The role of meta-analyses in assessing cancer treatments

The results of individual phase III cancer clinical trials are often inconclusive due to the overly optimistic size of treatment differences that are sought. Increased power and precision can generally be obtained if the data from several different trials studying the same or similar questions are analysed together. Individual patient data meta-analyses, which combine together the quantitative results from all properly randomised studies, provide an overall estimate of the size of treatment differences. Individual patient data meta-analyses have played an especially important role in breast and gastrointestinal tract cancers where many important questions have been addressed. Although meta-analyses have been subject to considerable criticism, individual patient data meta-analyses provide the best overall evidence of treatment effect in the absence of large-scale trials and have been instrumental in providing objective data that can be used in the design of new studies.