Breast Cancer Molecular Subtypes and Associations with Clinicopathological Characteristics in Iranian Women, 2002-2011

Breast cancer is a heterogeneous disease that is affected by ethnicity of patients. According to hormone receptorstatus and gene expression profiling, breast cancers are classified into four molecular subtypes, each showingdistinct clinical behavior. Lack of sufficient data on molecular subtypes of breast cancer in Iran, prompted usto investigate the prevalence and the clinicopathological features of each subtype among Iranian women. Atotal of 428 women diagnosed with breast cancer from 2002 to 2011 were included and categorized into fourmolecular subtypes using immunohistochemistry. Prevalence of each subtype and its association with patients’demographics and tumor characteristics, such as size, grade, lymph-node involvement and vascular invasion,were investigated using Chi-square, analysis of variance and multivariate logistic regression. Luminal A wasthe most common molecular subtype (63.8%) followed by Luminal B (8.4%), basal-like (15.9%) and HER-2(11.9%). Basal-like and HER-2 subtypes were mostly of higher grades while luminal A tumors were more ofgrade 1 (P<0.001). Vascular invasion was more prevalent in HER-2 subtype, and HER-2 positive tumors weresignificantly associated with vascular invasion (P=0.013). Using muti-variate analysis, tumor size greater than5 cm and vascular invasion were significant predictors of 3 or more nodal metastases. Breast cancer was mostcommonly diagnosed in women around 50 years of age and the majority of patients had lymph node metastasis atthe time of diagnosis. This points to the necessity for devising an efficient screening program for breast cancer inIran. Further, prospective surveys are suggested to evaluate prognosis of different subtypes in Iranian patients.