A new review has been published that summarizes current knowledge concerning estrogen receptor positive/progesterone receptor negative (ER+/PR-) breast cancer. ER+/PR- tumors are a distinct subset of breast cancer known to have aggressive behavior and tamoxifen resistance despite being ER+.
They are categorized as luminal B tumors (estrogen receptor positive, often with low tumor grade, but with higher proliferation than other estrogen receptor positive tumors), with greater DNA instability than ER+/PR+ tumors.
High growth factor signaling contributes to the aggressive behavior of this type of breast cancer. The absence of PR is attributable to low circulating estrogen, low levels of nuclear ER, as well as variables pertaining to growth factors. ER+/PR- patients tend to have greater expression of human epidermal growth factor receptor (HER1 and HER2) and active growth factor signaling.
Currently, aromatase inhibitors, fulvestrant (Faslodex), and chemotherapy are the most common treatment approaches for ER+/PR- breast cancer patients. Overcoming tamoxifen resistance with targeted therapies such as gefitinib (Iressa), an epidermal growth factor receptor (EGFR) inhibitor, are being tried. Strategies involving short courses of tamoxifen have also been proposed to prevent recurrence of ER+/PR- breast cancer.
The authors conclude that understanding the interplay between molecular endocrinology and tumor biology has provided experimental therapeutic insights, and continued work in this area holds the promise of future advances in prognosis.
Please see our article on breast cancer diet for ER+/PR- patients and survivors for more information.
Selected breast cancer studies
The prognostic significance of single hormone receptor positive metastatic breast cancer: An analysis of three randomised phase III trials of aromatase inhibitors
Stuart-Harris R, Shadbolt B, Palmqvist C, Chaudri Ross H. The prognostic significance of single hormone receptor positive metastatic breast cancer: An analysis of three randomised phase III trials of aromatase inhibitors. The Breast. Elsevier BV; 2009; 18:351-355 10.1016/j.breast.2009.09.002
Breast Cancer Risk Factors Defined by Estrogen and Progesterone Receptor Status: The Multiethnic Cohort Study
Setiawan VW, Monroe KR, Wilkens LR, Kolonel LN, Pike MC, Henderson BE. Breast Cancer Risk Factors Defined by Estrogen and Progesterone Receptor Status: The Multiethnic Cohort Study. American Journal of Epidemiology. Oxford University Press (OUP); 2009; 169:1251-1259 10.1093/aje/kwp036
ER+ PR- breast cancer defines a unique subtype of breast cancer that is driven by growth factor signaling and may be more likely to respond to EGFR targeted therapies
Finn RS, Dering J, Ginther C, Press M, Forbes J, Mackey J, et al. ER+ PR- breast cancer defines a unique subtype of breast cancer that is driven by growth factor signaling and may be more likely to respond to EGFR targeted therapies. Journal of Clinical Oncology. American Society of Clinical Oncology (ASCO); 2006; 24:514-514 10.1200/jco.2006.24.18_suppl.514
Antidepressant use and breast cancer risk
Chien C, Li CI, Heckbert SR, Malone KE, Boudreau DM, Daling JR. Antidepressant use and breast cancer risk. Breast Cancer Research and Treatment. Springer Science and Business Media LLC; 2005; 95:131-140 10.1007/s10549-005-9056-0