BackgroundUpregulated gene 4 (URG4) is a recently described oncogene that upregulates cell proliferation. Its overexpression has been identified in many malignancies, and it is thought to be related to tumour progression, angiogenesis, metastasis and the recurrence of many cancers. This is the first study to show its expression in breast cancer patients and its association with clinicopathological characteristics in these patients.MethodsFifty invasive ductal breast carcinoma cases and 25 control cases were included in the study. Tumourous tissues and control tissues were assessed molecularly for quantification of mRNA expression of URG4 and immunohistochemically for protein expression of URG4.ResultsThe mean ages of the patients and controls were 54.311.3 and 38.9 +/- 9.7 years, respectively. The expression levels of URG4 mRNA in tumour tissues were higher compared to control breast tissues (p=0.023). An immunohistochemical assessment suggested that URG4 is strongly expressed in normal breast tissues and lower-grade (grades I and II) ductal carcinomas of the breast, but it is weakly expressed in high-grade (grade III) ductal breast carcinomas. Additionally, the immunohistochemical and molecular expression results of URG4 were relevant to most prognostic parameters (tumour size, oestrogen and progesterone receptor status, HER2 status and Ki67 proliferative index) for breast cancer. However, unlike the immunohistochemical studies, the molecular studies revealed that there was no significant difference in URG4 expression for different grades of tumour tissues.Conclusion The literature data suggest that URG4 overexpression is associated with poor prognosis in many types of cancer. Conversely, our results in breast cancer specimens indicate that URG4 overexpression in breast ductal carcinomas is significantly associated with good prognostic parameters. Nevertheless, these preliminary findings should be confirmed by further studies.