A pair of studies in Cancer Epidemiology, Biomarkers & Prevention, lay to rest the decades-long concern that lower total cholesterol may lead to cancer, and in fact lower cholesterol may reduce the risk of high-grade prostate cancer.
Demetrius Albanes, M.D., a senior investigator at the National Cancer Institute, said early studies suggested that low cholesterol could increase the risk of certain types of cancer.
"Our study affirms that lower total cholesterol may be caused by undiagnosed cancer. In terms of public health message, we found that higher levels of 'good cholesterol' (HDL) seem to be protective for all cancers, which is in line with recommendations for cardiovascular health," said Albanes.
The researchers observed 29,093 men from the Alpha-Tocopheral, Beta-Carotene Cancer Prevention Study cohort for 18 years, making it the largest and longest study of its kind. In that follow-up period, they noted 7,545 cancer cases. Low total cholesterol blood levels were associated with an 18 percent higher risk of cancer overall, similar to the increases seen in previous studies, but this risk disappeared when the researchers excluded cases that occurred in the early years after the original blood draw.
This finding suggests that the low total cholesterol levels did not cause cancer, but rather were the result of underlying cancer, said Albanes. Higher levels of HDL cholesterol were associated with a 14 percent decreased risk of cancer even after excluding nine years of early cases.
In an accompanying study that looked specifically at risk for high-grade prostate cancer, Elizabeth Platz, Sc.D., M.P.H., associate professor in the Department of Epidemiology at the Johns Hopkins Bloomberg School of Public Health and co-director of the Cancer Prevention and Control Program at the Sidney Kimmel Comprehensive Cancer Center at the Johns Hopkins University, found a link between low cholesterol and decreased risk of high-grade prostate cancer among 5,586 men older than 55 years.
Specifically, if men had total cholesterol of less than 200 mg/dL they had a 59 percent reduced risk of high-grade prostate cancer, defined as a Gleason score eight to 10. No association was seen for prostate cancer overall or for prostate cancer with a lower Gleason score. Platz said that the study supports another benefit of keeping cholesterol low among men in this age group.
"High-grade prostate cancer is less common than prostate cancer overall, but it is a subset of prostate cancer that is more likely to progress," said Platz.
Discussion of the benefits of lower cholesterol inevitably leads to the discussion of the role of statins, which have produced one of the great public health success stories of the past few decades as cholesterol and, subsequently, heart disease rates have both fallen. Statins have been enormous money makers for their industry manufacturers and with two already off patent, and the largest seller, Lipitor scheduled to go off patent next year, researchers did leave open the possibility that industry leaders may seek a new indication for these blockbuster drugs.
"Until there is evidence from randomized trials, men should not take statins in order to prevent high-grade prostate cancer," said Eric Jacobs, Ph.D., strategic director of pharmacoepidemiology at the American Cancer Society. Jacobs, who wrote an accompanying editorial in the Cancer Epidemiology, Biomarkers & Prevention issue. He said a randomized trial among men without prostate cancer would need to be very large and might not be feasible.
"One possibility, however, would be a randomized trial among early stage prostate cancer patients opting for surveillance rather than immediate treatment, to see if statins could lower risk of prostate cancer progression," Jacobs said.
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