Question 1

What does it mean for colorectal cancer to be MSI-high or "mismatch repair deficient"?

Accepted Answer

Cells normally have a built-in proofreading system, called mismatch repair, that fixes errors when DNA is copied. In a small subset of colorectal cancers, that proofreading system breaks down, and these tumours are called mismatch repair deficient (dMMR). They accumulate so many DNA errors that they become highly visible to the immune system. The lab signature of this is called microsatellite instability-high, or MSI-high. MSI-high status is one of the most important biological features in colorectal cancer research, particularly for immunotherapy.

Question 2

What are KRAS and BRAF mutations in colorectal cancer?

Accepted Answer

KRAS and BRAF are genes that act like switches inside cells, telling them when to grow. Specific changes in these genes are common in colorectal cancer and lock the switch in the "on" position, fuelling cancer growth. Each mutation defines a distinct subtype with its own biology and is the focus of separate areas of research, particularly in classes of treatment called targeted therapy.

Question 3

Why are rectal cancer and colon cancer studied separately?

Accepted Answer

Although rectal cancer and colon cancer both arise from the lining of the large bowel, the two sit in different parts of the body and are treated differently. Surgery is more complex for rectal cancer, and radiation plays a much larger role. Because of these differences, research is often split: rectal cancer studies frequently look at organ-preservation strategies and combinations of chemotherapy and radiation, while colon cancer research focuses on after-surgery treatment and targeted approaches in advanced disease.

Colorectal Cancer clinical trials in Australia

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Colorectal Cancer clinical trials: common questions

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