Discrepancy in the assessment of tumor response in patients with pancreatic cancer: WHO versus RECIST criteria.

Purpose: The Response Evaluation Criteria in Solid Tumors (RECIST) have largely replaced the World Health Organization (WHO) criteria as a preferred method for assessing tumor response in clinical trials. We hypothesized that due to frequent asymmetric growth pattern, as well as somewhat diffuse margins of pancreatic cancer, the use of WHO vs. RECIST criteria may result in significantly different tumor response assessments. The purpose of this retrospective study was to compare the WHO (bidimensional) to RECIST (unidimensional) in assessing treatment response in pancreatic cancer patients enrolled in clinical trials.

Materials And Methods: We have evaluated the contrast- enhanced computed tomography (CT) images from 12 pancreatic cancer patients with measurable disease enrolled in two phase I/II clinical trials at the Arizona Cancer Center, between July 2000 and July 2003. The tumor measurements were re-calculated by RECIST and WHO criteria and were compared.

Results: In 3 out of the 12 patients (25%) there was discordant response categorization when WHO criteria were used instead of RECIST. Clinical presentations in all 3 patients were more consistent with WHO categorization.

Conclusion: Our retrospective data analysis suggests that use of different tumor response criteria (RECIST vs. WHO) may result in different assessments of treatment efficacy in patients with pancreatic cancer on clinical trials. This finding warrants further confirmation in a larger prospectively designed trial.