The analysis of case-control studies of the efficacy of screening for recurrence of cancer.

Occasionally, the efficacy of screening for cancer recurrence has been evaluated by means of case-control studies. However, these studies generally have not been designed and analyzed in a manner that will yield an unbiased result. The commentary shows that by adhering to the principles developed for the analysis of studies of the efficacy of screening for the presence of a given cancer in persons with no history of this disease, a case-control study of screening for recurrence will improve its chances of obtaining valid findings.