There was a very interesting article published in the November 8, 2012 issue of the New England Journal of Medicine (vol. 367, pp 1792-1802) as well as an excellent analysis of the study published as an editorial comment in the same volume (pp 1848-1850). One theory about cancer growth is that those cells need cholesterol for cellular reproduction, so that any drug that lowers cholesterol should provide a benefit. The study was done in Denmark, which has a remarkably homogeneous population and moreover, because of national health care, has excellent registries of cancer diagnosis and incidence, as well as deaths from cancer, all cause mortality, and the prescribing of drugs. (The availability of such statistical data is one side benefit of national health care if the computer programs are written properly.)
The retrospective study reviewed data relating to medical care from 1995 to 2009, and encompassed almost 300,000 subjects. The hypothesis tested was that patients who were taking statins BEFORE the diagnosis of cancer would have a reduced cancer mortality. It was found that patients who were taking statins before the diagnosis of cancer had a reduction in their probability of dying from cancer from 100% to 85 % and the same reduction was found in mortality from any cause after the diagnosis of cancer. (The actual number of 85% +/- 2% is the hazard ratio, which is a statistical concept.) One remarkable fact was that the 15% reduction in mortality risk was independent of the dose of the statin(!).
Several clinical events and facts were not controlled for. No mention is made of cigarette smoking in the two groups, or if they had had cancer surgery. Also, no mention was made of OTC aspirin or NSAID use, and we know of several studies linking such use to a reduced incidence of colon cancer.
It is naturally suggested that a clinical study be made to test the hypothesis that was generated by this retrospective study, i.e. the hypothesis that statin use has a positive effect on cancer mortality as well as on all-cause mortality. I want to re-emphasize that this was a statistical analysis, and not a forward double-blind study so it would be tempting but scientifically incorrect to draw a clinical conclusion from the results. The problem I foresee is that no one will want to be in the placebo arm of the study, and risk not lowering his/her chance of dying. (This is in fact what happened when St. Vincent's Hospital in NYC tried to test drugs for AIDS with a placebo arm in the study. The political pressure was so great that the FDA granted the researchers permission to omit the placebo arm.) I predict that once the news of this study gets out to the general public, then millions of people will start taking statins of their own accord (probably from Mexico since almost every drug that is a prescription-only drug in the U.S. is sold OTC in Mexico).
Isn't the motto of Dupont, the giant chemical company, "Better living through chemistry"?