NCCN Guidelines for Patients
Rectal Cancer, Version 1.2017
absence of Lynch syndrome. They are found in about
15 out of every 100 rectal cancers (15%) without
Testing for loss of MMR proteins or MSI is advised
for all people with colon or rectal cancer. These
features may affect your treatment plan. There are
two tests that can be done.
eaction) is a test that can
assess for MSI. The test consists of a process in
which millions of copies of a DNA part are made.
The copies will be examined for 5 MSI markers.
Tumors can be rated as MSS (
ow), and MSI-H
igh). MSI-H is defined
as the presence of 2 or more MSI markers. MSI-H
suggests dMMR but more testing is needed to
An IHC (
hemistry) panel is used
to assess MMR proteins. It involves applying a
chemical marker to cells then looking at them with a
microscope. There are four types of MMR proteins.
They are MLH1, MSH2, MSH6, and PMS2. If all are
present, it is unlikely that any MMR gene is mutated.
If the MLH1 protein is missing, more testing should
follow. The cancer may be tested for a BRAF V600E
mutation or a modified MLH1 gene. If a BRAF
mutation or modified gene is present, you don’t have
Lynch syndrome. If not present or the other MMR
proteins are missing, the cancer will be tested for
MMR mutations to confirm Lynch syndrome.
A medical history is a report of all health events
in your lifetime. It will include questions about
your family’s health to help assess if you have
a syndrome related to rectal cancer. Such
syndromes include Lynch syndrome and FAP.
Your doctor will examine your body for signs of
disease. He or she will touch parts of your body
to see if anything feels abnormal.
Blood tests may be done to look for signs of
cancer spread to distant sites.
Imaging tests allow your doctor to see how far
the cancer has spread without cutting into your
A biopsy is advised when surgery is an option.
A needle biopsy may be done to test for cancer
in distant sites.
Molecular testing for MSI or missing MMR
proteins is advised for all rectal cancers. Testing
advised for metastatic cancer.