Objective To explore the relationship between the classification of triple-negative breast cancer (TNBC) and its clinicopathological characteristics and prognosis.

Methods A total of 110 TNBC tissue samples were collected. The expressions of androgen receptor, cluster of differentiation 8, forkhead box C1, and doublecortin-like kinase 1 (DCLK1) in TNBC tissues were detected using immunohistochemistry. The molecular classification of TNBC was performed, namely LAR, IM, BLIS, MES, UC. The correlation between this classification and the pathological characteristics of TNBC patients was analyzed.

Results The molecular classification of TNBC was significantly correlated with histological grade (P ＜ 0.01). The proportion of histological grade Ⅲ in IM type and BLIS type was higher than that of grade Ⅰ–Ⅱ (P ＜ 0.05). Patients with Ki-67 ＞ 30% and patients with TNM stage Ⅲ had shorter recurrence-free survival (P ＜ 0.05), while those with histological grade Ⅲ had shorter overall survival (P ＜ 0.01). Multivariate Cox regression analysis showed that Ki-67 and TNM stage were independent prognostic factors for postoperative recurrence and metastasis in TNBC patients (P ＜ 0.05).

Conclusions The molecular classification of TNBC is significantly correlated with histological grade. IM type and BLIS type are characterized with higher histological grades. Patients with Ki-67 ＞ 30% and patients TNM with stage Ⅲ are prone to recurrence and metastasis, and those with histological grade Ⅲ have a poorer prognosis.