Predictive factors of hormonal therapy in breast cancer

Breast cancer is a hormone-dependent cancer, and the presence of estrogen receptor (ER) and progesterone receptor (PgR) in tumors is used clinically to predict the likelihood of response to hormonal therapies. This review describes the roles of (1) hormone related factors (ER, PgR, phosphorylated ER, ERbeta, aromatase), (2) growth related factors (HER2, Ki67, p53), (3) ER cofactors (AIB1, NcoR1), (4) estrogen dependent genes derived from gene expression profiling (HDAC6, IGFBP4/5), and (5) gene profiling using cDNA microarray. There are, however, considerable methodological difficulties in identifying useful predictive factors but on the basis of current evidence other biomarkers add little additional information. The prospective and multi-centered analyses will be warranted to develop the predictive factors for directing use of these therapies.