Higher HDL cholesterol lowers cancer risk – Use Niacin?

Researchers from Tufts University School of Medicine – Boston, MA, have announced a significant inverse relationship exists between elevated HDL levels and cancer risk.  This new analysis, reported in the June 14th, 2010 issue of the Journal of the American College of Cardiology, demonstrates a 36% reduction in the risk of developing cancer, for every 10mg/dl increase in HDL levels[1].

The researchers performed a meta-analysis of all lipid-intervention clinical trials, and included those which met criteria for size and duration, and that also recorded baseline HDL levels and cancer incidence.  They identified 24 clinical trials with more than 625,000 person-years of follow-up.  Among them, were 4S, WOSCOPS, CARE, GISSI, ALLHAT-LLT, CORONA, and JUPITER.  In the univariate random-effects meta-regression analysis, there was a significant 28% reduction in cancer risk for every 10mg/dl increase in baseline HDL levels.  In a model that controlled for other variables, including LDL levels, age, body-mass index, sex, and smoking status, there was a more significant, 36% lower risk of cancer for every 10-mg/dl increase in HDL.

While this analysis strongly identifies an association between low levels of HDL and increased cancer risk, there are no randomized controlled trials confirming that the use of niacin to raise HDL would result in lower cancer rate.  There is evidence to support this notion however.  There has long been an understanding that HDL has important anti-inflammatory and immune function roles, and that low levels of HDL are a marker for an overall increased risk of chronic disease[2]. Indeed, the role of HDL to remove excess LDL cholesterol from the arteries may not even be its most important role. This was suggested at the May, 2010 National Lipid Association’s Annual Sessions in Chicago.

Presentations at this symposium of cholesterol experts discussed that not all HDL is “functional” HDL, and not every HDL intervention elevates “functional” HDL.  Dr Bella Asztallos, a lipid metabolism researcher also from Tufts University, presented data that demonstrated niacin was far superior at raising α-1 HDL (HDL2), the most functional class of HDL particles, by 200%, and lowered preβ-1 HDL, a dysfunctional HDL, by about 30%[3].  This compared to fibrates, a class of drug which raises HDL-C by 4-10%, which slightly decrease the a-1 HDL subclass.

For now, there is solid evidence from randomized clinical trials that niacin is the most effective “HDL-raising” therapy, reduces atherosclerosis, and decreases the incidence of cardiovascular outcomes and mortality.  These data make a strong case that increasing HDL with niacin may confer other substantial health benefits as well. Levels of HDL that are associated with increased risk are below 50mg/dl for women, and 40 mg/dl for men, and according to consensus guidelines, are secondary goals of treatment after LDL reduction[4].