Patient heterogeneity and allocation bias: how should they be reported in clinical trials of chemotherapy for advanced gastric cancer?

Excerpt

Successful phase III trials improve the standard of care for cancer patients by providing new treatment regimens that have superior survival rates, less toxicity, or both when compared with conventional regimens. However, the external validity or generalizability of trial results depends directly on the extent to which the results are applicable to the patient population of a specific practice. Selection bias can seriously influence the external validity of a clinical trial. Participants in clinical trials tend to have better survival outcomes than do nonparticipants. In addition, differences among the patient characteristics that are reported in trials complicate direct comparisons between reports. Therefore, the presentation of baseline patient characteristics is a critical component of any study report on treatment for cancer. Patient characteristics should be presented clearly, so that all readers—physicians, oncologists, and other healthcare decision-makers—can confirm, to the extent possible, whether the study population is representative of that seen in their clinical practice. …