Name of the Procedure:

Microsatellite Instability Analysis (MSI analysis) Common name(s): MSI testing Technical/medical terms: Microsatellite instability analysis, markers for mismatch repair deficiency

Summary

Microsatellite Instability Analysis (MSI analysis) is a lab test that compares specific sequences of DNA in cancerous tissue to those in normal tissue from the same patient. It identifies mutations, particularly in markers like BAT25 and BAT26, to determine if there is a mismatch repair deficiency, which is often associated with hereditary non-polyposis colorectal cancer (HNPCC) and Lynch syndrome.

Purpose

The MSI analysis is used to identify genetic mutations linked to hereditary non-polyposis colorectal cancer (HNPCC) and Lynch syndrome. The goal is to diagnose these conditions, which can lead to the development of colorectal and other cancers. By identifying mismatch repair deficiencies, healthcare providers can offer more accurate prognoses and tailor treatment strategies.

Indications

• Patients with a family history of colorectal cancer
• Individuals diagnosed with colorectal cancer at a young age (typically under 50)
• Patients with multiple primary cancers, especially those associated with Lynch syndrome, such as endometrial, ovarian, or stomach cancer

Preparation

• No specific preparation is required for MSI analysis.
• Diagnostic assessments include obtaining tissue samples from both neoplastic (cancerous) and normal tissue, often through a biopsy or surgical resection.

Procedure Description

1. A pathologist examines the tissue samples under a microscope.
2. DNA is extracted from both the cancerous tissue and the normal tissue.
3. The extracted DNA is analyzed for specific markers (e.g., BAT25, BAT26) to detect any instability in microsatellite regions.
4. The results are compared to determine if there are any significant differences indicating mismatch repair deficiencies.

Tools/Equipment:

• Microscopes, DNA extraction kits, PCR equipment
• Genetic sequencers and markers for DNA analysis

Anesthesia/Sedation:

• Typically, no anesthesia or sedation is required for the analysis itself.
• Anesthesia may be used if a biopsy or surgical tissue extraction is necessary.

Duration

The analysis itself typically takes a few days to a week, depending on the laboratory's workload and the complexity of the case.

Setting

The procedure is performed in a specialized pathology or genetics laboratory.

Personnel

• Pathologists
• Geneticists
• Laboratory technicians

Risks and Complications

• There are no direct risks associated with the laboratory analysis itself.
• Complications may arise from the tissue biopsy, such as infection or bleeding, though these are generally rare.

Benefits

• Early and accurate diagnosis of Lynch syndrome and HNPCC
• Allowing for personalized treatment plans
• Better prognosis and targeted screening for patients and their family members

Recovery

• No recovery period is necessary for the analysis itself.
• If a biopsy was performed, follow standard post-biopsy care, including wound care and activity restrictions as advised by your healthcare provider.

Alternatives

• Immunohistochemistry (IHC) testing for mismatch repair proteins is an alternative.
  • Pros: Can also indicate mismatch repair deficiency, quicker results.
  • Cons: May not be as comprehensive as MSI analysis.

Patient Experience

• During the procedure: If a biopsy has already been performed, no additional intervention is needed.
• After the procedure: Minimal discomfort if only the analysis is being done. If a biopsy was done, follow the care instructions for recovery.
• Pain Management: Not typically necessary unless related to a biopsy procedure.