Chemoprevention of cancer: a controversial and instructive story

Increased intake of fruits and vegetables seems to be one of the simplest means of decreasing the risk for cancer. Cancer-preventive effects of fruits and vegetables have been observed in epidemiological studies, which could not, however, distinguish the effects of the various ingredients. Antioxidant defence has been proposed as a mechanism of chemoprevention, although inconclusive results have been obtained. The results of randomized intervention trials have shown that beta-carotene supplements are of limited value and may even be deleterious. Vitamins are a good marker of the ingestion of fruits and vegetables, and vitamin E (alpha-tocopherol) is a lipid-soluble antioxidant which can scavenge free radicals. It has no significant effect on the risk for lung cancer of long-term smokers in an intervention trial, but it decreased both the incidence of and mortality from prostate cancer; however, there was a 50% increase in the occurrence of cerebral haemorrhage among the men given vitamin E. Aspirin and aspirin-like drugs appear to decrease the risk for intestinal tumours; the mechanism of action appears to involve diminishing prostaglandin production due to inhibition of cyclooxygenases. Dietary fibre has been linked to a reduced risk for colorectal cancer in many observational studies, but opposite findings were reported recently. In order to resolve these paradoxes, we need to understand better the underlying biology, develop mechanistic hypotheses and test them in clinical trials in humans. Until that time, we should confine any premature enthusiasm for chemopreventive micronutrient supplementation.     

Recombinant human follicle-stimulating hormone: a controversial issue--without controversy

Recent developments in recombinant DNA technology have resulted in a rapidly expanding range of new diagnostic and therapeutic opportunities. This technology paved the way for identification, isolation, cloning and production of specific proteins. Recently, recombinant human gonadotropins became available for clinical use. Pharmacokinetics, receptor availability, pharmacodynamics and safety were extensively studied and the drugs were found to be identical, if not superior, to urinary gonadotropins that have been used in reproductive medicine for the last 40 years. It is currently apparent that the use of recombinant human gonadotropins is expected to provide improved batch-to-batch consistency, steady supply and most importantly, a purified compound with highly specific activity, which accounts for > 99% of the protein content of the preparation, making it possible to administer subcutaneously. The purpose of this report is to describe and evaluate recent developments in the use of recombinant human follicle-stimulating hormone.