Tumor, Microsatellite Instability
GTR Test Accession: Help GTR000597583.2
Last updated in GTR: 2024-03-25
Last annual review date for the lab: 2024-05-28 LinkOut
At a Glance
Prognostic; Screening; Therapeutic management
Colorectal cancer
Microsatellite Instability
Molecular Genetics - Microsatellite instability testing (MSI): RT-PCR
Evaluation of tumor tissue to identify patients at high risk …
Not provided
Guidance for management
Ordering Information
Offered by: Help
Test short name: Help
Specimen Source: Help
Who can order: Help
  • Genetic Counselor
  • Health Care Provider
  • Licensed Dentist
  • Licensed Physician
  • Nurse Practitioner
  • Physician Assistant
  • Public Health Mandate
  • Registered Nurse
Test Order Code: Help
CPT codes: Help
**AMA CPT codes notice
Lab contact: Help
Megan Hoenig, MS, MPH, Certified Genetic counselor, CGC, Genetic Counselor
Contact Policy: Help
Laboratory can only accept contact from health care providers. Patients/families are encouraged to discuss genetic testing options with their health care provider.
How to Order: Help
Order URL
Test development: Help
Test developed by laboratory (no manufacturer test name)
Informed consent required: Help
Based on applicable state law
Pre-test genetic counseling required: Help
Decline to answer
Post-test genetic counseling required: Help
Decline to answer
Recommended fields not provided:
Conditions Help
Total conditions: 1
Condition/Phenotype Identifier
Test Targets
Analytes Help
Total analytes: 1
Analyte Associated Condition
Total methods: 1
Method Category Help
Test method Help
Instrument *
Microsatellite instability testing (MSI)
* Instrument: Not provided
Clinical Information
Test purpose: Help
Prognostic; Screening; Therapeutic management
Clinical utility: Help
Guidance for management
View citations (1)
  • Use of microsatellite instability and immunohistochemistry testing for the identification of individuals at risk for Lynch syndrome. Baudhuin LM, et al. Fam Cancer. 2005;4(3):255-65. doi:10.1007/s10689-004-1447-6. PMID: 16136387.

Target population: Help
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.
View citations (9)
  • Efficient detection of hereditary nonpolyposis colorectal cancer gene carriers by screening for tumor microsatellite instability before germline genetic testing. Terdiman JP, et al. Gastroenterology. 2001;120(1):21-30. doi:10.1053/gast.2001.20874. PMID: 11208710.
  • Tumor microsatellite-instability status as a predictor of benefit from fluorouracil-based adjuvant chemotherapy for colon cancer. Ribic CM, et al. N Engl J Med. 2003;349(3):247-57. doi:10.1056/NEJMoa022289. PMID: 12867608.
  • Systematic review of microsatellite instability and colorectal cancer prognosis. Popat S, et al. J Clin Oncol. 2005;23(3):609-18. doi:10.1200/JCO.2005.01.086. PMID: 15659508.
  • Use of microsatellite instability and immunohistochemistry testing for the identification of individuals at risk for Lynch syndrome. Baudhuin LM, et al. Fam Cancer. 2005;4(3):255-65. doi:10.1007/s10689-004-1447-6. PMID: 16136387.
  • Sargent DJ, Marsoni S, Monges G, Thibodeau SN, Labianca R, Hamilton SR, French AJ, Kabat B, Foster NR, Torri V, Ribic C, Grothey A, Moore M, Zaniboni A, Seitz JF, Sinicrope F, Gallinger S. 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):3219-26. doi:10.1200/JCO.2009.27.1825. Epub 2010 May 24. PMID: 20498393.
  • Microsatellite instability testing and its role in the management of colorectal cancer. Kawakami H, et al. Curr Treat Options Oncol. 2015;16(7):30. doi:10.1007/s11864-015-0348-2. PMID: 26031544.
  • Le DT, Durham JN, Smith KN, Wang H, Bartlett BR, Aulakh LK, Lu S, Kemberling H, Wilt C, Luber BS, Wong F, Azad NS, Rucki AA, Laheru D, Donehower R, Zaheer A, Fisher GA, Crocenzi TS, Lee JJ, Greten TF, Duffy AG, Ciombor KK, Eyring AD, Lam BH, Joe A, Kang SP, Holdhoff M, Danilova L, Cope L, Meyer C, Zhou S, Goldberg RM, Armstrong DK, Bever KM, Fader AN, Taube J, Housseau F, Spetzler D, Xiao N, Pardoll DM, Papadopoulos N, Kinzler KW, Eshleman JR, Vogelstein B, Anders RA, Diaz LA. Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade. Science. 2017;357(6349):409-413. doi:10.1126/science.aan6733. Epub 2017 Jun 08. PMID: 28596308.
  • Overman MJ, Lonardi S, Wong KYM, Lenz HJ, Gelsomino F, Aglietta M, Morse MA, Van Cutsem E, McDermott R, Hill A, Sawyer MB, Hendlisz A, Neyns B, Svrcek M, Moss RA, Ledeine JM, Cao ZA, Kamble S, Kopetz S, André T. 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. doi:10.1200/JCO.2017.76.9901. Epub 2018 Jan 20. PMID: 29355075.
  • 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 April 11, 2023. Available at www.ncbi.nlm.nih.gov/books/NBK1211/
Is research allowed on the sample after clinical testing is complete? Help
Research testing is only performed under IRB approved protocol with an opt-out policy in place.
Recommended fields not provided:
Technical Information
Test Procedure: Help
The Idylla is a fully-automated real-time polymerase chain reaction based molecular testing system that uses formalin-fixed, paraffin-embedded slides. This assay detects a novel panel of 7 monomorphic biomarkers (ACVR2A, BTBD7, DIDO1, MRE11, RYR3, SEC31A, SULF2) to evaluate microsatellite instability status without need for normal (noncancerous) tissue from each patient.(Package insert: … View more
Availability: Help
Tests performed
Entire test performed in-house
Analytical Validity: Help
A total of 100 accuracy samples were run retrospectively during verification; 55/100 samples were colorectal, 41/100 were endometrial, and the remaining 4/100 were other tumor types. The overall concordance between the Idylla and Promega results was 98/100 (98%). Seventy-nine of 100 samples were microsatellite stable (MSS) by Promega and 77 … View more
Assay limitations: Help
The finding of tumor microsatellite instability does not distinguish between somatic and germline alterations. Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given to us is inaccurate or incomplete.
Proficiency testing (PT):
Is proficiency testing performed for this test? Help

Method used for proficiency testing: Help
Formal PT program

PT Provider: Help
College of American Pathologists, CAP

Description of PT method: Help
CAP Vended
Recommended fields not provided:
Regulatory Approval
FDA Review: Help
Category: FDA exercises enforcement discretion
Additional Information

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