The recent trend over the past few years in the management of cholesterol has been to be more aggressive. Initially, the American Heart Association recommended that those people who have had a heart attack, for example, should have LDL levels of less than 100mg/dl. Studies further suggested that lowering your LDL to less than 70mg/dl was more beneficial and this has now become a common goal for heart attack survivors. Some physicians and scientists believe that we should go even further by shooting for an LDL level less than 50mg/dl! Clearly, these goals cannot be attained through diet and exercise alone and thus the judicious use of cholesterol lowering medicines such as statins has been strongly advocated. Knowing that all cholesterol seems to be important for normal body function including the "bad" LDL, some began to wonder whether going too low on LDL and cholesterol was not a good thing. In fact, an association between cancer and lower cholesterol levels has been observed since the early 1990s, yet no causal relationship has been proven as of yet. It appears that a total cholesterol level less than 160mg/dl is associated with an increased cancer risk. Last year, researchers began to see some scientific evidence of this relationship with regards to statin use.
In 2007, a study was published in the Journal of the American College of Cardiology that investigated whether lower LDL levels induced by statins were related to an increase risk of liver and muscle damage. The conclusion of this study which examined over 75,000 patients concluded that the dose of the statin and not the level of LDL lowering was mainly responsible for an increase risk of liver and muscle damage. In their analysis, another disturbing trend was noted. Those people who had lower LDL levels were also observed to have an increased risk of a new diagnosis of cancer. The authors were quite clear in stating in their conclusions that this association did not prove a causal relationship between low cholesterol or statin use with cancer development. Nonetheless, a red flag was raised.
Last week, the same authors reported their observations looking at statin, LDL levels, and cancer risk. They compared ~50,000 people on active statin therapy with ~45,000 not on statin therapy and compared their risk of cancer with their LDL levels. In short, the results were somewhat relieving. Again, the same trend of lower LDL levels and increased cancer risk was observed. But, there was not an increased risk for those people taking statins. Thus it would seem that statins themselves do not promote cancer.
Still, this disturbing trend of lower LDL levels and increased cancer risk remains. The question we all want to answer is whether or not low LDL and cholesterol cause cancer or rather is a sign of another underlying disease process. Some argue that low LDL levels are a subtle manifestation of a precancerous condition that eventually leads to full blown cancer. These people may have poor inflammatory and immune responses that may be of benefit in preventing the development of heart disease but may allow cancer cells to take hold. After all, our immune systems not only fight off infection but also remove cells that are precursors to cancer. Others argue that low LDL levels themselves may promote cancer cell formation and growth by altering cell genes. At this time, no one knows for sure which is the case.
Given this uncertainty of cause or effect of cholesterol and cancer but the certainty of high cholesterol leading to more heart disease, lowering cholesterol and LDL to appropriate levels is still recommended. The wealth of data supporting this positive relationship of lower cholesterol and lower heart attack risk far outweighs the unclear relationship of lower cholesterol and increased cancer risk. Still, we need remember that a relationship does exist especially since the FDA just announced it is investigating whether Vytorin (simvastatin and ezetimibe) is associated with an increased cancer risk.
Published On: September 05, 2008