Prognostic Values of Immunohistochemical Expression of RAD51 and NR1D1 in Tissues of Triple-Negative Breast Cancer (TNBC), Aclinicopathological study.

Background: defects in DNA damage response might contribute to metastatic potential of TNBC. Many of genes identified RAD51 controls repair of DNA damage in cancer cells. RAD51 was incriminated in causing excess DNA damage in non-malignant cells thus could initiate cancer initiation, progression, metastases and resistance to therapy. But its roles in TNBC were not fully clarified. NR1D1 was reported to be associated with breast carcinogenesis but its role in progression of TNBC was not fully assessed. we aimed to assess expression of two DNA damage response biomarkers; RAD51 and NR1D1 in tissues of TNBC then correlate their expression with pathological data, metastatic potential, tumor recurrence and patients survival. Methods : evaluated RAD51 and NR1D1 expression in cases with TNBC using immunohistochemistry in the tissues derived from sixty cases with TNBC. We surveyed patients for about 3 years for detecting disease recurrence free survival rate and overall survival rate. Results: Higher RAD51expression was significantly associated advanced stage (P < 0.001), lymphatic spread (P=0.027), and larger tumor size (P=0.001). Lower NR1D1expression was significantly associated with advanced stage (P < 0.009), presence of lymph nodes metastases (P= 0.001), and Higher expression of RAD51 and lower expression of NR1D1 were associated with high incidence of recurrence of the tumor (P < 0.001). Also ,they were associated with unfavorable RFS rate (P=0.001) and unfavorable OS rate (P=0.019 and P=0.012, respectively). Conclusion: overexpression of RAD51 and lesser expression of NR1D1 was associated with aggressive phenotype, unfavorable outcome and unfavorable survival rates in (TNBC )breast cancer.