hisBreast cancer Molecular subtypes and their clinicopathological characteristics amongst patients at the Aga Khan University hospital (Nairobi)

Abstract

Introduction Breast cancer is a heterogeneous disease with varying clinical outcomes in histologically similar tumors. Micro arrays gene profiling has identified several breast cancer subtypes which include luminal A, Luminal B, Basal, and Her2 subtype. These subtypes show variable prognosis and response to therapy. Objectives To determine the proportion of the various subtypes at Aga Khan University hospital and describe their clinical and pathological characteristics. Study Design & setting Cross sectional study of all breast cancer specimens received in the pathology department of the Aga Khan university Hospital Nairobi between November 2007 and November 2008. Methods 101 cases of breast cancer were analysed using immunohistochemical surrogates to identify the subtypes. The subtype definition was; Luminal A ( Estrogen receptor(Er) or Progesterone receptor(Pr) positive Her2 negative), Luminal B ( Er, Pr, and Her2 positive), Her 2 sub type (Her2 positive, Er and Pr negative), and basal (Er, Pr,and Her2 negative Cytokeratin 5/6 (Ck5/6) and or Her1 positive). Cases not falling into any category were unclassified. Other clinical pathological characteristics including age, race, menopause status, tumor size, grade and stage were determined in each sub type. Results Luminal A was the most common, 42%, followed by basal, Her2, and luminal B at 23%, 21%, and 4% respectively. 10% of the cases were unclassified. There was no significant difference between the sub types with regard to age, menopause, tumor size and stage. There was a significant difference with regards to grade with the Her2 and basal subtypes having a higher grade. Conclusion The molecular sub types of breast cancer exist in our population. The prevalence of the basal subtype is higher than that seen in studies amongst Caucasians while the prevalence of Luminal A is lower.