The so called "Triple Negative Breast Cancer" (TNBC) represents approximately 
15-20% of breast cancers. This acronym simply means that the tumour does not 
express oestrogen receptor (ER) and progesterone receptor (PR) and does not 
exhibit amplification of the human epidermal growth factor receptor 2 (HER2) 
gene. Despite this unambiguous definition, TNBCs are an heterogeneous group of 
tumours with just one common clinical feature: a distinctly aggressive nature 
with higher rates of relapse and shorter overall survival in the metastatic 
setting compared with other subtypes of breast cancer. Because of the absence of 
well-defined molecular targets, cytotoxic chemotherapy is currently the only 
treatment option for TNBC. In the last decades, the use of more aggressive 
chemotherapy has produced a clear improvement of the prognosis in women with 
TNBC, but this approach results in an unacceptable deterioration in the quality 
of life, also if some support therapies try to relieve patients from distress. 
In addition, there is the general belief that it is impossible to further 
improve the prognosis of TNBC patients with chemotherapy alone. In view of that, 
there is a feverish search for new "clever drugs" able both to rescue 
chemo-resistant, and to reduce the burden of chemotherapy in chemo-responsive 
TNBC patients. A major obstacle to identifying actionable targets in TNBC is the 
vast disease heterogeneity both inter-tumour and intra-tumour and years of study 
have failed to demonstrate a single unifying alteration that is targetable in 
TNBC. TNBC is considered the subtype that best benefits from the neoadjuvant 
model, since the strong correlation between pathological Complete Response and 
long-term Disease-Free-Survival in these patients. In this review, we discuss 
the recent discoveries that have furthered our understanding of TNBC, with a 
focus on the subtyping of TNBC. We also explore the implications of these 
discoveries for future treatments and highlight the need for a completely 
different type of clinical trials.