Genomic Testing

Gene profile testing, which is done by microarray assay or reverse transcription-polymerase chain, is done for colon and rectum cancers. For Colon and Rectum, there are several Genomic testing data items. These are called Site-Specific Data Items (SSDIs), and are collected for each case.

See Schemas | SSDI and Grade Data for the SSDI manual and the schema information or SEER*RSA in the Colon and Rectum schema for complete coding instructions for these data items.

Note: For the SSDIs, it is very important that you read the general instructions (see NAAACR link above) first. For example, the general instructions tell you how to code when there is a range, when “less than” or “greater than” is used. After the general instructions are reviewed, you move to the data specific instructions.

More information for these SSDIs can be found in the SSDI Manual.

BRAF Mutational Analysis

BRAF is a specific mutation that makes a protein that sends signals to cells to grow. This mutation is found in Colorectal cancer, along with several other cancers.

BRAF status may help to plan cancer treatment.

BRAF is usually for patients with metastatic disease. The results from BRAF testing may be found on a molecular pathology report, which may be an addendum to the pathology report.

If there is no mention of BRAF in the record, code unknown.

KRAS and NRAS Mutational Status

KRAS and NRAS are important signaling intermediates in the growth receptor pathway, which controls cell proliferation and survival. Both KRAS and NRAS may be constitutively activated through mutation during colorectal carcinogenesis so that they continuously stimulate cell proliferation and prevent cell death (reference AJCC 8, pg. 266).

KRAS and NRAS mutations predict poor response to anti-EGFR therapy in patients with metastatic colon cancer. AJCC 8 estimates that KRAS may be activated in up to 40% and NRAS in about 7% of colorectal carcinomas.

KRAS and NRAS testing is recommended for patients with metastatic disease. The results from KRAS and NRAS testing may be found on a molecular pathology report, which may be an addendum to the pathology report.

KRAS and NRAS status may help to plan cancer treatment.

If there is no mention of KRAS or NRAS in the record, code unknown.

Microsatellite Instability

The microsatellite instability (MSI) test is a genetic test performed on tumor tissue to look for differences in length of certain non-functioning sections of DNA. The differences are caused by problems with the genes that encode proteins that normally repair certain types of DNA damage.

A high proportion of colon cancers arising in patients with hereditary nonpolyposis colorectal cancer (HNPCC) (also known as Lynch syndrome) have high MSI and a smaller percentage of colon cancers not associated with Lynch syndrome have high MSI.

Patients with high MSI colon cancer may be tested further to determine if they have HNPCC. In addition, MSI is a useful prognostic marker in that patients with high MSI colon cancers have better response to surgery and survival.

MSI status may help to plan cancer treatment. A large proportion of colon cancers with high MSIs arise in patients with hereditary nonpolyposis colorectal cancer (HNPCC) (also known as Lynch syndrome); while a smaller percentage of colon cancers not associated with Lynch syndrome may also have a high MSI.

MSI is usually only tested on invasive neoplasms.

If there is no mention of MSI in the record, code unknown (this includes in situ neoplasms)

Updated: June 24, 2025