Colon Cancer Testing: What To Ask
- Knowing which questions to ask regarding colon cancer testing is important as the field continues to evolve and grow with more testing options becoming available.
- Some inherited DNA mutations can be passed from generation to generation and predispose a carrier to an increased risk of cancer in certain organs. This can be tested with germline testing.
- People are recommended to undergo germline testing when they meet specific requirements based on their personal and family history.
- Testing of the tumor itself is performed to help guide treatment options and tailor therapy. This is called somatic testing.
- MMR/MSI testing is performed on almost all new diagnoses of colon cancer, while other mutations are tested when a patient develops metastatic disease.
- Most testing is covered by insurance. However, coverage can vary based on the specific insurance.
- If you feel you are a candidate for additional testing for inherited genetic mutations or testing of your cancer itself, do not hesitate to ask your healthcare team.
As you make decisions regarding your treatment and additional testing that can be performed with your colorectal cancer, it is important to discuss these options with your doctor and the rest of your healthcare team and ask questions when topics aren’t clear.
Read MoreDoes my colon cancer put my family members at greater risk?
Specific genes or mutations in DNA can be inherited and passed down from parents to children. Specific warning signs or factors in your personal or family history could point to your colon cancer being caused by an inherited DNA mutation.These factors include but are not limited to:
- A personal or family history of multiple colon polyps
- A personal diagnosis of colon cancer at a young age (<50 years old)
- A personal or family history of multiple cancers diagnosed in one individual
- A family history of cancer diagnosis at a young age (<50 years)
- A family history of multiple people with a cancer diagnosis,
Is there any additional testing that needs to be done to understand the risk?
If there is a concern you might have an inherited cancer-causing DNA mutation, you will typically be referred for genetic counseling, undergo additional questioning and a more extensive look into your personal and family history, and undergo germline testing if indicated.
Germline testing looks at your DNA for a variety of known inherited DNA mutations that can cause cancer. Negative results let you know there is likely not an increased risk of developing cancer from an inherited DNA mutation.
If positive, it can prompt additional testing by family members. If they are also carriers of this DNA mutation, it allows them to be proactive and undergo early screening of potential cancers they are more at risk of developing, ideally catching them at earlier stages making curative treatment more effective.
Common inherited mutations that are associated with an increased risk of colon cancer include Lynch syndrome (HNPCC) and familial adenomatous polyposis (FAP).
What molecular testing should I be receiving right now?
As described above, based on your family and personal history, you may qualify for additional germline testing to assess for inherited DNA mutations. In addition to germline testing, there is also testing performed on the tumor itself, known as somatic tumor testing. This looks for DNA mutations specific to colon cancer. The type of somatic tumor testing performed often depends on the stage of your disease.
All patients with a new diagnosis of colon cancer, regardless of stage, should undergo Mismatch Repair (MMR) or Microsatellite Instability (MSI) testing. This testing gives valuable information on the overall behavior of the disease. It is also important for helping guide treatment recommendations in more advanced local disease or metastatic disease that has spread to other distant sites.
Patients with metastatic colon cancer should additionally undergo testing for other potential mutations, including KRAS, NRAS, BRAF, and HER2 mutations. These also help to tailor therapy and avoid ineffective treatment options.
How are the different molecular tests performed?
Germline testing is typically done with a saliva or blood test, and normal cells from your body are then analyzed. For tumor-based somatic testing, it requires a piece of the cancer itself and requires either a biopsy or tissue from the surgery you had to make the diagnosis in the first place. Sometimes a second biopsy might be required to collect additional tissue, but that is uncommon.
Is testing covered by my insurance? What should I expect as a patient to be covered, and what might not be?
MMR/MSI testing or molecular testing of the tumor is typically covered by insurance, especially in more advanced diseases when this information is needed for treatment decisions. “In general, there may be a copay associated with it depending on the insurance, but generally it’s not as financially burdensome as a lot of other investigations,” says Dr. Eric Christenson, a Medical Oncologist at Johns Hopkins Kimmel Cancer Center who focuses on gastrointestinal malignancies.
Germline testing can be a little bit more challenging with variable coverage by insurance companies. “And so that can have an out-of-pocket cost. That’s usually on the order of several hundred dollars, although that varies, again, depending on insurance,” says Dr. Christenson.
How does molecular testing work for clinical trials? When would that be helpful?
Most ongoing clinical trials looking at targeted therapies using molecular testing are in patients with stage 4 or metastatic disease that has spread to sites outside the colon. The availability of clinical trials and the ability to enroll in these trials can depend on several factors, including where you are receiving treatment and the molecular profile of your colon cancer. If you are interested in discussing clinical trials further, please consult with your doctor and healthcare team. Although less common, there are ongoing trials for earlier-stage disease as well.
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