Distribution of molecular breast cancer subtypes among Tunisian women and correlation with histopathological parameters: a study of 194 patients.

According to the immunohistochemical test of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (Her-2), breast cancer can be divided into 4 molecular subtypes: luminal A, luminal B, Her-2, and basal-like. The purpose of this study is to correlate these subtypes with clinicopathological features. We have selected from the files of our Pathology Department 194 breast carcinomas which had already been studied for ER, PR, and Her-2, diagnosed between January 2008 and October 2009. The cases were classified into 4 molecular subtypes. The clinicopathological characteristics of each subtype were compared. The luminal A subtype was the most prevalent (51.5%). The basal-like and Her-2 subtypes were significantly correlated to a large tumor size, a high tumor grade, and a high-volume nodal involvement (≥4). On multivariate analysis, patients with the Her-2 and basal-like subtypes were 4.2 (95% CI, 1.3-13.5) times more likely to have developed metastases in four or more lymph nodes than those with luminal tumors. Our analysis revealed that the Her-2 and basal-like subtypes are correlated with factors associated with a poor prognosis. The luminal A subtype is the commonest subtype, showing that breast cancer in Tunisia has no aggressive phenotype.