partial response
Tumor response category indicating significant reduction in tumor burden but not complete disappearance.
Full Definition
Partial response (PR) is a standardized oncological endpoint defined as a decrease of at least 30% in the sum of longest diameters of target lesions, taking as reference the baseline sum longest diameters. This measurement must be confirmed by repeat assessments at least four weeks apart. Partial response represents meaningful clinical benefit and is often considered a successful treatment outcome in oncology trials. The designation requires that no new lesions appear and that existing non-target lesions do not progress unequivocally.
Usage
Usage note: Always specify measurement criteria used when reporting partial response in clinical documentation.
In Context
- "The patient achieved a partial response after three cycles of immunotherapy." — Treatment response assessment
- "Partial response rates were significantly higher in the experimental arm (42% vs 18%)." — Clinical trial results