NAACCR Item #3890: Microsatellite Instability (MSI)
| Item # | Length | Source of Standard | Section Name | Year Implemented | Version Implemented | XML NAACCR ID | Parent XML Element |
|---|---|---|---|---|---|---|---|
| 3890 | 1 | NAACCR | Stage/Prognostic Factors | 2018 | 18 | microsatelliteInstability | Tumor |
Required Status:
NPCR Collect: Required, site specific; when available
CoC Collect: Required, site specific
SEER Collect: Required, site specific
CCCR Collect: Required, site specific; when available
Description
The microsatellite instability (MSI) test is a genetic test performed on tumor tissue to look for differences in length of certain non-functioning sections of DNA. The differences are caused by problems with the genes that encode proteins that normally repair certain types of DNA damage. Knowing whether cancer is microsatellite instability high may help plan the best treatment.
Microsatellites are short, repeated, sequences of DNA. Cancer cells that have large numbers of microsatellites that may have defects in the ability to correct mistakes that occur when DNA is copied in the cell. Microsatellite instability is found most often in colorectal cancer, other types of gastrointestinal cancer, and endometrial cancer. It may also be found in cancers of the breast, prostate, bladder, and thyroid.
Rationale
Microsatellite Instability (MSI) is a Registry Data Collection Variable in AJCC. It was previously collected as Colon and Rectum, CS SSF# 7.
Allowable Values
0-2, 8, 9
Codes
| Code | Description |
|---|---|
| 0 | Microsatellite instability (MSI) stable; microsatellite stable (MSS); negative, NOS AND/OR Mismatch repair (MMR) intact, no loss of nuclear expression of MMR proteins MMR proficient (pMMR or MMR-P) |
| 1 | MSI unstable low (MSI-L) |
| 2 | MSI unstable high (MSI-H) AND/OR MMR-D (dMMR or MMR-D), loss of nuclear expression of one or more MMR proteins, MMR protein deficient) |
| 8 | Not applicable: Information not collected for this case (If this information is required by your standard setter, use of code 8 may result in an edit error.) |
| 9 | Not documented in medical record MSI-indeterminate MSI-equivocal Microsatellite instability not assessed or unknown if assessed |
Code Notes
Each Site-Specific Data Item (SSDI) applies only to selected primary sites, histologies, and years of diagnosis. Depending on applicability and standard-setter requirements, SSDIs may be left blank.