Molecular Profiling of Breast Carcinoma in Almadinah, KSA: Immunophenotyping and Clinicopathological Correlation.

Purpose: To subtype breast cancer (BC) in Saudi women according to the recent molecular classification and to correlate these subtypes with available clinicopathological parameters.

Materials And Methods: Estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor (Her2/neu) immunostaining was semi-quantitatively assessed to define molecular subtypes of luminal A and B, HER-2 and triple negative (basal- like) in BC paraffin embedded sections from 115 Saudi female patients diagnosed between 2005 to 2015 at the Department of Pathology, King Fahd Hospital, Almadinah, Saudi Arabia.

Results: The most common subtypes were luminal A (47%), followed by luminal B (27.8%) and basal like subtypes (18.3%), whereas HER-2 was the least common subtype (6.9%). Luminal A was predominantly found in the old age group, with low tumor grade (p< 0.001) and small tumor size, whereas HER-2 and basal-like subtypes were significantly associated with young age, high tumor grade, lymph node metastasis and lymphovascular invasion (p< 0.03, 0.004, 0.05 and 0.04 respectively). All subtypes showed advanced clinical stage at the time of presentation.

Conclusions: Molecular subtypes of Saudi BC patients in Almadinah region are consistent with most of the worldwide subtyping. The biological behaviour of each molecular subtype could be expected based on its characteristic clinicopathological features. Along with other prognostic indicators, molecular subtyping would be helpful in predicting prognosis and management of our BC patients. We recommend screening and early diagnosis of BC in our population.