Background: Breast cancer is the most common diagnosed cancer among females and the leading 
cause of cancer deaths. Immunohistochemical expression of PDL1 has been associated with bad 
prognosis in various malignancies including breast cancer. Methods: Immunohistochemical staining 
of PDL1 was performed on 60 tissue specimens of invasive ductal carcinoma by using the avidin 
biotin-peroxidase complex method with diaminobenizidine (DAB) chromogen detection system.
Results: High expression of PDL1 was detected in tumor cells in 51.7% of cases. High expression was 
statistically significant with high tumor grade (p<0.001), LVI (p=0.002), infiltrated tumor margins 
(p=0.039), LN metastasis (p=0.013), ER- status (p=0.012), PR- status (p=0.002) and high Ki-67 
expression (p=0.031). Conclusion: High PDL1 expression in tumor cells was associated with poor 
prognostic factors as high tumor grade, LVI, infiltrated tumor margins, LN metastasis and high Ki-67 
expression. Overexpression of PDL1 is related to bad outcome of invasive ductal carcinoma cases.