Introduction
In our previous blog post, we explored some of the early breakthroughs that reshaped cancer treatment. Precision oncology is an approach to cancer treatment that is tailored to the unique biology of a patient’s tumor. This raises an important question: what makes precision oncology possible? The answer lies in biological markers, more commonly known as biomarkers.
What Is a Biomarker?
A biomarker is a measurable biological signal that provides insight into what is happening inside the body. It can reflect normal biological processes, the presence of disease, or how the body is responding to treatment.
Biomarkers can take many forms, including genes, proteins, or imaging findings. In cancer, specific genetic changes within a tumor can act as biomarkers, helping doctors understand how the cancer may behave and how it may respond to treatment.
For example, certain mutations in cancer cells can indicate whether a tumor is more aggressive or if a patient may benefit from a targeted therapy. These insights enable more informed, personalized treatment decisions.
Why Biomarkers Matter in Cancer Care
In cancer care, biomarkers are measurable features, such as genes or proteins, that provide insight into how cancer behaves. These biomarkers support more accurate diagnosis, guide treatment selection, help avoid overtreatment, and monitor disease progression. In some cases, advanced biomarker tests can guide treatment decisions even before surgery.
Biomarkers can be grouped into several categories, including risk, diagnostic, monitoring, prognostic, and predictive biomarkers. In oncology, they are most commonly used to assess risk, diagnose disease, predict outcomes, guide treatment decisions, and monitor disease over time.
A susceptibility or risk biomarker indicates the likelihood that an individual may develop a disease or medical condition. One well-known example is mutations in breast cancer genes 1 and 2 (BRCA1 and BRCA2), which can identify individuals with a higher predisposition to developing breast cancer. BRCA1 and BRCA2 are tumor suppressor genes that help repair damaged DNA. Mutations in these genes prevent proper DNA repair, which increases the risk of developing cancers, including breast and ovarian cancer.
Diagnostic biomarkers help detect the presence of a disease or condition. For instance, Alpha-fetoprotein (AFP) is a blood biomarker used to help diagnose and monitor liver cancer. AFP levels often correlate with tumor size and aggressiveness. Another example is Prostate-Specific Antigen (PSA), a blood-based protein produced by prostate cells that is commonly used for early prostate cancer screening.
Monitoring biomarkers are measured over time to assess disease status or progression. A common example is Cancer Antigen 125 (CA-125), a blood biomarker used to monitor epithelial ovarian cancer. Changes in CA-125 levels can help clinicians evaluate treatment response and detect potential recurrence. In some cases, rising CA-125 levels may signal cancer recurrence months before symptoms appear.
A prognostic biomarker provides insight into the likely course of a disease, including the risk of recurrence or progression. One example is the Oncotype DX Breast Recurrence Score Test, a genomic test that analyzes the expression of 21 tumor genes to estimate the risk of breast cancer recurrence and determine whether chemotherapy is likely to provide benefit.
A predictive biomarker identifies individuals who are more likely to respond to a particular therapy. A well-known example is Human Epidermal Growth Factor Receptor 2 (HER2), which serves as a predictive biomarker for trastuzumab therapy. Tumors with high HER2 protein expression are considered HER2-positive and identify patients who are more likely to benefit from trastuzumab, a targeted therapy that blocks the HER2 receptor and inhibits tumor growth.
Conclusion
Biomarkers allow physicians to move beyond a one-size-fits-all model of cancer treatment and toward more personalized care tailored to each patient’s tumor biology. As precision oncology continues to evolve, new biomarkers are being discovered and validated, helping clinicians better understand cancer and make more informed, personalized treatment decisions.
As the number of clinically relevant biomarkers continues to grow, so does the need for reliable diagnostic technologies capable of detecting them. In our next article, we will explore the key laboratory technologies used to identify cancer biomarkers and how they are transforming precision oncology.