Stromal CD73 Expression in Breast Cancer: Subtype-specific Expression and its Prognostic Significance

Abstract

Background/Aim: Invasive ductal carcinoma (IDC) is classified into distinct subtypes with varying prognoses and treatment sensitivities. For instance, triple-negative breast cancer (TNBC) is associated with poorer outcomes than other subtypes. We have previously reported the role of interstitial CD73 in tumor invasion and its correlation with prognosis in other cancers. This study aimed to investigate the expression of stromal CD73 (sCD73) in IDC and its potential prognostic significance. Patients and Methods: We analyzed 61 cases of human epidermal growth factor receptor 2-negative IDC, including TNBC and hormone receptor-positive (luminal-type) cases, treated surgically at our institution from 2005 to 2010. Cases that received preoperative drug therapy were excluded. CD73 expression was evaluated by immunostaining of the tumor stroma. Results: sCD73 expression was observed in 70% of all cases, with a significantly higher rate in TNBC (93%) compared with luminal breast cancer (48%). High sCD73 expression was associated with poor prognosis in terms of overall survival (OS) and disease-free survival (DFS) across all cases. In patients with luminal breast cancer, high sCD73 expression was also indicative of poor prognosis with respect to both OS and DFS. Conclusion: High expression of sCD73 is associated with poor prognosis in IDC, particularly in luminal breast cancer. Further research is needed to establish sCD73 as an independent prognostic factor.