Providing Actionable Answers and Risk Assessment for Colorectal Cancer
Colorectal cancer (CRC) is the third most common form of cancer in the U.S., with more than 150,000 new cases diagnosed each year. While sporadic colon cancers are more common, hereditary colon cancers are also frequent, and identification of these affects screening recommendations both for the individual and family members.
Fewer than half the people found to have colorectal cancer are diagnosed at an early stage, when treatment is most effective. New therapies can reduce tumor size and prolong life, but they can also be costly and not work as intended. The results and interpretations from our laboratories provide clinically actionable results to guide treatment selection, ensuring every patient receives the medication most appropriate for care. In addition to guiding treatment, our testing also assesses risk for developing hereditary cancer syndrome.
Guiding Treatment Through Clinically Actionable Results
Anti-EGFR Targeted Therapy
Monoclonal antibodies against the EGFR, such as cetuximab and panitumumab, can block the growth and spread of cancer. However, studies have shown that tumors with specific gene mutations will not respond to these therapies. Because of the potential for increased toxicity and cost, identification of individuals most likely to respond to targeted therapies is essential for appropriate patient management. Our panel was designed to meet current guidelines and remain targeted enough to provide clinically actionable results. The panel provides optimized testing for CRC patients by sequencing all clinically relevant exons in KRAS, NRAS, HRAS, and BRAF.
While tumor testing is preferable, cell-free DNA (cfDNA) testing on peripheral blood is available for colorectal cancer patients when tumor is unavailable. Our cfDNA assay will detect the presence of common KRAS mutations at codons 12, 13, 61, and 146.
- RAS/RAF Targeted Gene Panel by Next-Generation Sequencing, Tumor (Mayo ID: RASFP)
- Cell-Free DNA KRAS 12, 13, 61,146, Blood (Mayo ID: KRASD)
RAS/RAF Targeted Gene Panel [A Test in Focus]
Anti-PD-L1 immunotherapies such as pembrolizumab have recently emerged as a therapeutic option in colorectal cancer. These therapies are designed to block the PD-L1/PD-1 immune checkpoint pathway thereby assisting the immune system in tumor cell detection. However, current data indicates that only patients with defective-mismatch repair (MMR) and/or high-microsatellite instability (MSI) are likely to benefit from this therapy.
An Algorithmic Approach to Hereditary Colon Cancer Testing
While sporadic colorectal cancer is relatively common in the general population, colorectal cancer can also be due to hereditary factors. Lynch syndrome, an autosomal dominant cancer syndrome, is associated with germline mutations in the MLH1, MSH2, MSH6, PMS2, and/ or EPCAM genes. While not diagnostic, high-MSI and/or defective-MMR are considered hallmark features of Lynch syndrome. The results from MSI and MMR testing will identify patients for whom further testing, including germline sequencing, is appropriate.
Diagnosis of Lynch syndrome is complex and requires several tests often times leading to confusion over which test should be ordered when. Our algorithmic approach aids with the ordering process and guides physicians to ensure the right tests are being ordered at the right time for patients.
- Mismatch Repair (MMR) Protein Immunohistochemistry Only, Tumor (Mayo ID: IHC)
- Lynch Syndrome Panel (Mayo ID: LYNCH)
- MLH1 Hypermethylation and BRAF Mutation Analysis, Tumor (Mayo ID: BRMLH)
Testing for Non-Colorectal GI Tumors
Gastrointestinal Stromal Tumors (GIST)
This test is a single assay that uses formalin-fixed paraffin-embedded (FFPE) tissue to assess for common mutations in the KIT and PDGFRA genes, which are present in 85–90% of GIST tumors. The simplified results of this test can be useful for assessing prognosis and guiding treatment. Because of the prevalence of these mutations, this assay not only confirms the diagnosis of GIST but guides important decisions on therapy selection.
- HER2, Gastric/Esophageal, Semi-Quantitative Immunohistochemistry, Manual (Mayo ID: HERGM)
- HER2 Amplification Associated with Gastroesophageal Cancer, FISH, Tissue (Mayo ID: H2GE)
- Programmed Death-Ligand 1 (PD-L1) (22C3), Semi-Quantitative Immunohistochemistry (Mayo ID: 22C3)
- NTRK Gene Fusion Panel, Tumor (Mayo ID: NTRK)
- FGFR2 (10q26.1) Rearrangement, FISH, Tissue (Mayo ID: FGFR2)
- Biliary Tract Malignancy-Cytology, FISH (Mayo ID: FBILM)
New Test Options for NTRK Gene Fusions