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microsatellite stable
A tumor classification indicating intact mismatch repair function, typically associated with lower immunotherapy response rates.
Full Definition
Microsatellite stable (MSS) tumors maintain functional DNA mismatch repair mechanisms, resulting in low mutation burden and minimal microsatellite length variations. Unlike microsatellite instability-high (MSI-H) tumors, MSS tumors generally have fewer neoantigens and are less responsive to immune checkpoint inhibitors. This classification is crucial for treatment selection, particularly in colorectal cancer where MSS status may indicate the need for combination chemotherapy rather than immunotherapy monotherapy.
Usage
Usage note: Often abbreviated as MSS in clinical reports. Contrasts with MSI-H tumors.
In Context
- "The microsatellite stable status suggested limited benefit from pembrolizumab monotherapy." — Molecular pathology report
- "Most colorectal cancers are microsatellite stable and require cytotoxic chemotherapy." — Treatment protocol
Also known as
MSS
mismatch repair proficient
Contrasted with
microsatellite instability-high
MSI-H
Don't confuse with
microsatellite instability
mismatch repair deficient