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HelpTest Code TMSI Microsatellite Instability, Tumor
Necessary Information
1. A pathology report (final or preliminary) is required and must accompany specimen for testing to be performed.
2. The following information must be included in the report provided.
-Patient name
-Block number-must be on all blocks, slides and paperwork (can be handwritten on the paperwork)
-Date of tissue collection
-Source of the tissue
Specimen Required
This assay requires at least 40% tumor nuclei for endometrial specimens and at least 20% tumor nuclei for colorectal specimens.
-Preferred amount of tumor area with sufficient percent tumor nuclei: tissue 72 mm(2)
-Minimum amount of tumor area: 18 mm(2)
-These amounts are cumulative over up to 10 unstained slides and must have adequate percent tumor nuclei.
-Tissue fixation: formalin-fixed paraffin-embedded, non-decalcified
Preferred:
Specimen Type: Tissue block
Collection Instructions: Submit a formalin-fixed, paraffin-embedded tissue block with acceptable amount of tumor tissue.
Acceptable:
Specimen Type: Tissue slide
Slides: 1 Hematoxylin and eosin stained and 5 unstained
Collection Instructions: Submit 1 slide stained with hematoxylin and eosin and 5 unstained, nonbaked slides with 5-micron thick sections of the tumor tissue.
Note: The total amount of required tumor nuclei can be obtained by scraping up to 5 slides from the same block.
Forms
1. Molecular Genetics: Inherited Cancer Syndromes Patient Information (T519)
2. If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-Gastroenterology and Hepatology Test Request (T728)
-Oncology Test Request (T729)
Useful For
Evaluation of tumor tissue to identify patients at high risk for having Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer
Evaluation of tumor tissue for clinical decision-making purposes given the prognostic and therapeutic implications associated with microsatellite instability phenotypes
Testing Algorithm
When this test is ordered, slide review will always be performed at an additional charge.
For more information see Lynch Syndrome Testing Algorithm
Special Instructions
Method Name
Polymerase Chain Reaction (PCR)
Reporting Name
Tumor, Microsatellite InstabilitySpecimen Type
VariesSpecimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | ||
| Frozen | |||
| Refrigerated | |||
Reference Values
An interpretive report will be provided.
Interpretation
The report will include specimen information, assay information, and interpretation of test results.
Microsatellite stable (MSS) is reported as MSS (0 or 1 of 7 markers demonstrating instability) or microsatellite instability-high (MSI-H) (2 or more of 7 markers demonstrating instability).
Clinical Reference
1. Baudhuin LM, Burgart LJ, Leontovich O, Thibodeau SN. Use of microsatellite instability and immunohistochemistry testing for the identification of individuals at risk for Lynch syndrome. Fam Cancer. 2005;4(3):255-265
2. Terdiman JP, Gum JR Jr, Conrad PG, et al. Efficient detection of hereditary nonpolyposis colorectal cancer gene carriers by screening for tumor microsatellite instability before germline genetic testing. Gastroenterology. 2001;120(1):21-30
3. Popat S, Hubner R, Houlston RS. Systematic review of microsatellite instability and colorectal cancer prognosis. J Clin Oncol. 2005;23(3):609-618
4. Ribic CM, Sargent DJ, Moore MJ, et al. Tumor microsatellite-instability status as a predictor of benefit from fluorouracil-based adjuvant chemotherapy for colon cancer. N Engl J Med. 2003;349(3):247-257
5. Idos G, Valle L. Lynch syndrome. In: Adam MP, Mirzaa GM, Pagon RA, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 2004. Updated February 4, 2021. Accessed July 30, 2024. Available at www.ncbi.nlm.nih.gov/books/NBK1211/
6. Kawakami H, Zaanan A, Sinicrope FA. Microsatellite instability testing and its role in the management of colorectal cancer. Curr Treat Options Oncol. 2015;16(7):30
7. Sargent DJ, Marsoni S, Monges G, et al. Defective mismatch repair as a predictive marker for lack of efficacy of fluorouracil-based adjuvant therapy in colon cancer. J Clin Oncol. 2010;28(20):3219-3226
8. Le DT, Durham JN, Smith KN, et al. Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade. Science. 2017;357(6349):409-413
9. Overman MJ, Lonardi S, Wong KYM, et al. Durable clinical benefit with nivolumab plus ipilimumab in DNA mismatch repair-deficient/microsatellite instability-high metastatic colorectal cancer. J Clin Oncol. 2018;36(8):773-779
Day(s) Performed
Varies
Report Available
4 to 7 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
81301
88381-Microdissection, manual
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| TMSI | Tumor, Microsatellite Instability | 81711-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 609365 | Result Summary | 50397-9 |
| 609366 | Result | 43368-0 |
| 609367 | Interpretation | 69047-9 |
| 609368 | Specimen | 31208-2 |
| 609369 | Source | 31208-2 |
| 609370 | Tissue ID | 80398-1 |
| 609371 | Released By | 18771-6 |
Additional Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| SLIRV | Slide Review in MG | No, (Bill only) | Yes |
Specimen Minimum Volume
See Specimen Required