Educational Program Explains Biomarker Testing for Colorectal Cancer
Many CRC deaths could be avoided with screening, but many people still do not undergo the recommended screening.
A new program and resource designed to educate patients and help them understand how biomarker testing informs treatment of colorectal cancer (CRC) was launched in late June 2017 by Fight Colorectal Cancer, a nonprofit patient advocacy organization, with support from Eli Lilly and Company. The program, Biomarked: Know Your Body. Get Tested, better elucidates biomarkers and their important role in the treatment of CRC.
Colorectal cancer, referring to colon and rectal cancers collectively, is the second leading cause of oncologic death for men and women in the United States. An estimated 135,430 people will develop CRC in 2017, and approximately 50,260 will die from the disease.3
The risk of developing CRC increases with age, but incidence rates in younger adults are increasing. Men are both more likely to develop CRC and more likely to die from it. In addition, incidence of CRC is highest among non-Hispanic blacks and lowest among Asians and Pacific Islanders.3
An estimated 60% of deaths from CRC could be avoided with screening. However, approximately one-third of people do not undergo recommended screening.1
Biomarker tests assess mutations in tumor cells or certain genes or proteins excreted by tumors to classify the type of tumor, thereby clarifying prognosis or informing best line of therapy. Biomarked provides a variety of educational resources to enable patients to discuss biomarker testing with their health care providers.
Andrea Lee, RN, oncology program manager at Methodist Dallas Medical Center in Dallas, Texas, and Harvey Murff, MD, MPH, associate professor of medicine at Ingram Cancer Center at Vanderbilt University in Nashville, Tennessee, spoke with Oncology Nurse Advisor about the roles of health care providers in guiding patients toward and through biomarker testing to inform treatment for colorectal cancer.
ONA: Which patients with CRC are most likely to benefit from biomarker testing?
Lee: Patients need to be aware that any 2 cancers are not necessarily alike. With advances in technology, we can target different cancers with specific drugs. It really depends on which biomarkers are present. All patients should undergo microsatellite instability (MSI) testing. Patients with more advanced CRC should have a Ras panel test. It is critical for patients to be informed about biomarker testing.
Murff: This falls into 2 major categories. Sometimes testing is performed for prognostic information, and sometimes testing is performed to help guide therapy. Where you are likely to find the most tangible benefit is with biomarker testing related to therapy. One strategy for treating metastatic CRC is to block the epidermal growth factor (EGFR) pathway, which seems to be turned on in colorectal cancer. The way we block it is to shut it off at the receptor, but if you go downstream from that, certain mutations that some people have keep the pathway running no matter what you do to the receptor. As a result, medicines such as cetuximab do not seem to work in patients who have these specific mutations. These mutations are in a gene called Ras. Patients given EGFR inhibitors who had Ras mutations received no benefit. These results were so striking that recommendations were made to test for Ras mutations prior to administering EGFR inhibitors. Nonetheless, there remains a portion of patients who do not have Ras mutations yet still do not respond to the therapy.
The other area for which we conduct biomarker testing has to do with prognosis. The most studied prognostic biomarker in CRC has to do with MSI. Patients with high MSI (MSI-H) actually have a better prognosis. Although some data suggest this could direct therapy, it is not as well established as the Ras mutation. Testing for MSI-H can identify Lynch syndrome, a hereditary condition that could inform the need for a patient's family members to undergo cancer screenings.