Oncotype DX & Prognostic Gene Panels

What It Measures

• Oncotype DX: 21-gene expression profile generating a Recurrence Score (RS) 0–100
• MammaPrint: 70-gene expression profile classifying tumours as Low Risk or High Risk
• Proliferation genes (Ki-67 surrogate), ER/PR signalling genes, invasion genes, HER2 cluster
• Predicted 10-year distant recurrence risk with hormone therapy alone
• Predicted chemotherapy benefit (or lack thereof) — quantified by RS or risk category
• Extended: Prosigna (PAM50 subtype), EndoPredict, Breast Cancer Index for late recurrence

How It Works

RNA is extracted from fixed tumour tissue (FFPE block from surgical resection or core biopsy). Gene expression is measured using RT-PCR (Oncotype) or microarray (MammaPrint) across the defined gene panel. Results are processed by a validated algorithm and reported as a single score or risk category, with associated clinical decision guidance. Testing requires only a small amount of FFPE tumour block material.

• Early-stage (Stage I–III) ER+/HER2-negative breast cancer patients considering chemotherapy
• Node-negative or 1–3 node positive ER+ breast cancer patients
• Postmenopausal women with ER+ breast cancer (chemotherapy benefit is often low)
• Patients and oncologists wanting to avoid unnecessary chemotherapy toxicity
• Those seeking confirmation that hormone therapy alone is sufficient

Oncotype DX is one of the most robustly validated oncology biomarker tests in existence. The TAILORx trial (N=10,273, NEJM 2018) demonstrated that women with ER+/HER2- breast cancer and RS 0–25 derived no benefit from chemotherapy — a finding that spared millions of women from unnecessary treatment. MammaPrint was validated in the MINDACT trial (N=6,693, NEJM 2016). Both tests are recommended by NCCN (Category 1 evidence), ASCO, ESMO, and NICE. Oncotype DX is now used in over 100 countries and has influenced treatment decisions for over 1.5 million patients.

This list is not exhaustive. Ask your oncologist or integrative physician for locally available options.

• Validated specifically for ER+/HER2-negative breast cancer — not applicable to other subtypes
• Intermediate RS scores (16–25 in TAILORx) have nuanced chemotherapy benefit in premenopausal women — requires careful oncologist interpretation
• Does not replace clinical staging — tumour size, grade, and nodal status remain important
• MammaPrint and Oncotype DX do not always agree — specialist guidance needed when results conflict with clinical picture
• Not validated for metastatic or Stage IV breast cancer treatment decisions