Cancer is the second leading cause of death in the U.S. It is also one of the most costly diseases to treat. Upon receiving a cancer diagnosis, the next step for some patients is formulating a treatment plan with their provider. For many, treatment options include chemotherapy and radiation, and while these therapies can be effective, they often come with debilitating side effects. Moreover, patients may be unable to withstand these kinds of toxic treatments long enough to decrease or eliminate the tumor or lessen their disease.
Rather than killing tumor cells like traditional chemotherapy treatments, new targeted cancer therapies act on specific cancer related molecules to block tumor cell growth. Some therapies, like chemotherapy, work through a general mechanism of action. When a precise mechanism of action is known, a treatment can be developed which ‘targets’ a particular tumor. Targeted therapies are part of a broader transformative treatment option referred to as precision, or personalized, medicine.
Precision medicine—which customizes a patient’s treatment based on factors like a person’s genomic profile and physical environment—includes testing for biomarkers. A biomarker is a biological molecule, or molecular marker, found in blood, bodily fluids and tissues. Biomarker testing identifies changes in a person’s genes or proteins, whether disease process is present or not and can identify the specific characteristics of the person's disease. Biomarker testing also provides doctors with specific information about which, if any, targeted therapies might be effective. Biomarker testing may reduce the number of adverse drug reactions a person experiences and some studies link testing to increased chances of survival.
As cancer is detected through screening or other diagnostic tools, biomarker testing provides additional information on the specific characteristics, or unique traits of the cancer. Biomarker testing can be conducted in a multitude of ways, but the most common is removing a small sample from the cancer or tumor and examining its genomic code. While some biomarkers identify just one or a few gene alterations, some can identify more than 50 alterations with a single test. In addition to cancer, biomarkers can also be used in the treatment of heart disease, multiple sclerosis, infectious disease and more.
Biomarkers are often used in clinical trials and can aid in drug discovery. Instead of relying on natural endpoints such as survival rates, biomarkers can be used as surrogates. One study, which looked at medicines approved between 2015-2019 in the United States and Europe, found approximately 65% were associated with at least one biomarker. On the other hand, some research argues against the use of biomarkers for this purpose, citing that overdependence on surrogate endpoints may lead to unsafe or ineffective treatments.
While biomarkers show great promise, balancing patient privacy with acquiring real world data for research is one concern, even with the Health Insurance Portability and Accountability Act privacy rule in place. Recognizing data privacy concerns related to biomarker testing, the federal government issued guiding principles on protecting participant privacy and promoting autonomy.
Another concern is the potential cost of biomarkers and targeted therapies. An important distinction is the price for biomarker testing and the price of any related treatments are separate and significantly different. For example, the average price for a biomarker test is $1,700, whereas the average price for drugs used in treating cancer range between $90,000 to over $300,000. While precision medicine and biomarkers are a fairly new option for patients, some research has shown biomarkers have potential to improve treatment costs.
Lastly, coverage of biomarker testing varies widely between public and private payers, and from state to state, possibly leading to disparities in access and use. One study comparing health outcomes of lung cancer patients enrolled in Medicaid to those with private insurance coverage found that people enrolled in Medicaid were less likely to receive biomarker testing—57% compared to 71%. Furthermore, they were 23% more likely to die from the disease than those with private insurance.
Evidence suggests increasing access to biomarker testing and targeted treatment may reduce these disparities. To address gaps, some lawmakers are considering mandated coverage of biomarker testing as a tool to advance health equity.