Aromatase inhibitors: current status.

To review the aromatase inhibitors with emphasis on the newer agents that are being developed for the treatment of metastatic breast cancer. Review of English literature over the past 5 years using Med-Line and Cancer-Line computer search. All pertinent articles were included for this review. Source of estrogen in the human body and means of its ablation are discussed with emphasis on aromatase inhibition. Aminoglutethimide was highlighted as the prototype for inhibition of aromatase. All other agents that have aromatase inhibitory effect, as well as, antitumor effect were discussed in reference to their structure, chemistry, pharmacology, and pharmacokinetics in animals and humans. Their respective antitumor effect in experimental studies and humans, including dose-schedules responses and side effects, are also reviewed. New aromatase inhibitors have significant antitumor activity in breast cancer and may have better therapeutic index than currently available drugs.