My father has colon cancer. How does genomic testing guide treatment?

Question

Hello doctor,

My father, 62, was recently diagnosed with stage III colon cancer, and his oncologist suggested genomic profiling to guide treatment. I do not quite understand what that means.

How is this different from regular biopsy or pathology reports?
They mentioned checking for KRAS, NRAS, and MSI status. What do those tell, and how do they influence treatment decisions?
Does this testing also give information about inherited cancer risks for family members like me?
How accurate and reliable are these results, and should we consult a specialized center for this?
Is it expensive, or is it usually covered by insurance?

Kindly suggest.

Answer 1

Hello,

Welcome to icliniq.com.

I understand your concern.

So, genomic profiling in colon cancer goes beyond the standard biopsy and pathology, which mainly confirm the cancer type, stage, and microscopic appearance.

Instead, it looks at the tumor’s DNA (deoxyribonucleic acid) for specific genetic changes that influence how the cancer behaves and responds to treatment.

For example, KRAS (Kirsten rat sarcoma viral oncogene homolog) and NRAS (neuroblastoma RAS viral (v-ras) oncogene homolog) mutations tell doctors whether drugs called EGFR (estimated glomerular filtration rate) inhibitors (like Cetuximab) will work if these mutations are present; those drugs are not effective.

MSI (microsatellite instability) status shows whether the tumor has a defect in DNA repair; MSI-high cancers often respond very well to immunotherapy and carry implications for Lynch syndrome, an inherited condition that increases colon and other cancer risks in families.

While tumor genomic profiling is focused on the cancer cells themselves, if something suspicious for an inherited mutation is found, your father may be referred for separate germline genetic testing to clarify whether it runs in the family.

These tests are generally very accurate and widely used in oncology, and many large hospitals and cancer centers can perform them, though sometimes samples are sent to specialized laboratories.

Costs can vary, but in many countries and insurance systems, key tests like KRAS or NRAS and MSI are considered standard of care and are usually covered.

I hope this helps. Always feel free to reach out at any time. I am always here to help.

Thank you.