Interpreting Measures of Treatment Effect in Cancer Clinical Trials

The efficacy of a new cancer regimen is usually assessed by analyzing outcomes such as tumor response and overall survival. Many publications summarizing results of cancer clinical trials report measures such as odds ratios and hazard ratios, as these are the estimators of treatment effect obtained from regression models used to analyze the data. However, these measures are sometimes misinterpreted, as they are not necessarily familiar to many readers. The most common mistake is to interpret both measures as relative risks, an interpretation that can lead to an incorrect impression of the impact of the treatment on response and survival.