Comparison of local versus central tumor measurements in a multicenter cancer trial

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Abstract
A total of 419 solid tumors from 92 patients were measured by a local team consisting of physician and nurse oncologist or physician''s assistant, and centrally by 1 radiologist. The central radiologist alo remeasured 137 tumors on 30 patients to assess intraexaminer agreement. Tumor measurements at specific points in time, as well as changes in tumor mesurements over time, were evaluated. When signed differences were calculated, there was little overall difference betwen local and central examiners, although 3 of the 8 centers did show a significant difference. When absolute differences were calculated, the relative errors of the width times length products ranged from 35-55%. Although local and central examiners agreed 75% of the time on change in disease, there was only 42% agreement on the subset of patients who had a remission. In general, the intraexaminer agreement was slightly better than the interexaminer agreement. Apparently, solid tumor measurements are not particularly reliable, and survival time remains the most satisfadctory endpoint in a cancer clinical trial.