Objective To explore the expression of miRLet-7 family members in breast cancer and its correlation with overall survivals(OS)

and to find more effective molecular targets for breast cancer prevention and treatment. Methods Kaplan-Meier (KM) plotter online database was used to analyze the correlation among the expression of Let-7 family members (Let-7a

7b

7c

7d

7e

7f

7g

7i

miR-98

miR-202) correlated with overall survival (OS) and the prognosis and clinical pathological parameters of breast cancer patients

and Hazard ratio(HR)

95% confidence interval (CI)

and P value were determined.Results The study showed that the high expression level of Let-7a

Let-7b

Let-7c

Let-7e

Let-7f

Let-7g

miR-98 and the low expression level of miR-202 was associated with better OS for breast cancer patients (P＜0.05).We further assessed the prognostic value of Let-7 in different subtypes and clinical stage. The expression of Let-7a

Let-7b

Let-7f

Let-7g

miR-98

miR-202 was related to clinical stage (P＜0.05). Let-7a

Let-7b

Let-7c

Let-7e

Let-7f

Let-7g

miR-98 and miR-202 was related to lymph node status(P＜0.05).In triplenegative breast cancers (TNBC)

with breast cancer subtype

the expression of Let-7b

Let-7c

Let-7g and miR-202 was significantly correlated to overall survival(P＜0.05). Conclusion The Let-7 is significantly correlated with OS in breast cancer patients.The results suggested that members of the Let-7 have different values in predicting the prognosis of breast cancer. Among them

Let-7b

Let-7g and miR-202 are closely related with clinical stage and TNBC

and might promote development of Let-7 as targeted inhibitors for the treatment of breast cancer.