NGS panel: what it is, what it looks for and how to request it

What is an NGS panel and how do I get one done?

Reviewed by: Equipo CRC Warriors (pendiente de revisión clínica) Last reviewed: 02/11/2026 Updated: 02/11/2026 4 min
In short: An NGS panel analyses dozens or hundreds of tumour genes at once to find alterations that have a treatment. In metastatic colorectal cancer guidelines recommend testing at least RAS, BRAF, MSI and HER2; a broad panel adds NTRK, PIK3CA, MET and others, useful mainly for clinical trials. If you have not had one, you can ask for it.

What NGS sequencing is

NGS stands for next-generation sequencing: a technique that reads the tumour's DNA (and sometimes RNA) across many genes at once. Genes used to be analysed one by one; now a single panel can cover anything from 20-50 genes ("targeted" panels) to more than 500 ("broad" or comprehensive panels). The aim is to find actionable alterations: changes that have an approved drug or a clinical trial.

What it should include in colorectal cancer

AlterationWhy it is useful to know
KRAS / NRASIf mutated, anti-EGFR drugs do not work. If it is KRAS G12C, there are specific drugs.
BRAF V600EEncorafenib + cetuximab; different prognosis.
MSI / MMRImmunotherapy; rule out Lynch syndrome.
HER2 (amplification)Anti-HER2 therapies; anti-EGFR drugs work less well.
NTRK (fusions)Very rare (<1 %), but with highly effective drugs (larotrectinib, entrectinib). More frequent in MSI-H RAS/BRAF wild-type tumours.
PIK3CA, MET, RET, ALK, ROS1No standard treatment in colon cancer, but they open the door to clinical trials.
TMB (tumour mutational burden)Guides immunotherapy in some cases; in colon cancer it carries less weight than MSI.
POLE / POLD1Rare; tumours with a huge number of mutations that respond to immunotherapy.

European guidelines (ESMO) consider testing RAS, BRAF and MSI mandatory in metastatic disease and recommend HER2; a broad NGS panel is recommended mainly when looking for clinical trials or once standard lines have been exhausted.

Tissue or blood

  • Tissue (biopsy or surgical specimen stored in paraffin): the standard. Material from years ago can be used, although the tumour may have changed since.
  • Blood (liquid biopsy): analyses the DNA the tumour sheds into the bloodstream. It is quick and non-invasive and reflects the current tumour, but it can give false negatives if the tumour releases little DNA. It is used when there is not enough tissue, or to check RAS before reusing an anti-EGFR.

Results normally take 2-4 weeks. If treatment cannot wait, it starts with what is already known and is adjusted afterwards.

How to request it

  1. First ask what has already been done. RAS, BRAF and MSI are often already in the pathology report, and what is missing is HER2 or the broad panel.
  2. Ask at your appointment, specifically: "Have I had an NGS panel? If not, can one be requested?" Most large hospitals run it in their own laboratory or send it to a regional reference centre; smaller hospitals refer the sample.
  3. If you are told it is not available: ask whether the sample can be sent to another public centre, whether there is a trial that includes molecular testing (trial screening does it free of charge), or whether a laboratory access programme exists. Phase I trial units usually run broad panels on the patients they assess.
  4. Privately: several laboratories offer broad panels on tissue or blood; the cost varies widely. If you go this way, ask for the report to be sent to your oncologist for interpretation and for the hospital to handle the sample.

How to read the report

  • Look for the section on actionable or "clinically relevant" alterations: these are the ones with a drug or a trial.
  • Many reports grade the evidence with the ESCAT scale (ESMO): tier I = approved treatment for your tumour; II-III = evidence from studies or from other tumours (trials); IV-V = no proven clinical use today.
  • "Variants of uncertain significance" (VUS) change nothing for now.
  • If a possible germline (inherited) alteration appears, you will be referred to genetic counselling.
  • The report usually lists clinical trials seeking your alterations; cross-check that list against those recruiting in Spain in our trial finder.

What to ask at your appointment

  • Which molecular alterations have already been tested in my tumour, and with what result?
  • Am I missing HER2 or a broad panel? Can it be requested here, or must the sample be referred?
  • Tissue or blood? How long will it take, and do we start treatment in the meantime?
  • Does any of my alterations have an approved drug or an open trial in Spain?
  • Is there anything in the report suggesting a hereditary alteration?

Frequently asked questions

Is an NGS panel covered by the public health system?

Yes, when your oncologist requests it with a clinical indication; RAS, BRAF, MSI and increasingly HER2 are routine. The broad panel depends on the hospital and the region: some run it routinely in metastatic disease and others only in specific situations. If it is not available, ask about referral or trials.

Do I need a new biopsy?

Usually not: the paraffin block from the surgery or original biopsy is used, which the hospital keeps for years. A new biopsy is only considered if the material is insufficient or very old, or a blood liquid biopsy is chosen instead.

What if the panel finds nothing "actionable"?

That is the most common outcome in colon cancer: most tumours have nothing beyond RAS or BRAF, which were already known. It does not mean there is no treatment; it means the options are the standard ones (chemotherapy, anti-angiogenic drugs) and trials that do not require a specific mutation.

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Sources

This guide is general information prepared by the CRC Warriors Association (non-profit) from public medical sources. It does not replace the assessment of your oncologist or medical team, who know your case. If you spot an error, write to contacto@crcwarriors.org.