Testing Resources
Comprehensive Breast Cancer Testing Options

Cancer Testing Options Table

Comprehensive testing information with sortable columns, search functionality, and detailed comparisons

TIER 1: STANDARD OF CARE - AUTOMATIC TESTING
TIER 2: GUIDELINE-RECOMMENDED TESTING
TIER 3: FDA-APPROVED COMPANION DIAGNOSTICS
TIER 4: RESEARCH-VALIDATED BIOMARKER TESTING
TIER 5: COMPREHENSIVE GENOMIC/EXPRESSION TESTING
TIER 6: FUNCTIONAL TESTING
TIER 7: COMMERCIAL/QUESTIONABLE VALIDITY
GENERAL HEALTH TESTING

Important Notes

SIGNATERA SPECIAL NOTE: Signatera performs full whole exome sequencing on BOTH tumor tissue AND germline (normal) DNA to design their personalized 16-variant panel. While they only report on 16 variants for monitoring, patients can request access to their complete exome sequencing data from BOTH tumor AND germline samples.

TEMPUS SPECIAL NOTES:

Tempus xF+ Clonal Evolution Analysis: The 523-gene liquid biopsy panel enables tracking of tumor genetic changes over time, providing insights into clonal evolution and resistance mechanisms.

Tempus xR Transcriptome Analysis: Provides whole transcriptome sequencing (23,000+ genes) enabling extensive secondary analysis including custom gene signatures and pathway analysis.

CEtHI DATA OWNERSHIP PRINCIPLE: Full exome + transcriptome data can subsume many targeted tests through secondary analysis. Tests marked with "Secondary Analysis" badges collect more comprehensive data than they report and/or are amenable to more comprehensive analyses.

Understanding Cancer Testing Data Types

Understanding Cancer Testing Data Types

A Guide to Genomic, Expression, and Functional Analyses

Genomic Data: The Foundation of Molecular Testing

Normal (Germline) vs. Tumor Tissue Genomic Data

Genomic data examines DNA sequences, but the source matters enormously. Germline genomic data comes from normal tissue (blood, saliva) and represents your inherited genetic blueprint - the DNA you were born with. When we test for BRCA1/BRCA2 mutations in blood, we're looking for inherited predispositions passed down through families.

Tumor genomic data, by contrast, examines DNA from cancer cells themselves. These contain both your original inherited DNA plus additional somatic mutations - genetic changes that occurred during cancer development. A person might have normal germline BRCA1/BRCA2 genes but develop somatic BRCA mutations specifically in their tumor tissue.

Example: Foundation One CDx sequences 324 genes from tumor tissue to find somatic mutations that can guide targeted therapies, while hereditary cancer panels sequence the same genes from blood to find inherited risk variants.

Expression Data: From Proteins to Transcriptomes

Expression data measures what genes are actually doing rather than just what the DNA sequence says. This represents the dynamic, functional output of the genome.

Standard Expression Markers (ER/PR/HER2)

These classic biomarkers use immunohistochemistry (IHC) to measure specific proteins directly in tissue. When we say a tumor is "ER+" we mean estrogen receptor proteins are detectable on cancer cell surfaces. This is targeted, focused expression analysis of known important proteins.

Whole Transcriptome Expression

RNA sequencing measures the expression levels of all ~23,000 human genes simultaneously by quantifying messenger RNA (mRNA) molecules. This provides a comprehensive snapshot of cellular activity - which genes are turned "on" or "off" and by how much.

Example: Oncotype DX measures RNA expression of 21 specific genes to calculate a recurrence score. Tempus xR performs whole transcriptome sequencing of all genes. This comprehensive dataset can then yield the same 21-gene signature plus thousands of other potential biomarkers.

Immune Profiling Through Expression Data

Immune profiling typically uses RNA sequencing to measure expression of immune-related genes. Tests like NanoString IO360 examine 770 immune genes to characterize the tumor microenvironment - are T-cells infiltrating? Are immune checkpoint pathways active? This helps predict immunotherapy response by understanding the immune landscape around the tumor.

Circulating Tumor DNA (ctDNA): The Liquid Biopsy Revolution

ctDNA represents fragments of tumor DNA that circulate freely in blood. When cancer cells die, they release their DNA into the bloodstream. Advanced sequencing can detect these tumor-derived DNA fragments among the much larger background of normal cell-free DNA.

Key Advantages

  • Non-invasive: Simple blood draw vs. tissue biopsy
  • Real-time monitoring: Can track changes during treatment
  • Comprehensive sampling: Captures DNA from all tumor sites, not just one biopsy location
Example: Guardant360 CDx analyzes 74 genes from blood ctDNA to guide treatment decisions, while Signatera creates a personalized panel of 16 tumor-specific mutations to monitor for minimal residual disease after treatment.

Functional Testing: Beyond Genetics to Actual Behavior

Functional testing moves beyond "what mutations does the tumor have?" to "how does the tumor actually behave?" This involves growing tumor cells in laboratory conditions and directly testing their response to various treatments.

Methods

  • Organoids: 3D tissue cultures that mimic tumor structure
  • Drug screening: Testing multiple chemotherapy agents directly on patient cells
  • Sensitivity profiling: Measuring which drugs kill tumor cells most effectively
Example: Champions TumorGraft3D grows patient tumor cells in 3D culture and tests their response to dozens of drugs, providing direct functional evidence of drug sensitivity rather than inferring it from genetic mutations.

SNP Data: Population Genetics and Common Variants

Single Nucleotide Polymorphisms (SNPs) represent common genetic variants found throughout human populations. Unlike rare disease-causing mutations, SNPs are normal genetic differences that occur in >1% of people.

SNP Arrays

Test ~700,000 predetermined positions

Assess common variants linked to traits/diseases

Broad but shallow coverage

Clinical Sequencing

Read entire gene sequences

Find rare pathogenic mutations

Deep and comprehensive

Example: 23andMe tests SNPs associated with BRCA1/BRCA2 regions but only captures ~0.1% of possible pathogenic variants, while clinical BRCA sequencing reads every DNA letter in these genes to find rare disease-causing mutations.

Emerging and Advanced Data Types

Epigenetic Data: The Genome's Control Layer

Epigenetic modifications control gene expression without changing DNA sequence itself. DNA methylation patterns can silence tumor suppressor genes even when the underlying DNA is normal. Methylation-based tests like Galleri detect cancer by identifying abnormal methylation patterns across thousands of genes.

Proteomic Data: The Functional Output

While genomics tells us what could happen and transcriptomics what should happen, proteomics measures what actually is happening. Mass spectrometry can quantify thousands of proteins simultaneously, revealing post-translational modifications and protein interactions that don't show up in DNA or RNA data.

Metabolomic Data: Cellular Chemistry in Action

Metabolomics measures small molecules (metabolites) that represent the end products of cellular processes. Cancer cells often have altered metabolism, producing unique metabolic signatures detectable in blood or urine.

Cutting-Edge Multimodal AI Analysis

Genomics + Imaging Integration

Emerging AI approaches combine multiple data types for more powerful analysis. Radiogenomics uses machine learning to predict genetic mutations directly from medical images (CT, MRI, pathology slides). For example, AI can predict EGFR mutations in lung cancer from CT scans, or identify microsatellite instability from H&E pathology slides without additional molecular testing.

Multimodal Pathology AI

Advanced systems analyze digitized pathology slides alongside genomic data to predict treatment responses, identify missed diagnoses, or discover new biomarkers. The AI learns patterns invisible to human pathologists by processing millions of image features simultaneously.

CEtHI Secondary Analysis Opportunity

Since medical images (pathology slides, radiology) are typically provided to patients as part of their medical records, organizations like CEtHI with appropriate AI/imaging expertise could potentially perform secondary analyses combining imaging data with genomic results - extracting additional insights from data patients already own without requiring new tests.

Secondary Analysis: Making Comprehensive Data Work Harder

The Power of Comprehensive Data Collection

When a test performs whole exome sequencing (20,000+ genes) but only reports results for a specific gene panel, the unreported data doesn't disappear - it remains available for future analysis. This enables "secondary analysis" where comprehensive datasets can answer new questions without additional testing.

Examples

  • Signatera: Performs whole exome sequencing on tumor and normal tissue but initially reports only 16 personalized variants for monitoring. Patients can later request analysis of cancer predisposition genes, pharmacogenomic variants, or other findings from the same dataset.
  • Tempus xR: Sequences the entire transcriptome but initially focuses on clinically actionable findings. The same data can later be reanalyzed for research signatures, pathway analysis, or newly discovered biomarkers.

Why This Matters

Secondary analysis democratizes access to comprehensive testing by allowing targeted test results to be extracted from broad datasets, often at lower cost than running separate tests.

Current Limitations and the Research-to-Clinical Gap

Insurance and Standard of Care Barriers

Advanced multimodal analyses and many secondary analyses are not covered by insurance because they are not yet considered "standard of care." Insurance systems typically lag years behind scientific developments, requiring extensive clinical trial validation before coverage approval.

The Clinical Translation Lag

A significant gap exists between research developments and clinical application. Promising biomarkers and AI-based analyses may show strong research evidence but require 5-15 years to become clinically adopted. During this period, patients may benefit from research-grade information that their healthcare systems cannot yet provide.

Access Limitations

Most cutting-edge analyses remain confined to academic medical centers or research institutions. Standard community oncology practices may lack access to the latest developments, creating disparities in available information. Organizations like CEtHI aim to bridge this gap by providing research-grade analyses directly to patients, empowering informed decision-making without waiting for traditional clinical adoption timelines.

One key CEtHI objective is to bridge the gap between
what we know in research and
what we do in the clinic.

As a genetic epidemiologist, I am in position to help patients navigate the full spectrum
of testing options and leverage comprehensive molecular data for informed decision-making.


Patient Empowerment. Patient Dignity. Patient Flourishing.
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