Decoding Cancer: How Biomarkers Are Personalizing Treatment

Cancer treatment is becoming increasingly personalized, and biomarkers – unique signatures that provide insight into specific cancers – are the main driving force. 

Physicians and researchers are now able to learn far more about a person’s tumor than ever before- sometimes down to the specific gene mutations or proteins driving the cancer’s growth. This information, known as biomarker testing or molecular profiling, is helping physicians choose treatments that are more targeted, more effective, and less toxic. 

“Biomarkers are essentially biological clues that help answer important questions about a cancer,” says Linda Wu, MD, medical oncologist and clinical trialist specializing in the treatment of gastrointestinal malignancies at Columbia University Irving Medical Center. “They help us understand how a tumor behaves and what treatments may work best.” 

What are cancer biomarkers? 

Cancer biomarkers are genes, proteins, or other biological substances that provide information about a person’s cancer. They can reveal how aggressive a cancer may be, whether it is likely to respond to certain therapies, or whether it has a higher chance of returning after treatment. Some biomarkers are found directly in tumor cells, while others may be detected through blood tests or other laboratory testing. This process can be referred to in different ways, including tumor testing, genomic profiling, molecular testing, next-generation sequencing (NGS), or tumor subtyping. 

Even when two patients have the same type of cancer, their tumors may behave very differently. Biomarker testing helps clinicians understand the unique biology of each individual cancer. For many patients, biomarker testing has become a standard part of treatment planning. Some biomarkers can predict whether targeted therapies or immunotherapies are likely to work, helping patients avoid treatments that may be less effective or cause unnecessary side effects. 

How biomarker testing works 

Biomarker testing is usually performed using a sample of tumor tissue collected during a biopsy or surgery. For blood cancers, samples may come from the blood or bone marrow. Increasingly, doctors are also using “liquid biopsies,” which analyze tumor DNA circulating in the bloodstream, often referred to as circulating tumor DNA or ctDNA. 

The samples are then analyzed in a laboratory to look for specific genetic changes, proteins, or molecular features linked to cancer growth. Some tests examine a single biomarker, while others evaluate hundreds of genes at once. 

Biomarkers can help guide treatment decisions in many common cancers. Patients with non-small cell lung cancer, for example, may have their tumor tested for mutations in genes such as EGFR, ALK, KRAS, or BRAF to determine whether targeted therapies are an option. Breast cancers are commonly tested for hormone receptors and HER2 status, while colorectal cancers may be tested for KRAS, NRAS, and BRAF mutations.  

Researchers are also studying biomarkers that can help detect cancer earlier, monitor for recurrence, or predict cancer risk. PSA testing for prostate cancer and testing for the BCR-ABL gene in chronic myeloid leukemia are two examples already widely used in clinical care. Multi-cancer early detection (MCEDs) tests are another emerging area of research. These blood tests screen for many cancers at once – including those that don't have any recommended early-detection screenings. 

Biomarkers and the future of precision medicine 

While biomarker testing has transformed care for many patients, it is not yet helpful for every cancer type. Some cancers do not have known actionable biomarkers, and not all patients will benefit from targeted therapies. Access to testing can also vary depending on insurance coverage and the availability of specialized testing. Still, researchers say the field is advancing quickly. 

“There is tremendous momentum right now in discovering new biomarkers and developing therapies that target them,” says Wu. “We’re increasingly using molecular testing not only for risk stratification, but also to identify treatment options that simply did not exist a few years ago.” 

One rapidly growing area of biomarkers research at Columbia is in pancreatic cancer, where investigators such as Gulam Manji, MD, are studying emerging targets such as MTAP loss and PRMT5 inhibitors. Manji’s translational research seeks to understand why cancers eventually become resistant to targeted therapies. This work often involves analyzing tumor tissue and blood samples collected throughout treatment to track how cancers evolve over time. 

A multidisciplinary approach to biomarker-driven care 

At Columbia, biomarker testing and precision medicine are closely integrated into patient care. Physicians across specialties regularly review complex cancer cases together through multidisciplinary tumor boards, where medical oncologists, surgeons, radiation oncologists, pathologists, and researchers collaborate to discuss treatment options and emerging research that could benefit each patient. 

Biomarkers are helping us move away from a one-size-fits-all approach. The more we understand the biology of each person’s cancer, the more precisely we can treat it.

According to Wu, these discussions can help connect patients with promising clinical trials or new therapies that may not yet be widely available.  “We review a very high volume of cases, which gives us the opportunity to discuss new mutations, new research, and potential clinical trial options in real time,” she says. “It allows us to offer more precise and sometimes more creative approaches for patients.” 

In some cases, molecular testing may help identify unexpected treatment opportunities for patients whose cancers have stopped responding to standard therapies. “I recently had a patient whose cancer had progressed through several treatments and who did not want more chemotherapy,” says Wu. “Using input from our molecular tumor board, which includes experts from both pathology and molecular pathology, we developed a very unique combination of treatments that has helped stabilize the disease.” 

As researchers continue to discover new biomarkers and new targeted therapies, experts believe precision medicine will only become a larger part of cancer care in the years ahead. 

“Biomarkers are helping us move away from a one-size-fits-all approach,” says Wu. “The more we understand the biology of each person’s cancer, the more precisely we can treat it.”