Too Low LDL-Cholesterol Levels?

Robert W. Griffith, MD

It was Wallace Simpson, Duchess of Windsor, who said: "A woman can't be too rich or too thin". And we've been saying for years "You can't have an LDL-cholesterol that's too low". Well, maybe you can, according to a report in the Journal of the American College of Cardiology.

Tufts scientists analyzed large, randomized statin trials, to assess the benefits and possible adverse effects of the drugs. The 23 studies covered 310,000 person-years of follow-up during which adverse events were collected.

Overall, as known already, statins lowered LDL-cholesterol levels and reduced cardiovascular risk. The risks of liver enzyme elevations and muscle damage ( rhabdomyolysis) were related to the dose of statin used, not the LDL-cholesterol changes achieved. This finding, too, was largely expected. However, a new finding from the analysis brought a surprise. The investigators found a clear relationship between the achieved LDL-cholesterol levels and the risk of new cancer cases. (Note that it was the actual low LDL-cholesterol levels, not the percentage reduction or the actual size of the reduction that carried the increased cancer risk.)

Cancer cases were reported in only 13 of the 23 studies in the analysis, but this was a large enough collective to allow a statistically significant effect to be shown. The new cancers were not of any specific type or location. The authors of the analysis (and the largest statin manufacturer) have said the finding should only be "hypothesis generating" - i.e. it requires confirmation in further studies before being considered cause-and-effect.

In fact, several papers published decades ago - long before statins - describe the heightened risk for cancer in people with low cholesterol levels. Even if the risk of cancer is found to be increased with statin use, the benefits of cholesterol-lowering are great, and would need to be balanced against the possibly slight increase in cancer risk. Let's wait and see what comes next. For instance, a new publication in Circulation describes how useful statins are in people with very low LDL-cholesterol levels - even below 40 mg/dL.

Source
HealthandAge Blog

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