Cholesterol-lowering drugs may cause cancer, a possibility that doctors and regulators would have been aware of had they read the research properly.

Scientists from the University of California have reanalyzed the data published in the American drug reference bible, Physicians' Desk Reference, to discover a definite link between most of the popular cholesterol-lowering drugs and cancer. Tests carried out on rodents show the carcinogenic effects of the drugs, especially if taken longer-term.

Their findings cast a shadow over the millions of users of the drugs around the world. They are some of the most popularly prescribed drugs; their usage has increased 10-fold in the past decade and, in 1992 in the US alone, 26 million prescriptions for the drugs were written out.

The Californian researchers, Thomas Newman and Stephen Hulley, fear that modern medicine may be preparing a massive cancer time bomb, its effects not fully realized for another 30 years.

Despite this, the benefits of the drugs outweigh the risks among those with high blood cholesterol, especially men - and provided they have taken the drug for under five years. Those not at high risk from raised cholesterol levels should avoid the treatment, the researchers advise, particularly if they have a life expectancy greater than 20 years.

But if all these risks were already in the data submitted to the Food and Drug Administration, the US drug regulator, how did the drugs get approved in the first place?

The Californian researchers note that the drugs were approved on the basis of less than 10 years' clinical trials, yet the full effects of the drugs may not become clear for 30 years.
The carcinogenic effects of two of the drugs, lovastatin and gemfibrozil, were discussed in a drugs advisory committee meeting by a drug manufacturer representative who 'downplayed the importance of the studies', the researchers say. The data were also prepared in milligrams per kilogram of body weight, which may have misled the committee.

Despite this, the committee still recommended that gemfibrozil should be used as a last resort drug, after exercise, diet and weight loss had failed to bring down cholesterol levels. The popularity of the drug since then suggests it has been far more widely used than the committee wanted (JAMA, January 3, 1996).

* Is it the drugs that cause the cancer, or the lower levels of cholesterol that bring on the condition? The Californian researchers concluded that it was the drugs themselves, a view shared by Jonathan Tobert, a researcher at Merck Laboratories. Writing in The Lancet, he said that other research shows there are risks with some drugs, but that 'cholesterol lowering is not hazardous per se' (The Lancet, January 13, 1996).