A genomic profiling report is not simply a list of mutations. It is a biological snapshot of a tumor at a specific moment in its evolution.
The first page of an NGS report often highlights selected findings and potential treatment options. But meaningful interpretation requires looking beyond the summary. The clinical significance of any finding depends on its biological context, technical reliability, level of evidence, and relevance to the specific tumor type and stage of disease.
The major components of an NGS report
A comprehensive genomic profiling (CGP) report layers several kinds of information. Reading it well means knowing what each layer can, and cannot, tell you.
Genomic alterations
The variant list forms the foundation of the report, but individual alterations should never be interpreted in isolation.
Variant Allele Frequency VAF
VAF represents the proportion of sequencing reads containing a specific alteration. In clinical practice, it may help answer important questions:
- Is the alteration likely clonal or subclonal?
- Could it represent a major tumor driver or an emerging resistant clone?
- Is the finding biologically relevant enough to influence treatment decisions?
Tumor purity
Tumor purity refers to the proportion of tumor cells present within the analyzed specimen. Low tumor content may reduce the sensitivity of testing and can result in clinically relevant alterations being missed. Consequently, a negative result does not always mean the absence of a genomic alteration.
Learn more · Tumor purity and its impactGermline vs somatic alterations
Some alterations arise only within tumor cells (somatic), while others may be inherited and present in every cell of the body (germline). Distinguishing the two matters not only for treatment planning but also for hereditary cancer risk assessment and family counseling.
Learn more · Germline vs somatic variantsVariant classification
Not all genomic findings carry the same level of certainty. Variants are commonly classified as:
- Pathogenic
- Likely Pathogenic
- Variant of Uncertain Significance (VUS)
Understanding these categories is essential, as most VUS findings should not independently drive treatment decisions.
Learn more · Pathogenic, Likely Pathogenic & VUSBiomarkers beyond individual mutations
Modern genomic reports frequently include broader biomarkers that provide additional biological and therapeutic information.
Tumor Mutational Burden TMB
TMB estimates the number of mutations present within the tumor genome and may have implications for immunotherapy in selected settings.
Learn more · Understanding TMBMicrosatellite Instability & Mismatch Repair Deficiency MSI · dMMR
These biomarkers reflect defects in DNA repair mechanisms and may predict sensitivity to immune checkpoint inhibitors across multiple tumor types.
Learn more · Understanding MSI / dMMRHomologous Recombination Deficiency HRD
HRD reflects impairment of specific DNA repair pathways and may influence the use of PARP inhibitors in selected cancers.
Learn more · Understanding HRDLoss of Heterozygosity LOH
LOH measures genomic loss events and may contribute to the assessment of homologous recombination deficiency.
Learn more · Understanding LOHTranslating genomic findings into clinical decisions
The most important question is rarely:
“What mutation was found?”
The more relevant question is:
“Does this finding change clinical management?”
Clinical interpretation requires consideration of:
- Therapeutic relevance
- Tumor-specific evidence
- Strength of supporting data
- Available targeted therapies
- Potential clinical trial opportunities
- Known resistance mechanisms
A biomarker that is actionable in one tumor type may not necessarily be actionable in another.
How we read an NGS report
At NGS Advisory, every case is evaluated using a structured framework: six questions, asked in order, before any conclusion is drawn.
Is the finding technically reliable?
Before discussing biological significance, we assess sequencing quality, coverage, tumor purity, and the technical limitations of the assay.
Is the alteration biologically important?
We distinguish between:
- Driver alterations
- Passenger alterations
- Resistance mechanisms
- Potential clonal hematopoiesis (CHIP)
- Variants of uncertain significance
Is the finding clinically relevant in this tumor type?
An alteration may be targetable in one cancer and clinically irrelevant in another. Tumor context matters.
What is the level of evidence?
We evaluate findings according to established evidence frameworks, including:
- AMP / ASCO / CAP classification
- ESCAT classification
- Regulatory approvals
- Prospective clinical trial data
Not all actionable findings carry the same level of confidence.
Where is the patient in the disease course?
The same biomarker may have very different implications depending on line of therapy, prior treatments, acquired resistance, and disease evolution.
What is the strategy beyond the next treatment?
Precision oncology is not only about selecting a therapy. It is also about anticipating resistance mechanisms, sequencing future options, and identifying opportunities that may become relevant later in the patient’s journey.
Why a second review can matter
Two experienced clinicians may reach different conclusions from the same genomic report. This is not necessarily a flaw in the data; it reflects the complexity of interpreting genomic information under clinical uncertainty.
Meaningful interpretation requires integrating:
- Molecular pathology
- Tumor biology
- Genomic context
- Clinical evidence
- Therapeutic strategy
A structured expert review makes the reasoning process transparent, allowing conclusions to be critically evaluated rather than simply accepted.
Precision oncology begins with interpretation
Genomic testing generates data. Clinical value emerges only when that data is translated into a biologically and clinically coherent strategy.
Understanding how to read an NGS report is the first step in that process.
This content is intended for educational purposes only. It does not constitute individual medical advice and should not replace evaluation by the treating physician.