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Colorectal Cancer

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If you or someone you know has been diagnosed with colorectal cancer which is shown by a laboratory test to be MSI-H/dMMR, you may be trying to learn as much as possible about the disease and its treatments. MSI-H is short for MicroSatellite Instability-High. dMMR is short for deficient MisMatch Repair. Read on to find out more.

The information on this website should be discussed with your healthcare professional and does not replace their advice.

An icon representing colorectal cancer

What is colorectal cancer?

Colorectal cancer is cancer in any part of the colon or rectum (large bowel).

Other names for colorectal cancer include colon cancer or rectal cancer. You may also hear people use the term bowel cancer.

The colon and the rectum are one of the last parts of the digestive system. Cancers in these areas can start as a growth on the inner lining of the colon or rectum. These growths are called polyps.

Colorectal cancer usually occurs in people older than 50, however it can start at any age.

An icon representing DNA

What is MSI-H/dMMR?

MSI-H/dMMR are biomarkers that can be found in many different types of cancer, including colorectal cancer.

For more information on MSI-H/dMMR cancer click here.

Treatment with KEYTRUDA® (pembrolizumab)

Your doctors will plan your treatment according to your individual circumstances. These include the type of cancer, tumour, growth, test results, your expected response to treatment, your age and medical history.

KEYTRUDA is an immunotherapy that may be used as the first treatment in adults to treat colorectal cancer that has spread or cannot be removed by surgery (advanced cancer) and has been shown by a laboratory test to be MSI-H or dMMR.

KEYTRUDA may also be used in adults and children to treat advanced colorectal cancer which has been shown by a laboratory test to be MSI-H or dMMR, and who have received other treatments which have not worked or are no longer working.

Talk to your doctor to see if KEYTRUDA may be right for you.

KEYTRUDA is not funded in New Zealand for the treatment of patients with MSI-H/dMMR colorectal cancer.


Expand for more information on terms and definitions related to MSI-H/dMMR colorectal cancer.

Terms you may find useful:

A molecule found in our blood, body fluids, or tissues, which can tell us if something normal or abnormal is happening in our body, or if we have a certain condition or disease.

The main part of the large bowel.

Gastrointestinal (GI) tract
The passage that food travels through from the mouth to the anus.

A doctor who specialises in treating cancer with drug therapies – for example, chemotherapy and immunotherapy.

A growth inside the colon or on another body surface.

The expected outcome of your cancer. Your doctor is the best person to ask about your prognosis, but it is not possible for anyone to predict the exact course of cancer.

The last part of the large bowel before the anus.

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Questions to ask your doctor

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Patient Resources


National Cancer Institute. NCI Dictionary of Cancer Terms. MSI-H cancer.
Available at:
Accessed on 17/12/2019

National Cancer Institute. NCI Dictionary of Cancer Terms. Mismatch repair deficiency.
Available at:
Accessed on 17/12/2019

Cancer Council Australia. 2021. Understanding Bowel Cancer. A guide for people with cancer, their families and friends.
Available at:
Accessed on 15/10/2023

National Cancer Institute. NCI Dictionary of Cancer Terms. Biomarker.
Available at:
Accessed on 17/12/2019


KEYTRUDA Consumer Medicine Information

NZ-KEY-00874. TAPS DA 2339KN TAPS NP20132. First Issued February 2024.