Predominance of the Luminal B molecular subtype in a group of women with infiltrating breast cancer from the coffee region of Colombia: Analysis by immunohistochemistry

Abstract

Breast cancer is the most common cancer in women and constitutes a public health problem due to its high rates of morbidity and mortality. Diagnosis is made through routine histopathology studies that are complemented by expression studies of hormone receptors (Estrogen and Progesterone Receptors), human epidermal growth factor 2 (HER2) and cell proliferation index (Ki67) for their subtyping into molecular groups (Luminal A, Luminal B, Her2 and triple negative), which have different prognostic and therapeutic implications. Globally, a high prevalence of the Luminal A subtype has been reported, predominantly in North America, Europe, and some Latin American countries; however, the reports in the Colombian population are heterogeneous. The objective of this research is to establish an incidence profile of these molecular subtypes in a population of the coffee region in Colombia. In retrospect, samples of 377 patients with a diagnosis of infiltrating breast cancer were analyzed, between the years 2015 and 2018. The histological diagnoses included: NOS infiltrating ductal carcinomas (339 cases; 89.9 %), infiltrating lobular (23 cases; 6.1%), infiltrating mucinous (6 cases; 1.5%), infiltrating papillary (1 case; 0.2%) and mixed patterns: ductal - lobular (3 cases; 0.7%) and ductal with mucinous component (5 cases; 1.3%), of which 56.2% (212 cases) correspond to luminal B, 22.2% (84 cases) to Luminal A, 14.8% (56 cases) to triple negative and 6.6% (25 cases) to HER2. These findings contrast with the prevalence reported worldwide. Therefore, in the population of the Colombian coffee region, this predominance of the luminal pattern B should be considered when establishing prognosis and treatment from medical staff.