Clinicopathological Behavior of Mucinous Breast Carcinoma in South of Iran: The Shiraz Breast Cancer Registry

Background: Mucinous breast carcinoma (MBC) is a subtype of breast cancer categorized by the presence of extracellular mucin and has more favorable prognosis than invasive carcinoma of no special type of breast cancer. The present study incorporates 27 years of practical experience from a breast disease research centerbased series of cases regarding MBC and invasive ductal carcinoma (IDC). Method: In this retrospective study, we studied the medical documents of 7,739 patients in the Breast Disease Research Center, Shiraz University of Medical Sciences, from December 1993 to January 2019. TNM data, demographic status, pathologic stage, histological grade, hormonal receptor data, recurrence, overall survival (OS), and disease-free survival (DFS) were reviewed. We also statistically evaluated the clinical and histopathological differences of pure, mixed MBC, and IDC using SPSS, version 21.0 (IBM, USA). P<0.05 was considered as statistically significant. Results: A total of 78 and 31 patients were observed to have pure and mixed MBC, respectively, and 5,774 breast cancer patients had IDC. The pure MBC group showed a lower histological grade and pathologic stage and a larger tumor size compared with mixed MBC (P<0.001). The pure MBC patients had significantly less perinural and lymphovascular invasion and had less HER-2 positive status in comparison with IDC patients (P=0.023). The DFS and OS did not differ the between groups. Conclusion: MBC is a rare diagnosis with a favorable prognosis due to low lymph node metastases.