The short answer
An NTRK fusion is a biomarker result. It means a gene fusion involving an NTRK gene. In some cancers, biomarker results can help guide targeted therapy, immunotherapy, or clinical trial options, but the result only matters in context.
An NTRK fusion is a biomarker or molecular result, not a treatment decision by itself.
It can be relevant in rare subsets of many solid tumors.
A positive result may or may not change treatment depending on cancer type, stage, prior treatment, and available options.
Ask whether the result is from tumor testing, blood testing, inherited genetic testing, or another method.
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The full explanation.
The short answer
An NTRK fusion means part of an NTRK gene has broken off and joined a different gene, creating a fused gene that makes an overactive growth protein. These fusions are rare, but they can occur in many different cancers, in adults and in children. When one is present, it is usually the main thing driving the cancer.
Where it may be relevant
This result can be relevant in rare subsets of many solid tumors, although not every person with those cancers needs or benefits from the same testing or treatment.
Why it can affect treatment options
NTRK fusions are one of the clearest examples of treatment chosen by the biomarker rather than by where the cancer started. Larotrectinib, entrectinib, and repotrectinib are TRK inhibitor pills approved for advanced solid tumors with an NTRK fusion when there is no good alternative treatment. Responses are often strong and can last a long time, though cancers can eventually develop resistance, and repotrectinib was designed partly with that in mind. These approvals came through the FDA's accelerated pathway, so longer-term data are still being collected. This result points toward targeted therapy, not immunotherapy. Ask whether the fusion was confirmed and which drug fits.
Report language patients may see
The report may say positive, detected, not detected, expression, mutation, fusion, rearrangement, score, variant, or insufficient tissue. Ask which word applies to NTRK fusion and whether the lab result is complete.
Questions to ask
Ask whether the result is actionable, whether it changes the next treatment choice, whether more testing is needed, and whether a matched clinical trial is worth discussing.
Words to know
Tap any term to see what it means.
Common questions
What is an NTRK fusion?
An NTRK fusion means a gene fusion involving an NTRK gene. It is one type of result that may appear on a biomarker, molecular, genomic, or pathology report.
Can it affect treatment?
Sometimes. Certain biomarkers can point toward targeted therapy, immunotherapy, or a clinical trial, but the same result can mean different things in different cancers.
What should I ask my oncologist?
Ask whether the result is actionable for your cancer, whether a matched treatment exists, and whether a trial is relevant.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
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Your next step
Look up more plain-language explanations for report wording.
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