['Kruppel-like factor (KLF5) is a cell growth mediator in various epithelial cells. Higher KLF5 increases cell growth rate and leads to transformed phenotypes. Because tumor cell proliferation is tightly associated with tumor progression, and consequently, with survival of cancer patients, we wanted to examine the prognostic value of KLF5 gene expression for patients with breast cancer.', 'The gene expression levels of KLF5, ER, PR, HER2, and MKI67 were quantified in the tumor tissues of 90 patients with breast cancer and correlated with disease-free survival and overall survival of the patients. The correlations of gene expression between KLF5 and ER, PR, HER2, and MKI67 were analyzed. In addition, KLF5 expression was also compared with clinical data and age of patients.', 'Statistically significant correlations were found between gene expression of KLF5 and both disease-free survival (univariate analysis) and overall survival (univariate and multivariate analysis). Patients with higher KLF5 expression had shorter disease-free survival and overall survival time, whereas patients with lower KLF5 expression had better survival. Moreover, KLF5 was also found to be positively correlated with HER2 and MKI67, and negatively correlated with age of the patients at diagnosis.'] Is expression of KLF5 a prognostic factor for disease-free survival and overall survival in patients with breast cancer?