Monitoring cancer with repeat biomarker testing

How repeat biomarker testing is done

Just like biomarker tests that happen after diagnosis, repeat biomarker testing can be performed in two ways:

• Tissue biopsy: This involves removing a small sample of tissue from an individual tumor for analysis. It provides detailed information about the cancer’s genetic and molecular profile. Although it does require a procedure with local anesthesia and a recovery period, tissue biopsies are the gold standard and can provide a great amount of information about your cancer.
• Liquid biopsy: This is a test that looks at blood or another body fluid, such as saliva or urine, for fragments of tumor DNA or other biomarkers circulating in the bloodstream. Liquid biopsies are less invasive, can be repeated more frequently than tissue biopsies, and can provide quicker results. They are especially useful for monitoring changes over time and can be used to capture information if there are multiple tumor sites. However, they aren’t considered the gold standard, as they are generally less sensitive than tissue biopsies and may not provide the same level of detail.

These two types of biopsies give doctors a clearer picture of how your cancer is evolving and if there is a need to take a different approach or begin you on a new targeted therapy.

Repeat biomarker testing is designed to provide critical insights. Whether through a blood draw, liquid collection, or tissue sample, these tests help ensure your treatment plan can be adapted to address any changes that may occur.

Benefits of repeat biomarker testing

Repeat biomarker testing doesn’t always lead to a change in treatment, and all biomarkers aren’t directly tied to specific therapies. Even so, checking them over time can reveal important shifts in how your cancer is behaving, and when meaningful changes do appear, they can support the following aspects of your care:

• Tracking treatment effectiveness: By understanding how your cancer is responding, doctors can make appropriate adjustments, whether that means continuing your current therapy, changing the dose, or switching to a new treatment.
• Identifying treatment resistance: Cancer can develop resistance to certain drugs over time. Repeat testing helps identify these changes early, so your care team can act in a timely manner.
• Accessing clinical trials: Many clinical trials require specific biomarkers for eligibility. Updated testing can help open the door to more opportunities for potential new therapies.
• Detecting recurrence: Even after successful treatment, some cancers can return. Repeat biomarker testing can help spot signs of recurrence even before they appear on scans or cause symptoms. For example, a rise in certain biomarkers may be one of the first clues that cancer cells are active again, giving your doctor the opportunity to intervene sooner.
• Informing precision care: Biomarker trends allow your doctor to tailor treatment to your cancer’s unique characteristics, rather than relying on a one-size-fits-all approach.

Interpreting results and next steps

Biomarker trends tell a story about how your cancer is behaving and responding to treatment. Here’s what those changes can mean:

• Stable or decreasing levels: This may suggest your treatment is working as intended. Your doctor may recommend continuing the current therapy.
• Rising levels: This can indicate that the cancer is becoming resistant to treatment or that it has returned. Detecting this early allows your care team to act quickly.
• New biomarkers detected: Sometimes, repeat testing reveals new genetic changes. These may open the door to different targeted therapies or clinical trials.

Your doctor will review the results and discuss options such as:

• Adjusting your current treatment
• Switching to a new therapy that targets the updated biomarkers
• Considering clinical trial enrollment

Biomarker results can be complex. Always ask your care team to explain what the results mean for your specific situation. This discussion guide will help you prepare questions to ask your doctor. Understanding the next steps can help you feel more informed about your treatment plan.