INTRODUCTION

• Young women with breast cancer (YWBC; ≤40 years) have a more aggressive clinical course and younger age of diagnosis is associated with a poorer prognosis.
• The genomic landscape of YWBC remains largely unknown with the exception of predisposing germline mutations in BRCA1/2 (11-23% of YWBC).
• We assessed molecular profiling data to explore patterns of biomarkers that may provide insight into the aggressive biology observed in younger patients.

METHODS

• We explored molecular features in tumor subtypes of YWBC and older women with breast cancer (OWBC; ≥65 years).
• Somatic genomic profiles of 1879 breast tumors collected from 2013-2017 were assessed retrospectively and included in a de-identified data analysis if ER, PR and HER2 (immunohistochemistry [IHC] and/or in situ hybridization [ISH]) were available.
• Testing included IHC, ISH and massively parallel sequencing assays (next generation sequencing [NGS]) at a CLIA-certified laboratory (Caris Life Sciences, Phoenix, AZ).
• Pearson’s chi-square and regression analysis were utilized for comparisons and significance defined as p < 0.05.

CONCLUSIONS

• There are distinct differences in the biology between young and older women with breast cancer.
• These molecular changes may contribute to increased understanding of breast cancer tumor biology and refinement of treatment strategies in younger and older women with breast cancer.