Academy of Oncology Nurse & Patient Navigators
To help reduce the risk of medication errors, healthcare professionals who administer medication are taught the “Five Rights,” or “5Rs”—the right drug, right dose, right route, and right patient, at the right time. With the evolution of biomarkers over the decades, the right drug for the right patient at the right time is the intonation of personalized medicine. Biomarkers in oncology have been around since Henry Bence Jones identified immunoglobulin light chains in the urine of a patient with multiple myeloma. This discovery marked the beginning of research into tumor biomarkers. From oncology history, trials of an agent in patients with advanced non–small cell lung cancer (NSCLC) showed little efficacy, but later studies found higher response rates in certain patient subgroups.1 Clinical development of an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, gefitinib, demonstrated higher response rates in the patient subgroups of Asians and never-smokers who carried a higher incidence of EGFR mutations. A prime example of the right drug for the right patient at the right time.
The word biomarker is derived from “bio,” relating to life or living things, and “marker,” representing a measurable substance in an organism whose presence is indicative of disease, infection, or environmental exposure. Cancer biomarkers are any measurable biomolecules, such as alterations in an individual’s DNA, mutations or gene expression changes, proteins that are produced by cancer cells or other cells in response to cancer. Biomarkers can be found in body fluids or tissues or other molecules or substances, such as circulating tumor DNA. They can be detected in samples obtained from tissues through tumor biopsy, blood (or serum or plasma), saliva, buccal swabs, stool, urine, etc.
Biomarkers can be found in body fluids or tissues or other molecules or substances. They can be detected in samples obtained from tissues through tumor biopsy, blood, saliva, buccal swabs, stool, urine, etc.
Biomarkers can be used throughout the cancer care continuum as tools for cancer risk assessment, screening, and early detection of cancer, accurate diagnosis, patient prognosis, prediction of response to therapy, and cancer surveillance and monitoring response. They can help detect cancer at an early stage, when it is more likely to be treatable. Examples are the prostate-specific antigen blood test, which can be used to screen for prostate cancer, and CA-125 with other markers like HE4 and CA19-9 for ovarian cancer. BRCA1 and BRCA2 mutations in breast and ovarian cancer or Lynch syndrome testing for colorectal and endometrial cancer allows for early detection, risk-reducing measures (like increased surveillance or prophylactic surgeries), and tailored treatment options.
In diagnosis, biomarkers can help confirm the presence of cancer and determine the type and stage of the disease. In breast cancer, biomarkers like the estrogen receptor and HER2 are assessed to determine the type of cancer and guide treatment. Over the past few years, attention has been given to low HER2 or tumors with lower than normal levels of the HER2 protein on their surface, and this has expanded the understanding of breast cancer biology and treatment options for targeted therapies for this specific group of breast cancers. Other common diagnostic tumor profiling includes EGFR in lung, colorectal, and head and neck cancers; KRAS in colorectal, pancreatic, and lung adenocarcinoma; BRAF in melanoma and colorectal cancer; and ALK in some cases of NSCLC.
With the diagnostic signature comes the prognostic ability to predict how a cancer is likely to behave, such as how fast it will grow or spread. This gives information on the patient’s overall cancer outcome with or without standard treatment. Examples include Ki-67 in breast cancer, BRAF mutations in melanoma, and circulating tumor cells in various cancers that are strongly correlated with metastasis and a poorer prognosis.2 Chromosome 17p deletions and TP53 mutations are linked to a higher risk of death in patients with chronic lymphocytic leukemia. By understanding how a cancer is expected to act, the healthcare team can make better informed decisions on how to treat the disease.
Diagnostics and prognostics are tied into treatment selection. Biomarkers can help determine which treatments are likely to be most effective for a particular patient’s cancer. Tumor markers are not a substitute for imaging tests or biopsies, but they can provide valuable additional information. The cellular information about what is going on inside a cancer cell enables healthcare professionals to create treatment to target what is causing the cancer to grow. By tailoring treatment to the individual characteristics of a patient’s cancer, biomarker testing leads to better treatment outcomes and improved quality of life. And it helps avoid treatments that are not likely to be effective, reduces the risk of side effects, and improves the patient experience. An example is gefitinib in the paragraph above. The National Cancer Institute has an extensive list of approved targeted therapy drugs for the treatment of cancer types; some are repeated in the listing because they have been approved to treat more than one type of cancer.3
Biomarkers can be used to monitor how a cancer is responding to treatment and to detect if the cancer is returning. For example, after treatment for colon cancer, carcinoembryonic antigen is monitored to detect recurrence early that can provide a lead time of about 5 months compared with other diagnostic methods for detecting recurrence.4 Other examples include BCR-ABL gene testing for chronic myeloid leukemia and lactate dehydrogenase for malignant melanoma.
Biomarker testing is a process that involves a team approach. It centers around a pathologist to provide expert interpretation, but it requires a coordinated approach for the right test to be ordered in an efficient manner and detailed molecular findings be streamlined to the correct healthcare provider to ensure results are discussed with the patient to decide on a timely treatment plan. The Association of Cancer Care Centers (ACCC) launched BiomarkerLIVE in 2019 with the goal of improving communication about biomarkers and molecular profiling among cancer care teams.5 It includes podcasts, white papers, an assessment tool, and other resources to enrich this process for best patient care. The Journal of Oncology Navigation & Survivorship shared a 4-part video series—“Biomarkers and the Cancer Care Team: Critical Partners in Personalized Medicine”—to help healthcare professionals understand the process of biomarker testing and team expectations.6
The NCI has an extensive list of approved targeted therapy drugs for the treatment of cancer types; some are repeated in the listing because they have been approved to treat more than one type of cancer.
A precision medicine steward or a dedicated navigator can enrich the biomarker process. This person focuses on optimizing biomarker testing and care coordination related to personalized medicine approaches, often acting as a liaison between patients and the multidisciplinary team. It is a role to connect guideline-concordant testing and real-world clinical practice. In 2022, the Academy of Oncology Nurse & Patient Navigators partnered with ACCC and others to make the case for implementation of precision medicine stewards through education and awareness-building about the unique role and value of these dedicated navigators.7
It is an expanding field, and not everyone who is assessed has a marker correlated with a targeted treatment. Since some targeted treatments are only available through clinical trials, a dedicated team approach or steward is critical to connect patients to the best care.
There are many concerns as this field evolves. Biomarker testing can be expensive, and access to testing may be limited for some patients. The cost of biomarker testing can vary widely, depending on the test selected and insurance status. Some biomarker tests are covered by Medicare and Medicaid, and private insurance companies may cover the cost of a biomarker test if there is enough proof that the test is needed to guide treatment decisions. Clinical trials will cover the cost of testing for any new biomarkers.
Biomarkers hold immense promise for advancing healthcare by offering a powerful approach for improving screening, diagnostics, prognostics, treatment, and monitoring of oncology disease processes. They are a valuable tool to improve patient outcomes and response to personalized interventions. By addressing the challenges and focusing on an efficient and timely process, patients will gain the most from tailored treatments to address individual patient characteristics and disease profiles. All patients deserve the best drug at the right time for best outcomes.
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