Biomarker testing for metastatic colorectal cancer patients to create individual treatment plans
There are many treatment options
Precision medicine is advancing
Precision medicine, also known as personalized medicine, aims to individualize medical treatment plans. Medical providers can now take steps to identify patients that may be more likely to benefit—or may be at greater risk of adverse effects—from one treatment plan versus another.
Medical treatment plans for stage IV (metastatic) colorectal cancer, or mCRC, may include radiotherapy, chemotherapy, targeted therapy, and surgery, although surgery is more often an option with earlier-stage cancer. Chemotherapy and targeted therapy are the most common treatments for mCRC. Chemotherapy works by killing the rapidly dividing cells that comprise the bulk of a cancerous tumor. Unfortunately, chemotherapy is not selective and also kills normal cells.
Targeted therapy works by targeting a cancer’s unique features such as specific genes, proteins, or tissue environment that contribute to cancer growth, progression, and metastasis. Targeted therapy may be used alone or in combination with chemotherapy.
Biomarker testing can individualize your treatment
Biomarkers, short for biological markers, are biological molecules found in blood, other body fluids, or tissues that can be measured to provide information about a tumor’s characteristics. A biomarker test may offer medical providers a wealth of information, including:
Normal or abnormal cell function
Insight on the likely outcome of a cancer if it is left untreated (i.e. prognosis)
The likelihood of the cancer’s response or lack of response to a specific treatment plan (predictive)
The likelihood of severe toxicity to certain treatments (predictive)
The likelihood of tumor recurrence
Knowing your biomarker status may help you and your doctor decide on the most effective treatment plan for you, while avoiding treatments that may not work for you.
Some commonly tested biomarkers relevant to colorectal cancer are specific changes in the genes RAS* (KRAS, NRAS), BRAF, PIK3CA and changes in one of the genes involved in DNA mismatch repair (MLH1, MSH2, PMS2, MLH6) that lead to increases in microsatellite instability (MSI-H). The presence or absence of a specific biomarker could indicate a course of treatment.
According to a report from the National Comprehensive Cancer Network, changes in RAS are present in about 50 percent of mCRC patients. Patients tested for RAS mutations and whose results show no mutation/alteration in their tumor (wild type RAS) may benefit from EGFR-targeted therapy. The presence of RAS mutations often predict lack of response to EGFR-targeted therapy.
Changes in BRAF are present in about 10 to 15 percent of mCRC patients, and their presence also circumvents EGFR-directed therapy.
Changes in DNA mismatch repair could be hereditary (Lynch Syndrome) or spontaneous (in sporadic tumors). Analyzing changes in these genes can be predictive of a lack of response to fluorouridine-based therapies and, at the same time, be predictive to favorable response on immunotherapy.
Knowing your biomarker status
The genetic makeup of each patient’s tumor is unique. Knowing your biomarker status—the genetic characteristics of your tumor—may help you and your doctor select an appropriate treatment plan.
When you’re diagnosed with metastatic colorectal cancer (mCRC), you and your doctor want to get as much information as possible to make appropriate health care decisions. It’s important to know your tumor biomarkers early in treatment. When you understand your disease and how it affects your body, you can team up with your doctor to manage your treatment plan.
As a patient with mCRC, you and your caregivers are encouraged to keep an open dialogue with your doctors to stay current on genetic and biomarker testing and what it could mean for your treatment plan.
Speaking with your doctor about biomarkers
It’s important to discuss biomarkers with your doctor. Here is some guidance to help:
Talk to your doctor about biomarker testing soon after your diagnosis of mCRC so that you can make an informed decision regarding treatment plans.
Ask your doctor whether your tumor has been tested for biomarkers:
If yes: What is your biomarker status for each of these biomarkers?
If no: Will your tumor be tested and when?
Ask your doctor how your biomarker status will affect your treatment plan.
Putting it all together
Advancements in precision (personalized) medicine now let patients get tested for biomarkers. These tests lead to important discussions with medical providers. Knowing your biomarker status may help you and your doctor make important health care decisions and optimize your treatment plan. Several biomarkers—identified as RAS* (KRAS, NRAS), BRAF, PIK3CA, MLH1, MSH2, PMS2, MLH6—may be important to your mCRC diagnosis. Speak with your doctor about your biomarker status.