EPIDEMIOLOGICAL STUDY AND MOLECULAR BREAST CANCER SUBTYPES DISTRIBUTION AMONG WEST ALGERIAN PATIENTS

Purpose: Breast cancer is the leading cause of cancer death in women worldwide and in particular in Algeria. Breast cancer is a heterogenous disease; its molecular classification is based on gene expression and on proteomic profile to distinguish five major subtypes: luminal A, Luminal B, HER2+, basal like and normal like. We aimed in present study to achieve an epidemiologic study and to correlate molecular breast cancer subtypes with clinico pathological features among west Algerian patients.

Materials and Methods: We performed a retrospective study on 829 patients diagnosed with primary breast cancer who underwent initial surgery in west Algeria Hospitals between january 2008 and December 2013. Assessment of estrogen/progesterone receptors and HER2 protein expression on some cases was determined by immunohistochemistry. Molecular subtypes definitions were as follows: Luminal A (ER+, PR+/-, HER2-), luminal B ( ER+, PR+/-, HER2+), Triple negative (ER-, PR-, HER2-), HER2+( ER-, PR-, HER+), they were correlated with some clinical characteristics: median age, histological type, SBR grade and pathological axillary lymph node status.

Results: The mean and median age of the 829 patients were 50.66 and 49 years respectively. 62% of the patients had positive lymph nodes and 11% had distant metastasis at diagnosis. Metastasis free survival at 5 years was 70%. Proportions of molecular subtypes were as follows: 41.86% luminal A, 29.58% triple negative breast cancer, 15.09% luminal B and 13.46% HER2+. A significant difference was noted with axillary lymph node (P=0.038), Invasive ductal carcinoma was predominant among all molecular subtypes, Luminal A patients represents the highest proportion of axillary lumph node, and all women represent to diagnosis at the intermediate or late stages of breast cancer.

Conclusions: The distribution of molecular subtypes of breast cancer differs when comparing to other countries, Luminal A subtype is the commonest subtype among West Algerian patients. Women were young and had an aggressive breast cancer profile this might be due to high prevalence of triple negative breast cancer subtype. This study will lead to enhance the care of patients.