tumor mutation burden
The total number of somatic mutations per megabase of DNA in a tumor, used as a biomarker for immunotherapy response.
Full Definition
Tumor mutation burden (TMB) quantifies the number of somatic mutations present in a tumor's coding regions, typically expressed as mutations per megabase (mut/Mb). High TMB tumors are thought to produce more neoantigens that can be recognized by the immune system, potentially making them more responsive to immune checkpoint inhibitors. TMB can be assessed through whole exome sequencing or targeted gene panels. While TMB has shown promise as a biomarker across multiple tumor types, its clinical utility varies by cancer type and the specific assay used for measurement.
Usage
Usage note: Always include units (mut/Mb) when reporting numerical TMB values.
In Context
- "The tumor demonstrated high TMB at 15.2 mutations per megabase." — Genomic testing report
- "Tumor mutation burden analysis was performed using a 324-gene panel." — Laboratory methodology