Tumor Genomic Profiling and Multigene Panels

Tumor genomic profiling is the laboratory analysis of a cancer's DNA to identify the somatic alterations it carries, most often using multigene panels - assays that interrogate tens to hundreds of cancer-relevant genes in a single run by massively parallel sequencing. These panels sit between testing one gene at a time and sequencing the whole genome, offering broad coverage of clinically and biologically important genes from limited tumor material.

Definition

A multigene panel is a targeted next-generation sequencing assay that simultaneously examines a defined set of cancer-associated genes for somatic alterations - including point mutations, small insertions and deletions, copy-number changes, and selected rearrangements - in tumor-derived nucleic acid.

Scope

This entry covers what genomic profiling panels are, the classes of alteration they detect, how they differ from single-gene assays and whole-genome or whole-exome sequencing, and how detected variants are interpreted and reported. It is a methodological reference within tumor molecular profiling and does not prescribe which test to order or how to act on a result.

Core questions

• Which classes of somatic alteration can a given panel reliably detect?
• How do targeted panels compare with whole-exome and whole-genome sequencing in coverage and depth?
• How are detected variants filtered, interpreted, and reported in clinically meaningful tiers?
• What analytic factors - depth, limit of detection, specimen quality - govern a panel's validity?

Key concepts

• Targeted next-generation sequencing
• Massively parallel sequencing
• Sequencing depth and coverage
• Limit of detection and variant allele fraction
• Comprehensive genomic profiling
• Whole-exome and whole-genome sequencing
• Tiered variant interpretation
• Analytic validation

Mechanisms

Tumor nucleic acid is extracted, enriched for the target genes by hybrid capture or amplicon methods, and sequenced to high depth so that variants present in only a fraction of the cells can be detected against background. Bioinformatic pipelines align reads, call point mutations, small insertions and deletions, copy-number changes, and selected structural rearrangements, and filter out germline and technical artefacts. Panels concentrate sequencing on cancer-relevant genes, which allows greater depth and sensitivity for low-frequency variants than genome-wide approaches at comparable cost, while whole-exome and whole-genome sequencing trade depth for breadth. Curated knowledge bases and standardized criteria are then applied to classify each variant by its clinical and biological significance.

Clinical relevance

Genomic profiling panels are the workhorse assays of molecular oncologic pathology and the practical means by which tumors are characterized at scale. As a reference topic this entry explains how such testing works and how its outputs are structured and validated; it describes laboratory methodology and evidence and is not a basis for selecting tests or therapies for an individual.

Epidemiology

Profiling of very large tumor series with broad panels has quantified how often particular alterations occur across cancer types and has supported genome-derived metrics such as tumor mutational burden, demonstrating that panel data aggregated across many patients can describe the broader landscape of somatic alteration in human cancer.

History

Molecular testing of tumors began with single-gene and hotspot assays, but the arrival of massively parallel sequencing made it feasible to interrogate many genes at once from routine, often small, specimens. Validated clinical genomic profiling tests were developed and described in the early 2010s, and professional societies subsequently published standards for interpreting and reporting the somatic variants these assays produce, establishing panel-based profiling as a defined diagnostic practice.

Debates

Targeted panels versus whole-genome or whole-exome sequencing

Targeted panels offer high depth and sensitivity for known cancer genes at lower cost, while broader sequencing captures alterations outside predefined gene sets and supports genome-wide metrics; the appropriate breadth depends on the purpose of testing and remains an active methodological discussion.

Seminal works

• frampton-2013
• li-2017

Frequently asked questions

What is the difference between a multigene panel and whole-genome sequencing?

A multigene panel sequences a defined set of cancer-relevant genes to high depth, which improves sensitivity for low-frequency variants and lowers cost, whereas whole-genome sequencing reads the entire genome at lower depth, capturing alterations anywhere but with less sensitivity for rare subclonal variants.

What kinds of alterations can a genomic profiling panel detect?

Depending on its design, a panel can detect point mutations, small insertions and deletions, copy-number changes, and selected gene fusions or rearrangements, and can support derived measures such as tumor mutational burden.