Abstract 3833: Molecular subtypes of breast cancer in Algeria: a population-based study of 3014 women

Abstract Background:Breast cancer is currently the leading cause of cancer morbidity and mortality among Algerian women. Molecular classification of breast cancer is an important factor for prognosis and clinical outcome.To our best knowledge,few studies have been reported on molecular subtypes of female breast cancer in Algeria.The objective of the present study was to evaluate age at diagnosis,distribution,prevalence, and association with menopausal status, histological type and histological grade of molecular subtypes of breast cancer in Algerian women.In addition, we screened for the prevalence of BRCA1 mutations in TNBC patients with and without family history of breast cancer. Methods: We analyzed breast cancers from cancer registries of academic medical oncology service of public hospital of Rouiba, anticancer center of Blida, and anticancer center of Batna.Breast cancers were diagnosed between 2008 and July 2013. ER (oestrogen receptor), PR (progesterone receptor) and HER2 (human epidermal growth factor receptor-2) status were obtained from medical records for 3014 patients.Breast cancer subtypes definitions were as follow:Luminal A (ER+ and/or PR+,HER2-), Luminal B (ER+ and/or PR+,HER2+),TNBC(ER-,PR-,HER2-), HER2+ (ER-,PR-,HER2+). 20 TNBC patients with family history of breast cancer and 33 sporadic TNBC women were screened by using PCR-direct sequencing for 3 common BRCA1 mutations c.83_84delTG, c181T>G and c.798_799delTT detected in previous studies in Algerian population. Results: The median age at diagnosis of 3014 patients with breast cancer was 48.5 years. The prevalence of the Luminal A, TNBC, Luminal B and HER2+ were 50.59%,20.80%, 19.67% and 8.92%,respectively.Luminal A, Luminal B, TNBC and HER2+ subtypes were more prevalent among premenopausal women (29.24%, 13.26%, 12.19% and 4.80%) compared with postmenopausal women (21.74%, 7.31%, 7.89% and 3.87%). Invasive Ductal Carcinoma was the most prevalent histological type in all breast cancer subtypes at any age. Tumors with histological grade 2 were more prevalent in younger patients for the four breast cancer subtypes. High prevalence of histological grade 3 was showed in older patients. The BRCA1 mutation c.83_84delTG was detected in one young TNBC patient with a family history of cancer. Conclusion: For the first time, we report the distribution of molecular subtypes of breast cancer and some clinical characteristics in a large cohort of Algerian women. In our current study, the median age of diagnosis for all breast cancer subtypes was younger than the average age in Europe and America.Interestingly, TNBC subtype was the second most prevalent in our patients,and the prevalence of luminal subtype was lesser than reported in white women with breast cancer in Europe and America. The high prevalence of TNBC reported here could be linked to Sub-Saharan African genetic elements of Algerian population.Screening for BRCA1 mutations in large series of TNBC patients is ongoing. Citation Format: Farid Cherbal, Hadjer Gaceb, Chiraz Mehemmai, Rabah Bakour, Kada Boualga, Wassila Benbrahim, Hassen Mahfouf. Molecular subtypes of breast cancer in Algeria: a population-based study of 3014 women. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3833. doi:10.1158/1538-7445.AM2014-3833