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Breast cancer profile in Ras Al Khaimah, United Arab Emirates – a histopathological and immunohistochemical study
Breast cancer was the most frequently diagnosed cancer among United Arab Emirate (UAE) nationals in 2002, accounting for 23% of all cancers in women. However, few studies have examined the immunohistochemical profile and subtyping of breast cancer in UAE and their correlation with the established prognostic factors. The aim of this study is to evaluate the immunohistochemical expression of oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2)/neu, B-cell lymphoma 2 (Bcl-2), E-cadherin and p53 in primary breast carcinomas in Ras Al Khaimah (RAK) and analyse their expression in comparison with the established prognostic factors of breast cancer. We also attempt to classify breast cancer in the present cohort using immunohistochemical marker panels consisting of ER, PR and HER2, and to study the correlation with the other clinicopathological characteristics. The study included 28 patients with primary breast carcinomas diagnosed at the Department of Surgery, Saqr Hospital, RAK during the period 2001–10. Immunohistochemical staining for ER, PR, HER2/neu, Bcl-2, E-cadherin and p53 was carried out and the tumours were categorized into four subtypes: luminal A, luminal B, HER2 enriched and triple-negative breast cancer (TNBC). Expression of ER, PR, HER 2, Bcl-2, E-cadherin and p53 was observed in 12 (42.85%), 7 (25%), 6 (21.4%), 14 (50%), 12 (42.8%) and 5 (17.8%) tumours, respectively. Lobular carcinoma showed significantly higher expression of ER (80%, P = 0.05) and loss of E-cadherin expression in all cases (100%, P = 0.006); HER2 and p53 overexpression was more frequently found in invasive ductal carcinoma (66.6% and 80%, respectively), and poorly differentiated tumours exhibited loss of ER and PR (84.6%, P = 0.02, and 92.3%, P = 0.01, respectively), loss of E-cadherin expression and showed predominant expression of p53 (P = 0.029). There was a strong positive correlation between ER and PR expression and Bcl-2 expression (P = 0.002 and P = 0.03, respectively). A total of 40% of p53-expressing tumours showed HER2 overexpression compared with 82.61% displaying loss of both markers (P = 0.0001). The majority of p53-positive tumours were ER, PR and Bcl-2 negative (80%, 100% and 80%, respectively). The luminal A, luminal B, HER2-enriched and TNBC subtypes accounted for 39.29%, 10.71%, 10.71% and 39.29%, respectively. The immunohistochemical subtypes were significantly associated with histological grade (P = 0.03), in situ component (P = 0.04), American Joint Committee on Cancer (AJCC) stage (P = 0.02) and Bcl-2 expression (P = 0.001). Steroid hormone receptors and p53 expression were relatively lower than other series, whereas the expression of HER2, Bcl-2 and E-cadherin were consistent with the range reported in the literature. The molecular subtypes showed significant associations with tumour grade and stage, two of the well-established prognostic factors.