Distribution and clinicopathological features of breast cancer histological subtypes in Latvia

Breast cancer is a heterogenous disease. It consists of several histological subtypes that can be separated by morphology and immunohistochemistry. The aim of our study was to determine the distribution of breast cancer histological and molecular subtypes, and their relationship with clinical and pathological characteristics. A total of 561 patients who underwent breast carcinoma surgical treatment from January 2003 till December 2012 were enrolled in the study. In total, invasive ductal carcinomas not otherwise specified (IDC-NOS) plus invasive ductal carcinomas no special type (IDC-NST) were observed in 430 patients (76.65% of cases), medullar carcinoma in 14 patients (2.45%), other rare ductal carcinoma subtypes in 13 patients (2.31%), lobular carcinoma in 81 patients (14.4%) and tubulolobular carcinoma in 23 patients (4.19%). Ductal carcinoma, lobular and tubulolobular carcinoma had predominantly luminal A and B subtype, whereas medullar carcinoma had HER2-positive and triple-negative (TN) subtype. Tubular, cribriform, mucinous, papillary, and apocrine carcinomas had predominantly luminal A subtype. Significant differences between breast cancer histological subtypes and clinicopathological characteristics were observed. Our study for the first time reported the distribution and characteristics of breast cancer histological subtypes in Latvian women and relationship to clinical and tumour histopathological characteristics.