Progression-free survival and response rate appeared to be suitable surrogates for overall survival in advanced soft tissue sarcoma, according to a study published in the Journal of Clinical Oncology.1

It was also found that there was a poor correlation between 3- and 6-month progression-free survival and overall survival. Investigators cautioned against the use of these as primary endpoints in soft tissue sarcoma trials.

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The rationale for the study was that randomized controlled trials in soft tissue sarcoma have used varying endpoints and the surrogacy of the endpoints was unknown.

In this systematic review of systemic therapy of randomized controlled trials in soft tissue sarcoma, surrogacy between intermediate endpoints and overall survival was explored using weighted liner regression for the hazard ratio for overall survival with the hazard ratio for progression-free survival or the odds ratio for response rate, 3- and 6-month progression-free survival. Investigators also evaluated the quality of reporting for efficacy and toxicity.

A total of 53 randomized controlled trials published between 1974 and 2014 were analyzed. A total of 9762 patients were included.

Results showed that there were significant correlations between progression-free survival and overall survival (R = 0.61) and between response rate and overall survival (R = 0.51). Nonsignificant correlations were observed between overall survival and 3- or 6-month progression-free survival.

Researchers found that in 14% of trials, the primary endpoint was not met yet the study was reported as being positive.

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In regard to safety, toxicity was comprehensively reported in 47% of randomized controlled trials, and 14% inadequately reported toxicity.

The authors concluded that “the quality of toxicity reporting and interpretations of results is suboptimal.”


  1. Zer A, Prince RM, Amir, E, Razak AA. Evolution of randomized trials in advanced/metastatic soft tissue sarcoma: endpoint selection, surrogacy, and quality of reporting [published online ahead of print March 7, 2016].  J Clin Oncol. doi: 10.1200/JCO.2015.64.3437.