PRECISION ONCOLOGY AND
BIOMARKER TESTING
A complete patient guide to precision oncology โ what biomarker testing involves, which tests matter for which cancers, and how ensuring a complete molecular profile at the right time can fundamentally change your treatment options.
analyticsAt a Glance
- check_circleBiomarker testing identifies the specific molecular drivers of your cancer โ unlocking targeted treatments not available to unselected patients
- check_circleMissing a biomarker at diagnosis can mean missing the most effective treatment entirely
- check_circleNext-generation sequencing (NGS) now allows comprehensive profiling of hundreds of cancer genes from a single biopsy
- check_circleCancerFax reviews your biomarker panel for completeness and advises on additional testing where gaps exist
What Is Precision Oncology?
Precision oncology is the practice of matching cancer treatment to the specific molecular characteristics of a patient's tumour โ rather than treating all cancers of the same organ type with the same standard regimen. It requires biomarker testing: laboratory analysis of tumour tissue (or blood) to identify the genetic mutations, protein expressions, and immune characteristics that drive that specific cancer.
โTwo patients with the same stage of the same cancer may have completely different molecular drivers โ and completely different optimal treatments. Biomarker testing reveals which patient you are.โ
Biomarker
A biological molecule โ a protein, gene mutation, gene expression pattern, or immune cell marker โ that can be measured in tumour tissue or blood and used to predict response to a specific treatment. HER2, PD-L1, KRAS, BRAF, MSI, and CLDN18.2 are all biomarkers.
Targeted Therapy
A treatment specifically designed to act on a defined molecular target โ for example, trastuzumab targeting HER2 protein, or pembrolizumab targeting PD-1. Targeted therapies are only effective when the relevant biomarker is present โ making testing before treatment critical.
Biomarker Testing Methods Explained
Different biomarkers require different testing technologies. Understanding which method was used for which result helps patients verify that testing was done correctly.
| Testing Method | What It Detects | Common Uses | Sample Type |
|---|---|---|---|
| IHC (Immunohistochemistry) | Protein expression levels on tumour cells | HER2, PD-L1, CLDN18.2, MMR proteins (MLH1, MSH2, MSH6, PMS2), ER/PR (breast) | FFPE tissue biopsy/resection |
| ISH / FISH / CISH | Gene amplification or translocation | HER2 gene amplification (IHC 2+ confirmation), ALK, ROS1 rearrangements | FFPE tissue |
| PCR (Polymerase Chain Reaction) | Specific mutations, MSI status | KRAS/NRAS/BRAF mutation, MSI-H, EGFR mutation (ctDNA) | Tissue or blood (ctDNA) |
| NGS (Next-Generation Sequencing) | Hundreds of gene mutations simultaneously | Comprehensive tumour profiling โ KRAS G12C, FGFR, PIK3CA, HRD, TMB, MSI | Tissue (preferred) or blood |
| Liquid Biopsy (ctDNA) | Circulating tumour DNA fragments in blood | Treatment monitoring, resistance mutation detection, recurrence surveillance | Blood (plasma) |
| RNA Sequencing / Gene Expression | Gene expression patterns and fusion transcripts | NTRK fusion, RET fusion, HER2 amplification (alternate), tumour subtyping | Fresh or FFPE tissue |
Essential Biomarker Tests by Cancer Type
A practical reference showing which biomarker tests should be performed at diagnosis for each major cancer type โ and which treatment decisions they inform.
| Cancer Type | Essential Biomarkers | Treatment Decisions Informed |
|---|---|---|
| Gastric / GEJ Cancer | HER2 (IHC+ISH), CLDN18.2, PD-L1 CPS, MSI/MMR, FGFR2b | Trastuzumab, T-DXd, zolbetuximab, nivolumab/pembrolizumab, bemarituzumab trial |
| Non-Small Cell Lung | EGFR, ALK, ROS1, KRAS G12C, MET ex14, PD-L1 TPS, TMB | EGFR TKIs, ALK inhibitors, sotorasib, tepotinib, pembrolizumab |
| Colorectal Cancer | KRAS/NRAS/BRAF, MSI/MMR, HER2, EGFR expression | Cetuximab/panitumumab eligibility, pembrolizumab (MSI-H), T-DXd trial (HER2) |
| Breast Cancer | ER, PR, HER2 (IHC+ISH), BRCA1/2, PIK3CA, PD-L1 | Hormone therapy, trastuzumab/T-DXd, olaparib, alpelisib, pembrolizumab (TNBC) |
| Hepatocellular Carcinoma | PD-L1, AFP, HBV/HCV status | Atezolizumab + bevacizumab, nivolumab โ viral status informs treatment timing |
| Cholangiocarcinoma | IDH1/2, FGFR2 fusion, HER2, BRAF V600E, PD-L1 | Ivosidenib (IDH1), pemigatinib (FGFR2), targeted/IO combinations |
| Cervical Cancer | PD-L1 CPS, HPV type | Pembrolizumab (CPS โฅ1, first-line platinum-eligible) |
How to Ensure Your Biomarker Testing Is Complete
These are the practical steps patients and families can take to verify their biomarker testing is adequate for treatment decision-making.
- 1
Confirm Which Tests Were Performed
Ask your oncologist specifically which biomarker tests were ordered on your biopsy or resection specimen โ and review the pathology and molecular pathology reports yourself. Key omissions are common: CLDN18.2 in gastric cancer, MSI in all GI cancers, and FGFR2b in gastric cancer are frequently missed.
- 2
Verify Testing Was Done Correctly
Some tests require specific antibody clones, scoring systems, or technical protocols โ HER2 IHC in gastric cancer uses different criteria than breast; PD-L1 requires a specific pharmDx-validated assay for certain drug approvals. Incorrect methodology can produce misleading results.
- 3
Request Additional Testing on Archival Tissue
If biomarker testing is incomplete, most missing tests can be performed on the archived FFPE tumour block from the original biopsy or resection โ tissue that was already collected but not tested for all relevant markers. CancerFax can advise on which tests are possible on archival material.
- 4
Consider Comprehensive NGS Profiling
If standard biomarker panels are complete but the cancer has progressed or few treatment options remain, comprehensive NGS (next-generation sequencing) from a validated laboratory identifies rare actionable mutations, TMB, HRD, and other markers that could unlock clinical trial eligibility.
- 5
Re-Test at Progression
Biomarker status can change at disease progression โ HER2 amplification can be lost, new resistance mutations emerge, and MSI status can occasionally shift. Re-biopsy and re-profiling at first progression is increasingly standard practice and should be considered before committing to the next line of treatment.
Precision Oncology โ Key Numbers
Quantitative context for the clinical impact of biomarker testing and precision oncology.
- ~40%Proportion of cancer patients with at least one actionable mutation detectable by NGSA substantial minority with targetable molecular alterations โ identified only through comprehensive profiling, not standard single-biomarker panels.
- 10โ15%Rate of changed pathological diagnosis on expert pathology reviewExpert re-review of pathology and biomarker testing changes or refines diagnosis in approximately 1 in 8 cases โ underscoring the value of specialist second opinions.
- 48 hrsCancerFax turnaround for biomarker completeness reviewWe review your full pathology and molecular report set and identify gaps within 48 hours โ fast enough to influence treatment decisions before your next oncology appointment.
More from the CancerFax Resource Library
Explore biomarker-specific guides for gastric cancer, immunotherapy eligibility, and how CancerFax helps patients navigate treatment decisions.
Frequently Asked Questions About Biomarker Testing
What is the difference between IHC and NGS testing?
IHC (immunohistochemistry) tests for the presence and level of a specific protein on tumour cells using antibody-based staining โ it is relatively fast, inexpensive, and widely available, but only tests one marker at a time. NGS (next-generation sequencing) sequences the DNA of hundreds or thousands of cancer-relevant genes simultaneously from a single sample โ providing a comprehensive mutational landscape including rare actionable mutations, TMB, HRD, and MSI. Both have important roles: IHC is used for standard biomarkers (HER2, PD-L1, CLDN18.2); NGS is used for comprehensive profiling when standard panels are complete but further options are being sought.
Can biomarker testing be done on a biopsy taken years ago?
Yes โ in most cases. Formalin-fixed paraffin-embedded (FFPE) tumour blocks can be stored for many years and used for IHC and DNA-based testing including NGS. The quality and quantity of extractable DNA declines over time and with certain tissue preparation methods, but archival tissue from 3โ5 years ago is generally adequate for most standard biomarker tests. CancerFax can advise on which tests are feasible on your specific archival material based on the biopsy date, specimen type, and storage method.
My NGS report shows a mutation. Does that mean I can get targeted therapy?
Not automatically. An NGS mutation finding is only clinically actionable if: there is an approved or investigational drug targeting that specific alteration, the drug has evidence of activity in your cancer type (not just in other cancer types where the mutation was discovered), and you meet the eligibility criteria for that therapy. CancerFax reviews NGS reports in the context of your specific cancer type and treatment history โ distinguishing truly actionable alterations from variants of uncertain significance.
How CancerFax Helps
CancerFax is a specialist cancer access and patient-navigation platform. We help patients and families understand their options, organise medical records, coordinate hospital communication, and support cross-border treatment planning where appropriate.
We help collect and organise reports, scans, pathology, biomarker results, and treatment history for structured case review.
We communicate with hospitals or trial teams to assess whether a case may be suitable for further screening.
We support appointment coordination, document submission, translation, and direct communication with international departments.
For international patients, we help with practical coordination โ travel planning, hospital admission guidance, and local support.
If this option is not suitable, we help explore other relevant treatments, clinical trials, or advanced care pathways.
From inquiry through to follow-up, our coordinators provide a single point of contact for the family.
CancerFax does not guarantee treatment access, eligibility, or clinical outcome. Our role is to help patients access accurate information, structured review, and appropriate specialist pathways.
Not Sure If Your Biomarker Panel Is Complete?
CancerFax reviews your pathology and molecular testing results to identify gaps โ and advises on which additional tests are most likely to reveal actionable treatment options for your specific cancer type.
This content is for informational purposes only and does not constitute medical advice. Always consult a qualified oncologist before making treatment decisions.