Tumor mutation burden [Interpretation]

TMB Tumor-Imp

Definition

Tumor mutational burden (TMB), also known as mutation load, is a biomarker for various cancer types to identify patients who will benefit from immunotherapy, such as immune checkpoint blockade (ICB) therapy. Testing can be performed by whole exome sequencing (WES) or next-generation sequencing (NGS). Various quantitative and ordinal results may be reported, so it is important to distinguish the type of results when mapping to LOINC. Quantitative results typically include the number of mutations detected per megabase (mut/Mb), often by NGS, in a tumor specimen [LOINC: 94076-7]. The mutations targeted may include non-synonymous or both synonymous and non-synonymous mutations. Quantitative TMB results have also been reported as the total number of mutations detected by whole exome sequencing (WES). We encourage labs to report how results are determined or calculated in either the structured message format or using another LOINC. An ordinal TMB result (this term) of high, low, etc., may also be reported to provide an overall interpretation for the quantitative value (muts/Mb). Cut-offs vary across assays and for each tumor type, so it is important to know which assay was used to determine the overall ordinal TMB result.

Cancer; Impression; Impression/interpretation of study; Impressions; Interp; Interpretation; Molecular pathology; MOLPATH; MOLPATH.MUTATIONS; Mut; Mutations; Ordinal; Point in time; QL; Qual; Qualitative; Random; Screen; TMB; Tumor mutational load; tumors; tumour; tumours