UICC World Cancer Congress 2006

Despite years of research and hundreds of reports on prognostic markers in oncology, the number of tumor prognostic markers that have emerged as clinically useful is pitifully small. Some of the major problems and challenges faced in conducting prognostic factor research will be identified and discussed. For many markers, there is a perfusion of small studies with often conflicting or uninterpretable results. A variety of contributing factors have been cited, including general methodologic differences between studies, differing patient populations, poor study design, assays that are not standardized or lack reproducibility, and inappropriate or misleading statistical analyses. Common statistical problems include underpowered studies or overly optimistic reporting of effect sizes and significance levels due to multiple testing, subset analyses, and cutpoint optimization. Compounding the problem is the fact that many tumor marker studies have not been reported in a rigorous fashion, and published articles often lack sufficient information to allow adequate assessment of the quality of the study or the generalizability of study results. Suggestions are made for how to avoid some of the common pitfalls, how to identify problematic studies, and how to report tumor marker study results to maximize the interpretability and usefulness of the results.