Which is considered a feature of an MSI-H colon cancer?
The colorectal cancer (CRC) patients with microsatellite instability (MSI) have distinct clinicopathological characteristics consisting of factors predicting positive and negative outcomes, such as a high lymph node harvest and poor differentiation.
What is microsatellite instability in colorectal cancer?
Microsatellite instability (MSI) is the molecular fingerprint of a deficient mismatch repair system. Approximately 15% of colorectal cancers (CRC) display MSI owing either to epigenetic silencing of MLH1 or a germline mutation in one of the mismatch repair genes MLH1, MSH2, MSH6 or PMS2.
What is a microsatellite instability?
A change that occurs in certain cells (such as cancer cells) in which the number of repeated DNA bases in a microsatellite (a short, repeated sequence of DNA) is different from what it was when the microsatellite was inherited.
What is the main histological type of colon cancer?
The most common form of colon cancer is adenocarcinoma, constituting between 95% to 98% of all cases of colorectal cancer. Other, rarer types include lymphoma, adenosquamous and squamous cell carcinoma.
What is microsatellite instability-high MSI-H?
Describes cancer cells that have a high number of mutations (changes) within microsatellites. For example, microsatellite testing that shows mutations in 30% or more microsatellites is called microsatellite instability-high. Microsatellites are short, repeated sequences of DNA.
What is microsatellite instability testing?
Microsatellites are regions of repeated DNA that change in length (show instability) when mismatch repair is not working properly. MSI testing looks at the length of certain DNA microsatellites from the tumor sample to see if they have gotten longer or shorter as a measure of instability.
What is a microsatellite stable tumor?
In some cancer patients, the MMR process works well. For these people, the cancer cells are proficient in mismatch repair (pMMR) and their tumor cells have the same number of repeats as. in their healthy cells. This is also referred to as microsatellite stable or MSS.
How is microsatellite instability measured?
Microsatellite instability testing is used to identify tumors caused by defective MMR by comparing the number of nucleotide repeats in a panel of microsatellite markers in normal tissue with the number from tumor tissue from the same individual.
What are the different types of colorectal cancer?
Types of Colorectal Cancer
- Adenocarcinoma. Adenocarcinomas are tumors that start in the lining of internal organs.
- Gastrointestinal Stromal Tumors (GIST)
- Lymphoma.
- Carcinoids.
- Turcot Syndrome.
- Peutz-Jeghers Syndrome (PJS)
- Familial Colorectal Cancer (FCC)
- Juvenile Polyposis Coli.
What does MSI-low mean?
CRCs can be classified into 3 groups according to the MSI status: MSI-high (MSI-H), which exhibit ≥ 30 to 40% microsatellite marker instability, MSI-Low (MSI-L), which exhibit instability at < 30 to 40% of loci, and microsatellite stable (MSS), which exhibit no unstable markers. 1.