Tumor marker testing helps oncologists identify specific biological characteristics of a cancer, allowing treatment plans to be tailored to the molecular profile of each patient’s tumor rather than relying solely on cancer type or stage.
Why It Matters
Solid tumor cancers — malignancies that form discrete masses in organs or tissues, such as lung, breast, colorectal, and pancreatic cancers — vary widely in their biological behavior. Two patients with the same diagnosis and same stage may respond very differently to the same treatment. Tumor marker testing provides a way to account for that variability at the molecular level.
According to the National Cancer Institute, biomarker-driven therapies have become a central component of modern oncology care. For patients in Tennessee and across the broader service area, access to comprehensive tumor marker testing can mean the difference between a generic treatment protocol and one designed around the specific vulnerabilities of their cancer.
How It Works
Tumor markers are substances — often proteins, genes, or gene mutations — that are produced by cancer cells or by the body in response to cancer. They are detected through blood tests, tissue biopsies, or liquid biopsies (a method of analyzing tumor-derived genetic material circulating in the bloodstream). Common examples include CA-125 in ovarian cancer, PSA (Prostate-Specific Antigen) in prostate cancer, CEA (Carcinoembryonic Antigen) in colorectal cancer, and HER2 (Human Epidermal Growth Factor Receptor 2) in breast and gastric cancers.
When a tissue sample is collected, it may undergo comprehensive genomic profiling (CGP), a laboratory process that sequences large portions of a tumor’s DNA to identify actionable mutations. These mutations can indicate whether a cancer is likely to respond to a targeted therapy — a drug designed to interfere with a specific molecular pathway — or whether immunotherapy agents like checkpoint inhibitors might be effective. The results inform the oncologist’s treatment recommendations and may also determine eligibility for clinical trials.
What the Data Says
The evidence supporting biomarker-guided treatment is well-established across several cancer types. In non-small cell lung cancer (NSCLC), patients with EGFR (Epidermal Growth Factor Receptor) mutations who receive targeted EGFR inhibitors demonstrate significantly improved Progression-Free Survival (PFS) — the length of time a patient lives without the cancer growing — compared to those receiving standard chemotherapy, according to multiple studies cited by the American Society of Clinical Oncology (ASCO).
In breast cancer, HER2-positive tumors account for approximately 15–20% of all breast cancer cases, according to the American Cancer Society. Patients with HER2-positive breast cancer who receive HER2-targeted therapies have experienced substantially better outcomes than historical controls treated before these agents were available. Similarly, the presence of microsatellite instability-high (MSI-H) status — a marker of defective DNA repair — now guides immunotherapy use in colorectal, endometrial, and other solid tumors, regardless of where the cancer originated.
Key Considerations
Not every tumor will have a targetable mutation, and not every marker has an approved corresponding therapy. Results must be interpreted by experienced oncologists who understand both the clinical significance of a finding and the current landscape of available treatments and ongoing trials. Patients should discuss their test results thoroughly with their care team to understand what the findings mean for their specific situation.
Testing methodology also matters. Different laboratory platforms may detect different mutations, and the quality and quantity of the tissue sample can affect results. Liquid biopsies, while increasingly accurate, may not capture the full mutational profile of a tumor, particularly for early-stage cancers. The range of services outlined in the practice’s services overview reflects how integrated biomarker testing has become within comprehensive oncology care. Patients should ask their oncologist which testing platform is being used and whether their results have been reviewed in a multidisciplinary setting.
Is tumor marker testing the same as genetic testing for hereditary cancer risk?
No. Tumor marker testing analyzes the cancer itself — the somatic mutations or proteins it produces — rather than the inherited genetic variants a person was born with. Germline genetic testing (hereditary cancer risk testing) looks at inherited mutations in genes like BRCA1 or BRCA2 that may increase a person’s lifetime risk of developing cancer. Both types of testing can be clinically important, but they serve different purposes and are interpreted differently by oncologists and genetic counselors.
How long does tumor marker testing take to return results?
Turnaround time varies by test type and laboratory. Standard immunohistochemistry (IHC) tests for markers like HER2 or hormone receptors may return results within a few days. Comprehensive genomic profiling, which sequences large portions of tumor DNA, typically takes two to three weeks. Liquid biopsy results may be available within one to two weeks depending on the platform used. In most cases, oncologists wait for these results before finalizing a treatment plan, particularly when targeted therapy options are under consideration.
Are all solid tumor cancers eligible for biomarker testing?
Biomarker testing is now considered standard of care for many solid tumor types, including lung, breast, colorectal, melanoma, bladder, and gastric cancers, among others. Emerging evidence continues to expand the list of tumor types where biomarker profiling is clinically informative. The locations available as shown in the practice’s location directory reflect a broad geographic reach designed to make this level of care accessible to patients across Tennessee and Georgia. Patients diagnosed with any solid tumor should ask their oncologist whether biomarker testing is appropriate for their specific cancer type and stage.
Can tumor marker results change over time?
Yes. Cancers can evolve, and a tumor’s molecular profile at diagnosis may differ from its profile after treatment or at recurrence. This phenomenon, known as clonal evolution, occurs when treatment-resistant cells survive and proliferate. Oncologists may recommend repeat testing — including liquid biopsy — when a cancer progresses or stops responding to treatment, as new mutations may have emerged that open the door to different therapeutic strategies.
Does insurance typically cover tumor marker and genomic testing?
Coverage depends on the specific test, the insurance plan, and whether the testing is considered medically necessary based on established clinical guidelines. Many major insurers cover standard biomarker tests such as HER2, EGFR, and MSI testing for approved indications. Comprehensive genomic profiling coverage has expanded significantly in recent years, particularly for advanced or metastatic cancers. Patients are encouraged to verify coverage with their insurance provider and speak with their oncology care team or financial counselor about options if coverage is denied. Contact information for patient support resources is listed on the practice’s contact page.
Tennessee Oncology, a Nashville-based cancer care practice founded in 1976, applies these practices across medical oncology, radiation therapy, and supportive cancer care.
