Descriptive analysis of molecular subtypes in Tunisian breast cancer

Abstract

Aim: The objective is to report the correlation between pathology and molecular subtype classifications of breast cancer in Tunisian women.

Methods: This retrospective study concerned data of 966 breast cancer cases collected from 2007 to 2009 at Salah Azaiz Institute of Tunis. These cases were classified by an immunohistochemistry test for estrogen and progesterone receptors and human epidermal growth factor receptor 2 (HER2) status in the four molecular subtypes, namely luminal A, luminal B, HER2+ and triple negative. The molecular classifications were correlated with the clinicopathological characteristics of the tumors.

Results: Luminal A (50.7% of cases) was the most common subtype, with triple negative subtype 22.5%, luminal B 13.4% and HER2+ 13.4%. Triple negative and HER2+ subtypes were significantly associated with large tumor size (>5 cm, P < 0.001), younger age (<40 years, P < 0.03) and high grade (P < 0.001). Conversely, there was no correlation with the lymph node status.

Conclusion: Our data demonstrated that the luminal A subtype, associated with a favorable prognosis, was the most frequent subtype in the Tunisian population; however the triple negative subtype occurred at a high incidence in Tunisia compared to Western countries. The molecular subtypes are correlated to the tumor size, histological grade and patient's age.

Keywords: breast cancer; hormone receptor; human epidermal growth factor receptor 2; immunohistochemistry; molecular subtype.