What is Prosigna?
Prosigna is a gene expression test (also known as PAM50-ROR) that analyzes the activity of 50 genes to predict the risk of recurrence in patients with early-stage breast cancer, specifically for those with hormone receptor-positive, HER2-negative disease. 1
Overview and Technical Details
- Prosigna is manufactured by NanoString Technologies (Seattle, WA) and uses the PAM50 gene signature to assess the risk of cancer recurrence 1
- The test analyzes RNA extracted from formalin-fixed, paraffin-embedded (FFPE) tumor tissue samples 2
- It provides both a Risk of Recurrence (ROR) score and classifies tumors into intrinsic molecular subtypes (Luminal A, Luminal B, HER2-enriched, or Basal-like) 1, 3
Clinical Applications
- Primarily used in postmenopausal women with hormone receptor-positive, HER2-negative early breast cancer to guide adjuvant therapy decisions 1
- The test has achieved a Level of Evidence [I, B] according to biomarker guidelines for its prognostic value in ER-positive breast cancers 1
- Helps determine which patients might benefit from adjuvant chemotherapy versus those who can safely avoid it 1, 3
Evidence-Based Recommendations
Recommended Use:
- For patients with ER/PgR-positive, HER2-negative (node-negative) breast cancer: Clinicians may use the PAM50-ROR score in conjunction with other clinicopathologic variables to guide decisions on adjuvant systemic therapy 1
- Evidence quality: high
- Strength of recommendation: strong
Not Recommended:
- For patients with ER/PgR-positive, HER2-negative (node-positive) breast cancer 1
- For patients with HER2-positive breast cancer 1
- For patients with triple-negative breast cancer 1
Clinical Impact
- Studies show that Prosigna results can change treatment decisions in approximately 18-28% of cases 3, 4
- In a French multicenter study, there was a 25% discordance rate between immunohistochemistry-based subtyping and Prosigna molecular subtyping 3
- The test has been shown to reduce variability in chemotherapy recommendations between different hospitals, particularly for patients with intermediate clinical risk 4
Limitations and Considerations
- Sample preparation approach can influence the ROR score results - macrodissected FFPE tissue versus fresh-frozen bulk tissue may yield different results 2
- While validated in postmenopausal patients, limited data exists regarding its use in premenopausal patients 5
- There is only moderate correlation between Prosigna scores and Ki-67 proliferation marker results (correlation coefficient of 0.51) 5