pseudoprogression
Pronunciation: soo-doh-pruh-GRESH-un
Apparent tumor growth on imaging that represents treatment-related changes rather than true disease progression.
Full Definition
Pseudoprogression is a phenomenon where imaging studies show apparent tumor enlargement or new enhancement that mimics disease progression but actually represents treatment-related inflammation, necrosis, or immune response. This occurs most commonly following radiation therapy, immunotherapy, or certain targeted treatments. In oncologic radiology, distinguishing pseudoprogression from true progression is challenging but critical for treatment decisions. Advanced imaging techniques such as perfusion MRI, PET metabolism studies, and diffusion-weighted imaging may help differentiate these entities. The RANO (Response Assessment in Neuro-Oncology) criteria specifically address pseudoprogression in brain tumor evaluation.
Usage
Usage note: Single word without hyphen; distinguish clearly from true progression in reports.
In Context
- "The apparent tumor enlargement was determined to be pseudoprogression rather than treatment failure." — Brain tumor follow-up report
- "Given the recent immunotherapy initiation, pseudoprogression should be considered before changing treatment." — Oncology consultation note