BOSTON — Among men with prostate cancer, those with low plasma cholesterol are significantly less likely to develop more aggressive forms of the disease, compared with those who have higher cholesterol levels, Elizabeth A. Platz, Sc.D., reported at the annual international conference of the American Association for Cancer Research.
In a previous study, Dr. Platz of Johns Hopkins University in Baltimore and her colleagues showed that men who use statin drugs have a significantly reduced risk of developing advanced prostate cancer, suggesting a possible link between cholesterol status and disease progress. Because prostate cancer cells exhibit cholesterol dysregulation and because cholesterol affects multiple factors that could influence carcinogenesis, including sex steroid hormone production and cell-signaling pathways, the investigators narrowed their focus to cholesterol levels specifically for the current investigation, according to Dr. Platz.
To determine whether lower plasma cholesterol is associated with a lower risk of prostate cancer overall, as well as by stage and grade, the investigators compared blood cholesterol levels from nearly 1,400 men enrolled in Harvard University's Health Professionals Follow-up Study who provided a blood sample between 1993 and 1995. The study population included 698 men with incident prostate cancer diagnosed after the blood draw through January 2000, and 698 prostate cancer-free men who were individually matched based on age and other factors.
The mean plasma cholesterol levels were similar in the prostate cancer patients and the controls, “suggesting that cholesterol was not involved in the initial development of prostate cancer,” Dr. Platz said.
But logistic regression analysis showed that prostate cancer patients with cholesterol levels in the lowest quartile, compared with those in the highest quartile, had a significantly reduced risk of developing more advanced disease. “The risk of having high-grade disease [Gleason score of 7 or higher] was reduced by nearly 40% among men in the lowest cholesterol quartile, and the risk of having advanced disease [tumor stage IIIB or worse] was reduced by 50%,” Dr. Platz reported.
After excluding men who had ever used cholesterol-lowering drugs, the risk of developing high-grade or advanced disease among prostate cancer patients in the lowest cholesterol quartile was reduced by 33% and 27%, respectively, compared with the highest quartile, she said.
Although the study is limited by its observational design, when considered in conjunction with the earlier statin findings, “the results suggest that we may be able to prevent dangerous prostate cancers by tampering with cholesterol metabolism,” Dr. Platz noted.