Abstract: Signal transducer and activator of transcription 5 (STAT5) is a member of signal transducer and activator of transcription family, which has two highly homologous subtypes: STAT5A and STAT5B. STAT5 is widely involved in various biological processes such as cell proliferation, differentiation, apoptosis, senescence, hematopoiesis and immunity. The dysregulation of STAT5 is closely related to the occurrence and development of malignant tumors such as leukemia, breast cancer, prostate cancer, melanoma and thyroid cancer. STAT5 can also affect tumor radiotherapy and chemotherapy as well as prognosis of patients. Nowadays, STAT5 has become a key target for cancer treatment. Targeting STAT5 could increase the radiosensitivity of prostate cancer, head and neck cancer and other tumors, which provided a new strategy for tumor treatment. This article reviews the role of STAT5 in several malignant tumors and strategies of targeting STAT5.

Key words: STAT5 transcription factor, neoplasms, molecular targeted therapy, radiotherapy, STAT5A, STAT5B; review