Immunohistochemical expression of RUNX3 and p21WAF1/CIP1 and its correlation with clinicopathologic parameters in breast carcinoma of Egyptian women

Background: RUNX3 is a tumor suppressor involved in many cancers. RUNX3 regulation is complex; it can both repress and activate p21WAF1/CIP1. The cyclin-dependent kinase inhibitor p21waf1 is a key regulator of progression from the G1 to the S-phase of cell cycle. Previous studies on the prognostic value of RUNX3 and p21waf1 in breast carcinoma revealed conflicting results. To date, no immunohistochemical studies have been performed to assess the possible association between them in breast carcinoma. The aim of this study is to evaluate the immunohistochemical expression of RUNX3 and p21waf1 and investigate its association with clinicopathological prognostic parameters and to assess the possible relationship between them. Methods: A retrospective immunohistochemical study was conducted on 78 invasive ductal breast carcinoma cases using RUNX3 and p21waf1. Statistical analysis was performed. Results and Conclusion: The current study reports for the first time the relationship between RUNX3 and p21waf1 immunohistochemical expression in breast cancer; there was a highly statistically significant relation between RUNX3 and p21waf1 expressions (P=0.001), and a moderate significant agreement (kappa =0.467) between them. The two markers are statistically related to established prognostic clinicopathologic parameters suggesting a role in prognosis; RUNX3 showed high statistically significant relations with grade and lymph nodal status (P=0.001 for each), and statistically significant relations with tumor size and molecular subtypes (P=0.02, and P=0.04 respectively). p21waf1 showed highly statistically significant relations with grade, lymph nodal status, ER expression, PR expression, and molecular subtypes (P=0.001 for each), and a statistically significant relation with tumor size (P=0.045). The two markers also represent potential therapeutic targets for patients with breast cancer.