Molecular Profiling of Breast Cancer

Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death in females worldwide, accounting for 23% (1.38 million) of the total new cancer cases and 14% (458,400) of the total cancer deaths in 2008 (Jemal et al. 2011; Jemal, Siegel, and Ward 2010). In the U.S., 234,190 new cases and 40,730 deaths are estimated for 2015 (ACS 2015). Traditionally, treatment decisions have been based on tumor histology and the status of three main biomarkers: ER (estrogen receptor 1, or ESR1), PR (progesterone receptor, or PGR), and HER2 (erb-b2 receptor tyrosine kinase 2, or ERBB2, also known as neu). Despite significant improvements in the treatment of breast cancer, new therapies and treatment strategies are needed.


Hormone Signaling Pathway





PI3K/AKT1/MTOR Pathway


  • AKT1 mutations


  • PIK3CA mutations


  • PTEN mutations


Receptor Tyrosine Kinase/Growth Factor Signaling Pathway

ERBB2 (HER2/neu)




Cell Cycle Control/DNA Damage

CCND1 (Cyclin D1)

  • Cyclin D1 amplification


  • CDK4 alterations


  • CDK6 alterations


  • RB1 alterations


  • TP53 alterations


Contributors: Justin M. Balko, Pharm. D., Ph.D., Ingrid A. Mayer, M.D., M.S.C.I., Mia Levy, M.D., Ph.D., Carlos L. Arteaga, M.D.

Suggested Citation: Balko, J., I. Mayer, M. Levy, C. Arteaga. 2015. Molecular Profiling of Breast Cancer. My Cancer Genome (Updated July 6).

Last Updated: July 6, 2015

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