Predominance of the luminal B molecular subtype in a group of women with infiltrating breast ductal carcinoma in the Colombian coffee region: Analysis by immunohistochemistry.

Abstract

e12571 Background: 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 phenotypic 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. Methods: Samples of 377 patients with a diagnosis of infiltrating breast cancer were collected retrospectively between 2015 and 2018. Inclusion criteria included: 1) Availability of personal data (year of diagnosis and age) 2) Infiltrating breast carcinoma. 3) Diagnosis between 2015 and 2018. 4) Study of complete immunohistochemistry and/or in situ hybridization (ISH) markers. Results: The histological subtypes 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 mucinous - ductal (5 cases; 1.3 %), of whom 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. Conclusions: These findings contrast with the prevalence reported worldwide. Therefore, in the population of the Colombian coffee region, this predominance of the molecular subtype luminal B should be considered when establishing prognosis and treatment plan by the medical staff.