Sunday, March 27, 2011

Does a Lipitor a Day Keep Prostate Cancer Away?

Millions of people worldwide are taking cholesterol lowering medicines called Statins.  You may know these drugs by some common brand names like Lipitor or Crestor.  The importance of these medicines in preventing and treating heart disease cannot be overstated and has been demonstrated in multiple excellent clinical studies.  With the widespread use of Statins all over the world, many studies have been conducted which have analyzed other potential benefits of these medications.  One particular area of interest has been the potential use of Statins to battle cancer.  Statins have been studied in relation to many malignancies but one particular cancer for which Statins have gotten a lot of attention is prostate cancer.

At first glance it may seem pretty strange that a drug made for lowering cholesterol would have any impact on prostate cancer.  However, if you take a deeper look at the risk factors for prostate cancer you will start to see the connection.  Prostate cancer has always been associated with fat.  Studies have repeatedly demonstrated that overweight men are at higher risk to develop prostate cancer, particularly more aggressive types.  Animal and human studies have demonstrated that high fat and high calorie diets can fuel the fire for the growth of existing prostate cancer.  In addition, exercise and weight loss have been shown to have beneficial effects for those with prostate cancer.  Looking at this strong association between fat and prostate cancer, it is not surprising that drugs like Statins may have a role in combatting it.

But how do Statins actually fight prostate cancer?  Nobody really knows but research has come up with several possibilities.  Some mechanisms appear to involve the known cholesterol lowering function of these drugs while others have nothing to do with cholesterol at all.  Studies have theorized that Statins may keep prostate cancer cells from dividing, prevent them from spreading, or limit them from reaching new blood supplies.

Theories are great for academic discussions but how do Statins actually stack up in clinical practice?  Most studies evaluating Statins and prostate cancer have focused on the prevention of prostate cancer.  These studies have all been fairly similar in that they evaluated thousands of men and were observational.  An observational study is one in which people are simply monitored over time with questionnaires or interviews. There is no real control over what doctors or patients are doing. The results of these studies have been variable.  For every study that has shown that Statins decrease the risk of prostate cancer another demonstrates no effect.   Still others have actually shown an increased risk of prostate cancer in men taking Statins.  To make things more complicated, some studies demonstrated benefits of Statins only for men who also took Aspirin (another drug that has potential as a cancer fighter).  Despite all of these conflicting findings, one encouraging trend that seems to appear in a great deal of these studies is that Statins appear to decrease AGGRESSIVE  prostate cancer even if they did not have an impact on prostate cancer prevention as a whole.  That benefit, alone, may be extremely important.

The results of these studies need to be taken with a grain of salt.  As I mentioned, they were mostly observational so they did not control for many factors like whether the subjects of the study took the drugs the whole time and how thoroughly the subjects were screened for prostate cancer.  As a result, even if the studies had demonstrated an overwhelming effect, the limitations of the studies would still leave their findings at least a little in doubt. 

Other studies (also with significant imitations) have looked at the effects of Statins in limiting the recurrence of prostate cancer after treatment with surgery and radiation therapy.  Like in the previous studies, the results were mixed.  Also like the previous studies, however, a trend signaling  a greater effect of the Statins on higher grade prostate cancer was noted. 

So what do we take from all of these findings?  First, we have to be careful when he hear about studies in the news claiming substantial benefits of a drug.  Evaluating medical studies is a lot like reviewing credit card offers: you have to read the fine print!  Second, we see that Statins COULD potentially be beneficial in helping to prevent and treat prostate cancer, particularly aggressive prostate cancer.  The good news is that many men diagnosed with and at risk for prostate cancer are already taking Statins for high cholesterol.  The real question is whether men who do not otherwise need Statins should be given these drugs solely for its potential benefits in the fight against prostate cancer?  At this point, that indication, by itself , is not easy to support.  Although widely taken without problems, Statins do have side effects.  Potential adverse effects include liver damage, muscle pain and damage, gastrointestinal side effects, and rashes.  Although these problems do not happen often, they DO happen.  As a result, it is hard to unquestionably recommend these medicines solely for prostate cancer prevention when the proof of their efficacy for this is not overwhelming.  Pending better, randomized and controlled studies, the jury is still out about Statins and prostate cancer.

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