostate cancer death rates because they were taking statins.
It turns that out that statins, the wonder drug of the modern era, not only lower cholesterol and decrease risk of heart attack and stroke but also can kill prostate cancer cells. This effect has been demonstrated in laboratory studies on cancer cells and now there is more evidence showing this effect in humans. In fact, at the April 2008 Annual Scientific Meeting of the American Urological Association, data was presented that showed that statins lower not only LDL but also PSA (prostate specific antigen), a blood tumor marker for prostate cancer. And, the decline in PSA was proportional to the decline in cholesterol.
Not surprisingly, there are now numerous ongoing studies looking at how exactly statins kill not only prostate cancer but also various other cancers as well and whether this can translate into an overall benefit in survival. One concern raised was the possibility that lowering PSA with a statin may mask an underlying cancer and not necessarily be helpful overall. In the meantime, we should remember that cholesterol and PSA levels can be valuable indicators in the detection and treatment of disease and that we should continue to monitor them closely.