Molecular profiling comparison of breast cancer subtypes in young women and older women


Antoinette R. Tan, Rebecca Feldman, James T. Symanowski, Qing Zhang, Julie G. Fisher, Lejla Hadzikadic-Gusic, Richard L. White Jr., Edward S. Kim


  • 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.


  • 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.


  • 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.

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