ABSTRACT
The most popular primary endpoint in phase II cancer clinical trials is tumor response, resulting in a binary variable. Often, however, a time-to-event endpoint, such as time-to-disease progression or overall survival (meaning time to death by any cause) starting from registration, may be chosen as the primary endpoint of a phase II trial when a typical tumor response endpoint is not applicable or is not clinically relevant. For example, in studies involving blood cancers or in the case of surgical studies with adjuvant chemotherapies, where the tumor is completely resected, so that tumor response is not a meaningful endpoint. Also, cytostatic therapies are to prevent the growth of tumor rather than to shrink it, so that tumor response cannot be a good endpoint for phase II trials on experimental cytotoxic therapies. In these cases, a popular clinical outcome of interest may be the time to a specific event, such as disease progression or death. Because of loss to follow-up or termination of study, event times are subject to right censoring. Based on the standard terminology, we use time-to-event and survival time together regardless of the type of event, in this book.
