Proteomics as a Guide for Personalized Adjuvant Chemotherapy in Patients with Early Breast Cancer

Proteomics allows for better understanding of the function and regulation of cancer cells mediated by intra- and extracellular signaling networks. Integrating such information with clinicopathological characteristics of the tumor may lead to either detection of disease biomarkers useful to differentiate high-from low-risk patients, or to identification of new drug targets. Adjuvant chemotherapy is currently a personalized treatment strategy, especially for breast cancer (BC) patients, and the risk assessment of each patient influences its use because the benefit strictly correlates with the level of risk. Luminal A BCs are endocrine therapy (ET)-sensitive but exhibit low sensitivity to chemotherapy, while luminal B cancers, according to the Ki-67 proliferation rate may require for chemotherapy in addition to ET, and HER2-positive tumors derive benefit from adjuvant chemotherapy containing an anthracycline, a taxane and trastuzumab for one year. Triple-negative BCs have a high degree of genomic instability exhibiting a more aggressive clinical course with respect to other types of BC, and the anthracycline-taxane regimen constitutes the standard approach. Studies considering the use of targeted approaches (drugs), including poly (ADP-ribose) polymerase (PARP-1), vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR) inhibitors, or EFGR and HER2 blockers, are still under evaluation. In the genomic era, promising new targeted-therapies are worthy of further investigation, and mTOR inhibitors have been used for patients with high-risk ER-positive and HER2-negative tumors. In the near future, genetic and molecular profiling of BC will help to better-categorize patients, determine the choice of chemotherapy in low-risk, or intensify the treatment in high-risk cancer patients, eventually revealing new targeted agents.