New Hope Treating MSI-H Locally Advanced Rectal Cancer

MSI-H Locally Advanced Rectal Cancer refers to rectal cancer that is locally advanced and exhibits Microsatellite Instability-High (MSI-H), a genetic abnormality caused by defective Mismatch Repair Genes (MMR). This instability leads to abnormal cancer cell growth and division.

Significance of MSI-H in Rectal Cancer

MSI-H is commonly found in patients with a family history of cancer, such as Lynch Syndrome.
Patients with MSI-H often respond better to Immunotherapy compared to conventional treatments.
This cancer type has numerous mutations, making it easier for the immune system to detect and destroy cancer cells.

Treatment Options for MSI-H Locally Advanced Rectal Cancer

1. Immunotherapy

A highly effective treatment for MSI-H cancer using Immune Checkpoint Inhibitors, such as:
Medicines in the group Immune Checkpoint Inhibitors
- Pembrolizumab (Keytruda) is a commonly used drug for this treatment.
- Nivolumab (Opdivo)
- Dostarlimab (Jemperli)
These drugs can significantly shrink tumors and, in some cases, eliminate the need for surgery.

2. Standard Treatment

Neoadjuvant Chemoradiotherapy: Radiation combined with chemotherapy to shrink the tumor before surgery.
Surgery
- Total Mesorectal Excision (TME): Removal of the rectum and surrounding tissue.
- Local Excision: For small, non-invasive tumors.

3. Non-operative Management (Watch and Wait)

Patients who respond well to Immunotherapy may follow a "Watch and Wait" strategy, closely monitoring the tumor without surgery.

Advantages of Immunotherapy in MSI-H Rectal Cancer

Tumor Reduction or Elimination: Potentially avoiding surgery.
Fewer Side Effects: Compared to chemotherapy and radiation (e.g., diarrhea, inflammation).
Lower Recurrence Risk: Enhancing immune response to destroy remaining cancer cells.

MSI-H Locally Advanced Rectal Cancer responds exceptionally well to Immunotherapy, especially with Immune Checkpoint Inhibitors. This treatment approach can reduce tumor size and, in some cases, eliminate the need for surgery, offering patients a promising path to recovery.