Triple negative breast cancer refers to breast cancer that is negative for estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (Her-2). This type of breast cancer accounts for 10.0%-20.8% of all breast cancer pathological types and has special biological behavior and clinicopathological features, with poorer prognosis than other types. Epidemiology Triple-negative breast cancer is a subtype of breast cancer based on cell morphology and cell surface receptors, which has been clinically applied by gene microarray technology. Carey et al. showed that the incidence of triple-negative breast cancer in African American women under 50 years of age can be as high as 39%, compared to 16% in white women and 14% in postmenopausal African American women. Clinical and molecular pathological features Triple-negative breast cancer presents clinically as an aggressive disease process. Several clinical studies have shown that this type of breast cancer has a higher risk of distant metastases, with a higher incidence of visceral metastases than bone metastases and a higher incidence of brain metastases. Although the study by Dent et al. showed that the risk of distant metastasis in triple-negative breast cancer peaks at 3 years and may decline thereafter, it still has a poor prognosis and a higher risk of death. Kandel et al. showed that the median tumor size of triple-negative breast cancer was 2 cm, and 50% had lymph node metastases. Analysis of the pathological features revealed that the histological grade of these breast cancers is mostly grade 3, with a high percentage of cell proliferation, positive expression of c-kit, p53, epidermal growth factor receptor (EGFR), and positive basal cell markers cytokeratin (CK) 5/6 and 17. Some clinical features of triple-negative breast cancer are directly or indirectly derived from basal-like breast cancer. However, triple-negative breast cancer is a subtype of basal-like breast cancer and the two are not completely synonymous and not completely interchangeable. BRCA1-associated breast cancer also has some of the phenotypic and molecular pathological features mentioned above, and most scholars believe that there may be some correlation between it and triple-negative breast cancer. The BRCA1 gene has become one of the targets of research and studies have been initiated to target this target. Treatment There are no specific treatment guidelines for triple-negative breast cancer, so its treatment is generally performed according to the conventional standard of care for breast cancer. Some targeted prospective clinical trials based on molecular pathological abnormalities are currently underway, so most of the information is from retrospective studies or trial subgroup analyses. Chemotherapy Chemotherapy is more effective in triple-negative breast cancer compared to other types of breast cancer, but its prognosis remains poor if only standard treatment is routinely administered. Adjuvant chemotherapy The PACS01 trial is a phase III randomized clinical trial comparing the efficacy of a six-cycle FEC [fluorouracil + epirubicin + cyclophosphamide] regimen with a three-cycle FEC regimen sequenced with three cycles of docetaxel in patients with lymph node-positive breast cancer. At the 2006 American Society of Clinical Oncology (ASCO) annual meeting, investigators reported better metastasis-free survival (P=0,05) and overall survival (OS) rates (P=0,005) in patients with basal-like breast cancer in the sequential treatment arm of the trial. Thus, although basal-like breast cancer has a poor prognosis, it responds better to FEC sequential docetaxel chemotherapy. These results suggest that paclitaxel has some efficacy in triple-negative breast cancer, but the sequential dosing regimen may also contribute to its better efficacy. Since the results were obtained from subgroup analysis or retrospective analysis of the trials, they cannot be directly applied to the clinic yet and need to be confirmed by prospective studies. Neoadjuvant chemotherapy Carey et al. used the AC regimen to treat 107 patients with locally advanced breast cancer with neoadjuvant chemotherapy and found that the clinical efficiency of patients with Her-2-positive/ER-negative breast cancer reached 70%, basal-like breast cancer 85%, and luminal breast cancer (ER-positive) only 47% (P<0,0001), and the pathological Complete remission (pCR) rates were 36%, 27% and 7%, respectively (P=0, 01), but the rates of metastasis-free survival (P=0, 04) and OS (P=0, 02) were lower in the former two than in the latter, and poorer survival was significantly associated with higher recurrence in those with residual lesions (P=0, 003). Prognostic indicators Triple-negative breast cancer is a high-risk breast cancer with a poor overall prognosis and prognostic factors that differ from other types of breast cancer. a retrospective analysis of 1944 patients with invasive breast cancer by Rakha et al. found that tumor size, lymph node and androgen receptor status were the most useful prognostic markers in 16,3% of triple-negative breast cancers. a study by Nielsen et al. showed that Overexpression of Her-1 was associated with poorer survival regardless of lymph node status and tumor size, and c-kit expression, although also increased, was not found to correlate with prognosis.