Ethics and designs: laetrile trials as an example.

The National Cancer Institute instituted a search for cancer patients who have had objective benefit from Laetrile therapy. Cases have been solicited through a nationwide mailing to > 450,000 physicians and other health professionals, through publicity in the medical and lay press, and by contact with the pro-Laetrile groups. As a result, a retrospective analysis of the medical records of patients who volunteered their cases and who believed they had objective antitumor benefit from Laetrile therapy has been carried out. Similar criteria for response that are used for any National Cancer Institute-sponsored investigational agent were used to evaluate possible Laetrile antitumor activity. This analysis was not designed to determine a response rate to Laetrile. It is uncontrolled, only positive responders were solicited, and the total number of cases treated with Laetrile was not available. It is believed that if any objective benefit for Laetrila therapy exists, then at least hints of this should be made evident by this retrospective evaluation. Data collected were used to assist in deciding if clinical trials of Laetrile are warranted.