microsatellite stable
Also written as: MSS — Microsatellite Stable
A tumor classification indicating normal DNA mismatch repair function and low immunotherapy responsiveness.
Full Definition
Microsatellite stable (MSS) describes tumors with intact DNA mismatch repair machinery, resulting in stable microsatellite sequences and typically lower mutation rates. MSS tumors generally have fewer neoantigens and respond poorly to immune checkpoint inhibitors compared to microsatellite instability-high tumors. This classification is crucial for treatment selection, particularly in colorectal cancer where MSS status often indicates need for conventional chemotherapy rather than immunotherapy.
Usage
Usage note: Often contrasted with MSI-H; ensure clear distinction in clinical documentation.
In Context
- "The colorectal adenocarcinoma was classified as microsatellite stable, indicating poor response to immunotherapy." — Pathology report
- "MSS tumors require alternative therapeutic approaches beyond checkpoint inhibition." — Treatment planning document