Comparison of young clinical investigators' accuracy and reproducibility when measuring pulmonary and skin surface nodules using a circumferential measurement versus a standard caliper measurement: American Association for Cancer Research/American Society of Clinical Oncology Clinical Trials Workshop

Purpose: The clinical investigator must understand that errors in measuring tumors can greatly affect such clinical-trial end points as tumor response . We performed a prospective, controlled study of tumor measurements that c ompared circumferential measurements made with a loop planimeter with linea r measurements made with a standard caliper. Methods: Using a cross-over design, 76 clinical oncology fellows/junior onc ology faculty members attending a Methods in Clinical Cancer Research Works hop sponsored by the American Association for Cancer Research and the Ameri can Society of Clinical Oncology measured five pulmonary nodule phantoms th at ranged in size from 1.76 to 13.21 cm(2) and five surface nodule phantoms with sizes ranging from 2.3 to 12.9 cm(2). To perform these measurements, they used both a loop planimeter and a caliper. Forty-two and 40 participan ts repeated measurements 3 days later on pulmonary and surface nodules. Acc uracy, reproducibility, and time efficiency were evaluated. Results: The linear caliper measurements overestimated pulmonary nodule and surface nodule size by a median of 37% and 23%, respectively. Circumferent ial loop planimeter measurements overestimated pulmonary nodule size and su rface nodule size by a median of 8% and 17%, respectively. Interobserver re producibility for the planimeter was greater than that for the caliper, as evidenced by thinner measurement interquartile ranges. Furthermore, intraob server reproducibility was higher for the planimeter, with its variability being only 31.4% and 25.5% as large as that of the caliper when measuring t he pulmonary and surface nodules, respectively. Conclusion: Circumferential measurements provide better accuracy, reproduci bility, and speed in measuring both pulmonary and surface nodules than do p erpendicular diameters, (C) 2000 by American Society of Clinical Oncology.