Breast cancer is not a single disease—it is a complex condition with many subtypes, each with unique biological characteristics. While traditional tests focus on tumour size, stage, and hormone receptor status, genomic profiling dives deeper, analysing the activity of specific genes in cancer cells. This powerful approach is transforming how doctors choose treatments and personalise care for patients.
Understanding Genomic Profiling
Genomic profiling (also called molecular profiling or gene expression profiling) involves analysing a tumour’s DNA or RNA to identify mutations, gene expression patterns, or other alterations that may influence cancer behaviour.
Rather than looking at the patient’s inherited genes (as in genetic testing), genomic profiling examines the tumour’s unique genetic changes—essentially a fingerprint of the cancer itself.
Common Tests Used in Breast Cancer
Several genomic tests are commonly used in early-stage, hormone receptor-positive (HR+), HER2-negative breast cancers, including:
- Oncotype DX®
- MammaPrint®
- Prosigna (PAM50)
- EndoPredict
Each test analyses different gene panels (typically 21 to 70 genes) to assess how likely the cancer is to recur and whether chemotherapy would be beneficial.
How Genomic Profiling Impacts Treatment Decisions
1. Determining Chemotherapy Benefit
One of the most significant contributions of genomic profiling is identifying patients who can safely avoid chemotherapy.
For example, the Oncotype DX Recurrence Score (0–100) helps predict:
- The risk of cancer recurrence within 10 years
- Whether a patient will likely benefit from adding chemotherapy to hormone therapy
Patients with low scores may only need hormone therapy, sparing them the side effects and risks of chemotherapy. Those with high scores are more likely to benefit from aggressive treatment.
2. Personalising Hormone Therapy Duration
Some genomic tests also guide decisions about how long a patient should stay on endocrine (hormone) therapy, which can last 5 to 10 years. For instance, EndoPredict and Prosigna may suggest whether extended therapy would help reduce long-term recurrence risk.
3. Guiding Clinical Trial Participation
Genomic profiling may identify specific mutations or gene expressions that make patients eligible for targeted therapies or experimental treatments in clinical trials.
4. Understanding Tumour Biology
Genomic data provide deeper insight into the tumour’s biology, helping to categorise breast cancer into molecular subtypes like:
- Luminal A
- Luminal B
- HER2-enriched
- Basal-like (Triple-negative)
This classification can influence treatment planning and prognosis.
Limitations and Considerations
While genomic profiling offers valuable guidance, it’s not appropriate for all breast cancer patients. Typically, it is used in early-stage, hormone receptor-positive, HER2-negative cases. It is not usually recommended for:
- HER2-positive or triple-negative breast cancers
- Patients with metastatic (stage IV) disease
- Patients who clearly need chemotherapy based on clinical features
Additionally, these tests complement—not replace—traditional pathology. Decisions are made using a combination of clinical, pathological, and genomic data.
Frequently Asked Questions (FAQs)
1. Is genomic profiling the same as genetic testing?
No. Genomic profiling analyses the tumour’s genes, while genetic testing looks at inherited gene mutations (like BRCA1/2) in a person’s DNA. Both tests serve different purposes and are often used together.
2. Will my insurance cover genomic testing?
Genomic profiling is available and routinely used in the NHS. Many insurance providers, including BUPA in the UK, cover genomic profiling like Oncotype DX if it is deemed medically necessary. Coverage may vary based on country, provider, and specific plan.
3. Can genomic profiling guarantee that my cancer won’t come back?
No test can offer a guarantee. Genomic profiling estimates risk, but recurrence can still occur even with a low score. It helps guide risk-reduction strategies, not eliminate risk entirely.
4. How is the test performed?
The test is done on a sample of the tumour tissue, typically from a biopsy or surgery. No additional procedure is needed for the patient.
5. Should I ask my doctor about genomic profiling?
Yes—if you have early-stage, hormone receptor-positive, HER2-negative breast cancer, it’s worth discussing with your oncologist. They can determine if you’re eligible and explain how the results may influence your treatment plan.
Conclusion
Genomic profiling represents a major advance in personalised breast cancer treatment. By analysing the genetic behaviour of tumours, it helps doctors tailor therapies to each patient’s unique cancer profile—minimizing unnecessary treatments while ensuring aggressive cancers receive the care they need. For many women, it means a more precise and confident treatment plan with better outcomes and quality of life.
Seni Mylvaganam
Consultant Oncoplastic Breast Surgeon
