pseudoprogression
Pronunciation: SOO-doe-pro-GRESH-un
Apparent tumor growth on imaging that represents immune infiltration rather than true disease progression.
Full Definition
Pseudoprogression describes the radiological appearance of tumor growth that actually represents immune cell infiltration and inflammation rather than cancer progression. This phenomenon occurs primarily with immunotherapy treatments where activated immune cells infiltrate the tumor, causing temporary enlargement on imaging studies. Distinguishing pseudoprogression from true progression is crucial for treatment decisions, often requiring delayed imaging assessment or tissue confirmation to avoid premature treatment discontinuation in patients who may be responding to therapy.
Usage
Usage note: Write as one word; distinguish clearly from true progression in clinical documentation.
In Context
- "The apparent 25% increase in tumor size was ultimately determined to be pseudoprogression rather than treatment failure." — Radiology consultation report
- "Pseudoprogression rates with anti-PD-1 therapy range from 5-15% across different tumor types." — Medical literature review