This is a growth factor protein, which is over-expressed in different types of human cancers, including breast, ovarian, lung, gastric and oral cancers.11 In 1987, the HER-2/neu proto-oncogene was revealed to be amplified and over-expressed in 20–30% of invasive breast cancers, and also shown to be associated with poorer outcome and shortened survival. In addition, HER-2/neu-positivity is thought to predict the likelihood of resistance or sensitivity to some conventional hormonal therapies like tamoxifen. Herceptin (trastuzumab), a recombinant humanised anti-HER-2/neu monoclonal antibody has been shown to improve outcomes for women with metastatic breast cancer, either alone or in combination with chemotherapy.
Triple negative breast cancer (TNBC)
This is breast cancer, which is negative for oestrogen, progesterone and HER-2/neu receptors, and has been noticed to occur in certain categories of patients mostly from lower socio-economic groups or deprived communities.4 It makes up to 20% of all breast cancers and currently has no standard treatment.14 This type of breast cancer (TNBC) has also been associated with higher recurrence rates, faster growth and poorer prognosis, compared with other conventional breast cancers; and it is only sensitive to chemotherapy.
In addition to that, TNBC is associated with inactivation of BRCA1 and over-expression of the epidermal growth factor receptor (EGFR), which makes it sensitive to anti-EGFR therapies currently under trial.16 Novel molecular-targeted treatments are currently being developed, but still undergoing trials.17 However, a sub-group of patients have recently been described who have chemo-resistant TNBC, and therefore, other therapeutic manoeuvers such as targeting AR activation or cancer stem cells may be have to be considered in future