[Surrogate and true endpoints in cancer clinical trials]

To facilitate the proper and quick evaluation of cancer chemotherapy, the issues of surrogate and true endpoints in clinical trials were reviewed. Surrogate endpoints are defined as response variables that can substitute for a true endpoint due to their close correlation with the true endpoint, and their occurrence earlier than true endpoint. The response rate in cancer chemotherapy has been used as a surrogate or true endpoint for the evaluation of treatments. However, recent studies revealed that response rates do not always correlate with survival time (time to failure), and better surrogate endpoints such as time to progression, median survival time, or various surrogate biomarkers are now under investigation.