At present, it is very difficult, if not impossible, to draw reliable conclusions about the long-term risks of
lipid lowering
therapy. Many so-called "long-term" trials only cover a few years of treatment, comparative studies versus placebo are very rare and the notification of acute events in the context of pharmacovigilance does not provide information about the long-term risk. However, analysis of large scale primary or
secondary prevention trials, the
Lipid Research Clinics study with
cholestyramine, the Helsinki cardiological study with
gemfibrozil, the Coronary
Drug Project with
clofibrate and
nicotinic acid, has not shown any significant differences between the treatment and control groups, in particular with regards to the prevalence of malignant disease. These reassuring observations contradict those of the WHO study with
clofibrate: a significant increase in the incidence of
cancer, especially gastrointestinal, is observed in the treatment group. Therefore, despite the absence of confirmed long-term clinical or
biological adverse effects of
lipid lowering drugs (apart from the WHO
clofibrate study), the physician must remain vigilant, especially as the long-term risks are difficult to assess.