====== Objective response rate ======

When used as a clinical endpoint for clinical trials of cancer treatments, this often called the objective [[response rate]] (ORR). The FDA definition of ORR is "the proportion of patients with tumor size reduction of a predefined amount and for a minimum time period."

However, [[PFS]] and ORR also have challenges, as determination of response and [[progression]] using anatomic imaging techniques may suffer from issues associated with measurement variability and discordance in interpretation between radiologists
((Provenzale JM, Ison C, Delong D. Bidimensional measurements in brain tumors:
assessment of interobserver variability. AJR Am J Roentgenol. 2009
Dec;193(6):W515-22. doi: 10.2214/AJR.09.2615. PubMed PMID: 19933626.
))