Methodologic considerations for trials of lung cancer prophylaxis.

Prophylaxis is likely to be of increasing importance in the control of lung cancer. Areas already suggested as potential fields of investigation include the use of specific immunoprophylaxis or synthetic retinoids. Thorough evaluation of the effects and hazards of such prophylaxis will be required, and the most satisfactory approach is to conduct controlled prophylactic trials. Such trials must rest on the same basic principles as those established for therapeutic trials. However, new problems bearing on ethical requirements, the sampling procedure, and the practical conduct of the trials will arise. Compliance, adverse effects, end points for analysis of the prophylactic effects, and rules for when to stop a trial are discussed.