Breast cancer has emerged as a grave danger in the last 50 years. It represented 35.1% of total cancer in women in Egypt National Cancer Institute (NCI) series. Changes in cell loss factor could have a major impact on tumor growth or regression. A large percentage of cell loss from tumors was due to apoptosis. P53 is a tumor suppressor gene that plays a critical role in preventing human cancer formation. In response to a variety of stress signals p53 becomes activated and induces cell cycle arrest and/or apoptosis. We Aimed to: 1. Study the immunohistochemical profile of p53 in breast carcinoma. 2. Assess its prognostic value in relation to clinico-pathological prognostic factors of breast carcinoma.

Subjects and Methods: This study included 45 specimens of breast carcinoma. Patient’s age, tumor size and local aggressive changes, history of recurrence and/or presence of distant metastasis were obtained. H&E stained sections were evaluated for the presence of benign breast disease, histo-pathological tumor type, and tumor grade, presence of in situ component, lymphocytic infiltration, lymphovascular invasion, and axillary lymph node status. P53 immunostaining was done to detect its expression using the avidin-biotin peroxidase method. Results: P53 was weakly expressed in 11% of areas of benign breast disease. P53 was negative in all cases of low grade ductal carcinoma in situ (DCIS), positive in 2/3 of intermediate grade DCIS, and positive in all cases of high grade DCIS. All grade I invasive breast carcinoma (IBC) were negative for p53, 50% of grade II and 91% of grade III IBC were positive for p53. P53 expression increased significantly with increased tumor grade of IBC (p<0.006), lymphovascular invasion (p<0.003) and lymphocytic infiltration (p<0.004). No significant correlation between p53 expression and lymph nodal status. Conclusions: P53 is an indicator for poor prognosis in breast cancer being positively correlated to tumor grade, presence of lymphovascular invasion. P53 may modulate the immune response in breast cancer being positively correlated with prominent lymphocytic infiltration.