(HealthDay News) – RECIST categories used to quantify tumor changes during exposure to anticancer therapies correlate well with overall survival (OS) but reflect a more linear continuum without clear inflection points, according to a study published online June 11 in the Journal of Clinical Oncology.

Rajul K. Jain, MD, of the University of Texas MD Anderson Cancer Center in Houston, and colleagues studied the correlation between OS and response, as quantified by RECIST, in 570 participants of 24 Phase I oncology trials conducted between October 2004 and May 2009.

The researchers found that 468 of the participants had quantifiable changes in tumor size. Change in tumor size during exposure to anticancer agents, as quantified by RECIST, correlated well with OS in a near-linear fashion without clear inflection points. Residual analyses were used to confirm the association.

“RECIST quantification of response correlates with survival, validating RECIST’s use in Phase I trials. However, the lack of apparent boundary values in the relationship between change in tumor size and OS demonstrates the arbitrary nature of the complete response/partial response/stable disease/progressive disease categories and questions emphasis placed on this categorization scheme,” the authors write. “Describing tumor responses as a continuous variable may be more informative than reporting categoric responses when evaluating novel anticancer therapies.”

One author disclosed a financial tie to Amgen.

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