Biomarker Conversation Guide

Understanding Your Biomarker Results

What are biomarkers? 

Biomarkers are clues in your cancer cells or blood. They can help your care team choose treatments, avoid medicines that may or may not work well, or watch for signs that cancer may come back.

Bring to your visit: 

  1. Your biomarker report 
  2. This guide 
  3. A person you trust or a place to take notes

Get Your Free Biomarker Brochure

Our Biomarkers brochure outlines information your biomarker report should contain, why biomarkers are so important to know for treatment options, and why biomarker testing is so important.

My Test Results at a Glance 

At diagnosis

    • DNA repair (MMR/MSI): ☐ Tested / ☐ Not yet
      ☐ MSI-H (dMMR) ☐ MSS (pMMR) ☐ Unsure

    • Tumor side: ☐ Left ☐ Right     ☐ Unsure
    • Rectal tumors are often grouped with left-sided tumors for some treatment discussions. Ask your care team how tumor location applies to you.

Before certain chemotherapy medicines

    • DPYD (before 5-FU/capecitabine): ☐ Tested / ☐ Not yet
      ☐ Normal function ☐ Reduced function ☐ No Function    ☐ Unsure

    • This test can help your care team choose a safer starting dose and monitoring plan

    • UGT1A1 (before irinotecan in some cases): ☐ Tested / ☐ Not yet
      ☐ Typical-risk ☐ Higher-risk ☐ Unsure

    • This test may help your care team understand side-effect risk and decide whether dose changes or extra monitoring are needed

If you have stage IV (metastatic), before your first treatment

    • KRAS: ☐ Tested / ☐ Not yet  ☐ Wild-type ☐ Positive ☐ Unsure

    • KRAS G12C: ☐ Detected ☐ Not detected ☐ Unsure

    • NRAS: ☐ Wild-type ☐ Positive ☐ Unsure

    • BRAF: ☐ Wild-type ☐ V600E ☐ Other: ☐ Unsure

    • HER2 (ERBB2): ☐ Positive ☐ Negative ☐ Unsure

    • NTRK fusion: ☐ Detected ☐ Not detected ☐ Unsure

    • KRAS G12C is one specific KRAS change that may open certain treatment options later.

Other results my report may include

POLE/POLD1, PIK3CA, RET, ALK, HER2 mutation, and others. Ask which results matter for your care.

Other: ____________

Plain words first, medical words second: NGS = broad tumor profiling. ctDNA or MRD = tumor DNA in blood. CEA = blood tumor marker.

Timing at a Glance

When Why this matters  How long it may take Sample
At diagnosis  MMR or MSI can help guide treatment and genetic counseling conversations. Often within days to about 2 weeks Tumor tissue
Before certain chemotherapy medicines DPYD and sometimes UGT1A1 can help personalize dosing and monitoring About 3 to 10 business days, sometimes longer Blood draw or saliva or cheek swab
If metastatic, before first treatment NGS helps identify targets before choosing first-line therapy. Tissue NGS about 2 to 3 weeks. Liquid biopsy often about 5 to 10 business days Tumor tissue and or blood
After surgery or if cancer changes CtDNA can help guide follow-up and trial conversations, but it does not replace scans, exams, CEA testing, or your care team’s judgement Varies by test Usually blood, sometimes tissue for setup

***Times vary by lab, insurance steps, and sample quality. Ask your clinic when to expect results and whether they will appear in your patient portal.

Need quick answers? ChatCRC is in your corner.

Text ChatCRC today (318) 242-8272

Questions That Put You in Control

Only have time for 3 questions? Start here: 

  1. What biomarker results do I have right now? 
  1. Are any results missing before we choose treatment? 
  1. How do these results change my next step? 

 

If you were just diagnosed 

  • What is my MMR/MSI result? 
  • Could this affect my treatment? 
  • Do I need genetic counseling for possible Lynch syndrome? 
  • Can I get a printed copy of my results? 

Before certain chemotherapy medicines 

  • Did we check DPYD and, if needed, UGT1A1 before treatment starts? 
  • How will these results affect my starting dose or monitoring plan? 
  • What side effects should I watch for in the first 1 to 2 weeks? 
  • Who should I call if I have symptoms? 

If you have stage IV (metastatic) disease 

  • Do we have my NGS results before choosing first treatment? 
  • Does my report include KRAS, NRAS, BRAF, HER2, KRAS G12C, and NTRK? 
  • What are my top treatment options and why? 
  • If I am RAS wild-type and left sided, should we discuss whether an anti-EGFR approach fits my care? 

After surgery 

  • Should we do a ctDNA, also called MRD testing, now? 
  • If positive or negative, how would that affect follow-up or trial options? 
  • How often would we repeat ctDNA? 
  • Was my tumor tested for PIK3CA or another PI3K pathway change, and should we talk about whether aspirin is safe and appropriate for me? 

ctDNA can help guide follow-up and trial conversations, but it should not be used by itself to make treatment decisions. 

During follow-up 

  • What is my CEA trend? 
  • When is my next scan? 
  • If CEA rises, when would we move the scan sooner? 
  • What symptoms should prompt me to call early? 

If cancer changes or returns 

  • Should we re-test now to look for new options? 
  • Would a liquid biopsy be faster while planning a tissue biopsy? 
  • What new targets or clinical trials are we hoping to find? 

Insurance Help 

  • Ask your care team for prior authorization and a letter of medical necessity. 
  • If coverage is denied, ask for the denial in writing and appeal quickly. 
  • Ask the lab or testing company about financial assistance or capped cash-pay programs. 
  • Ask your financial counselor or navigator for help with codes, deadlines, and appeals. 

Take Control of Your Health 

  • Keep asking until you understand. 
  • Bring someone with you or take notes. 
  • Leave with a next step: what’s happening, when, and how we’ll follow up. 

This resource is for education and conversation support. It does not replace medical advice. Use it with your care team to make decisions that are right for you. 

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