First report on molecular breast cancer subtypes and their clinico-pathological characteristics in Eastern Morocco: series of 2260 cases.

BACKGROUND: Breast cancer is the most frequent malignancy among women in Eastern Morocco. In this paper, we provide the first report on molecular breast cancer subtypes in this region. This is the largest population-based study on breast cancer among Moroccan women.

METHODS: We analyzed 2260 breast cancer cases diagnosed at the Hassan II Regional Oncology Center between October 2005 and December 2012. Clinico-pathological and therapeutic features were studied. Molecular subtypes were determined and their associations with the clinico-pathological characteristics of the tumors were examined.

RESULTS: The mean age at diagnosis was 48.7 years ±11.4. Invasive ductal carcinoma was the predominant histological type (77.1%), followed by lobular invasive carcinoma (15.3%). The mean size of breast tumors was 3.5 cm ± 1.96, and 84% of our patients are diagnosed with tumors of more than 2 cm. Histological grade II tumors were the most frequent (70.4%), followed by advanced histological grade (18%). Lymph node positive tumors were observed in 64.8% of cases and 29.3% of patients had distant metastasis. Most tumors were hormone receptor-positive (73%) and 28.6% were HER2 positive. 86.1% of patients with hormone receptor-positive breast cancer were given hormone therapy, while 68.9% of patients with HER2+ breast cancer received targeted therapy with Herceptin. Luminal A was the commonest molecular subtype, followed by Luminal B, Triple Negative and HER2. The highest prevalence of premenopausal patients was observed in Triple Negative subtype (72.2%), followed by HER2 (64.1%), Luminal B (62.2%), and Luminal A (55.1%). Luminal B subtype had a poorer prognosis than Luminal A. Compared with Triple Negative, HER2 subtype tend to spread more aggressively and is associated with poorer prognosis.

CONCLUSIONS: Unlike Western countries, breast cancer occurs at an earlier age and is diagnosed at a more advanced stage in Eastern Morocco. In this region, hormone receptor-positive tumors are predominant and so the majority of breast cancer patients should benefit from hormone therapy. HER2 subtype presents an aggressive tendency, suggesting the importance of anti-HER2 therapy. This study will contribute in developing appropriate screening and cancer management strategies in Eastern Morocco.