RECIST vs. WHO: prospective comparison of response criteria in an EORTC phase II clinical trial investigating ET-743 in advanced soft tissue sarcoma.

The present study was set up just after the publication of the response evaluation criteria in solid tumors (RECIST) as a prospective validation exercise in soft tissue sarcoma. Forty-nine patients were entered into a phase II clinical trial aiming at determining the activity and safety of ET-743 (Ecteinascidin) in second line advanced soft tissue sarcoma. Response to treatment and progression were monitored following the WHO criteria and RECIST. Discordances between WHO and RECIST criteria for the best response were reported for two cases: one no-change (WHO) reported as partial response (RECIST) and one progression (WHO) reported as no-change (RECIST). In terms of date of progression, 3 patients progressed on WHO criteria while they were still stable with RECIST. Overall the results of the study would not have changed if RECIST had been used instead of WHO criteria. In conclusion, response criteria as defined by RECIST are adequate to measure response and progression in non-GIST soft tissue sarcoma and can be used instead of the modified WHO criteria.