Detecting a Survival Benefit to Dose Escalation

To the Editor We commend Michalski et al for reporting the anticipated results of RTOG 0126, and in particular, for reporting the incidences of both all-cause and cause-specific mortality. Surprisingly, many trials do not report this vital information. The incidence of prostate cancer mortality was unexpectedly low in their trial, possibly owing to improvement in salvage therapies and changes in the patient population. We are concerned that the proposed effect size (hazard ratio, 0.77) on overall survival (OS) was, in retrospect, mathematically infeasible, and therefore the true power of this study to detect an OS benefit with dose escalation is much lower than 90%.

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