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A new study, reported in the Journal of the American Medical Association (June 4, 2008), suggests that lower levels of high-density lipoprotein (HDL; the "good" cholesterol), in and of itself, is not associated with an increased risk of heart disease.
Studies have linked low levels of HDL to an increased risk of ischemic heart disease. Whether HDL is a main factor in the development of heart disease, however, is unclear, due to other factors connected to low HDL cholesterol levels. The current study examined a group of patients with mutations in the ABCA1 gene causing reductions in HDL cholesterol levels but no increase in triglyceride levels.
The researchers concluded that mutations in ABCA1 are associated with "substantial, lifelong lowering of plasma levels of HDL cholesterol, but not with corresponding higher levels of plasma triglycerides or atherogenic [capable of producing a type of plaque in arteries] remnant lipoproteins, did not predict an increased risk of (heart disease)."
An effort to keep cholesterol down might also help men lower their levels of prostate-specific antigen (PSA)—a protein that can warn of prostate cancer. Using data collected on 1214 men taking statins, the researchers found that PSA levels were lower after starting the statins, and the reduction in PSA was relative to the drop in cholesterol.
The results of the study, presented recently at the annual meeting of the American Urological Association, validate a previous study that also indicated that lowering cholesterol reduced PSA. The researchers noted that, if confirmed, the findings of the new study would provide additional evidence that cholesterol plays a part in the biology of the prostate.
Murugesan Manoharan, MD, an associate professor of urology at the University of Miami Sylvester Comprehensive Cancer Center, who was not involved in the study, said it was not clear, however, whether reducing PSA with statins may actually conceal developing prostate cancer. He said that the current findings need further analysis. "Bringing down the PSA levels artificially does not mean necessarily the chance of developing prostate cancer," Dr. Manoharan said. "It might just bring the blood test reading down without reducing the risk of prostate cancer. In fact, we could miss the prostate cancer, because the PSA readings are on the lower side."
A major reduction in the rate of cancer was detected in patients who took statins that are soluble in fats, known as lipophilic statins. The researchers examined the association between lipophilic statin use and cancer incidence in >30,000 patients discharged from the hospital following treatment for a heart attack in the province of Quebec. The investigators linked the Quebec hospital discharge summary database to the drug claims database. The data indicated that 1099 individuals were hospitalized with a diagnosis of cancer during follow-up for up to 7 years.
Reporting in the American Journal of Medicine (April 2008), the researchers found that the overall rate of hospitalization for cancer was the equivalent of 13.9 cases per 1000 individuals per year among the high-dose statin group, compared with the rate of 17.2 and 20.6 cases per 1000 "person-years" among the low-dose statin patients and nonusers, respectively. In addition, the high-dose statin group had a 25% reduced risk of being diagnosed with cancer (and the low-dose statins group had an 11% lower risk), compared with patients who did not take statins.
"This is the first study to suggest a dose-response effect of lipophilic statins on cancer occurrence," said the researchers.
Individuals with high cholesterol and high blood pressure may be harming their eyesight. The 2 conditions appear to increase an individual's risk for retinal vein occlusion.
The findings were based on analysis of 21 previously published studies involving 2916 patients with retinal vein occlusion and 28,846 patients without the condition. The results, reported in the May 2008 issue of Archives of Ophthalmology, found that elevated cholesterol levels were >2 times as likely to be found in patients with retinal vein occlusion, compared with the control group. The results of the study also indicated that 63.6% of patients with the eye condition also had hypertension, compared with 36.2% of individuals without retinal vein occlusion. The authors concluded that physicians treating patients with hypertension, diabetes, and high cholesterol should be as concerned with the health of their patients' eyes as they are with the health of an individual's cardiovascular system.
F A S T F A C T: Low-density lipoprotein cholesterol levels of 130 to 150 mg/dL are considered borderline high.