Assignment of tumor subtype by genomic testing and pathologic-based approximations: implications on patient's...

Area of Science:

• Oncology
• Genomics
• Biomarkers

Background:

• Breast cancer subtyping is crucial for treatment but can be determined by genomic testing or pathology, which are not always equivalent.
• The clinical relevance and comparative prognostic value of these different breast cancer classification methods require further investigation.

Purpose of the Study:

• To compare the agreement and prognostic significance of pathology-based versus genomic (PAM50 + claudin-low predictor) breast cancer subtyping.
• To evaluate the impact of different subtyping methods on predicting overall survival (OS) and relapse-free survival (RFS) in patients receiving neoadjuvant chemotherapy.

Main Methods:

• A randomized trial involving 94 patients receiving neoadjuvant doxorubicin or docetaxel.
• Tumor subtyping using both pathology and gene expression (PAM50 + CLP).
• Statistical analysis included Kappa coefficient for agreement and Cox proportional hazards models for prognostic evaluation.

Main Results:

• Moderate agreement (κ = 0.551) was observed between pathology-based and PAM50 classifications.
• Both methods were prognostic for OS and RFS, but PAM50 + CLP provided superior prognostic information for OS.
• Triple-negative and basal-like tumors showed worse OS with doxorubicin, while claudin-low tumors had better OS when treated with doxorubicin compared to basal-like tumors.

Conclusions:

• Methodology for breast cancer subtyping impacts classification results, potentially influencing patient management and therapeutic strategies.
• Genomic subtyping, particularly PAM50 + CLP, offers enhanced prognostic value for overall survival compared to traditional pathology-based methods.
• Understanding these classification differences is vital for optimizing treatment selection and improving patient outcomes in breast cancer care.