Microsatellite instability and colorectal cancer

Area of Science:

• Oncology
• Genetics
• Molecular Diagnostics

Background:

• Microsatellite instability (MSI) characterizes approximately 15% of colorectal cancers.
• Lynch syndrome accounts for 2%-4% of colorectal cancers and is a hereditary condition increasing risk for multiple cancers.
• Identifying Lynch syndrome enables enhanced surveillance for patients and their families.

Purpose of the Study:

• To review the literature on microsatellite instability (MSI) in colorectal cancer.
• To examine current laboratory diagnostic testing strategies for Lynch syndrome detection.

Main Methods:

• Literature review of peer-reviewed articles.
• Analysis of published guidelines from professional organizations.
• Inclusion of data from clinical laboratories performing MSI testing.

Main Results:

• Universal screening for Lynch syndrome in colorectal cancer patients is recommended.
• Preliminary screening tests can effectively identify individuals unlikely to have Lynch syndrome.
• Immunohistochemistry and polymerase chain reaction-based MSI tests demonstrate comparable clinical utility.
• BRAF and MLH1 methylation testing serve as valuable reflex tests for MLH1 defects.

Conclusions:

• Early identification of Lynch syndrome through universal screening is crucial.
• Current MSI testing methods are effective, with complementary roles for specific gene and methylation analyses.
• Emerging technologies like high-throughput sequencing are expected to influence future diagnostic algorithms.