Correlation of patient survival with clinical tumor measurements in malignant pleural mesothelioma.

ABSTRACT

OBJECTIVES: To evaluate differences in the tumor response classifications that result from clinical measurements and to compare these response classifications with overall survival for patients with malignant pleural mesothelioma (MPM). METHODS: One hundred thirty-one computed tomography (CT) scans were collected from 41 MPM patients enrolled in a clinical trial. Primary measurements had been acquired by clinical radiologists at a single center during routine clinical workflow, and the variability of these measurements was investigated. Retrospective measurements were acquired by a single radiologist in compliance with the study protocol based on the modified response evaluation criteria in solid tumors (RECIST). Differences in response classification categories by the two measurement approaches were evaluated and compared with patient survival. RESULTS: Eleven (27%) of the 41 MPM patients had primary measurements at baseline or at follow-up that deviated from the guidelines of the clinical trial protocol. Among the 41 baseline scans, no statistical difference was observed in summed tumor measurements between primary and retrospective measurements. Response classification based on primary and retrospective measurements was different in 23 (26%) of the 90 follow-up scans, and best response was the different in seven (17%) of the 41 patients. Using Harrell's C statistic as a measure of correlation, response based on retrospective measurements correlated better with survival (C = 0.62) than did response based on primary measurements (C = 0.57). CONCLUSIONS: Strict compliance with the measurement protocol yields tumor response classifications that may differ from those obtained in clinical practice. Response based on retrospective measurements correlated better with survival than did response based on primary measurements. KEY POINTS • Response classifications could be different between clinical primary and retrospective measurements for malignant pleural mesothelioma. • Response classifications obtained by strict compliance with the trial-specific protocol correlated better with survival than the classifications based on primary measurements. • Quality assurance and radiologist training measures should be used to ensure the integrity of image-based tumor measurements in mesothelioma clinical trials.