Prevalence of biological types of breast cancer and their influence on disease staging and therapeutic management - a single-center study.

According to the St. Gallen 2011 consensus, proper qualification of breast cancer patients for treatment requires taking into consideration the division into biological types of neoplasms. The goal of this work was to assess the prevalence of all biological types of breast cancer in the population of Kuyavian-Pomeranian province. We determined the influence of particular types of neoplasms on the degree of disease progression and the choice of therapeutic management. The study was conducted on a group of 2653 patients treated surgically due to malignant breast tumors in the Oncology Centre in Bydgoszcz. In the analyzed clinical material we determined the biological type of cancer as well as other prognostic factors. The most commonly identified types of cancer were luminal B1 type (38.4%) and luminal A type (27.4% of cases), followed by a triple-negative type, luminal B2 type and HER2-positive type (respectively: 11.4%, 10.2%, and 6.9% of patients). Estrogen receptors were present in 81.1% and progesterone receptors in 71.4% of subjects. HER2 overexpression was identified in 17.3% of patients. Routine use of a biology-based division into cancer types influences the choice of anti-cancer treatment. Diagnosis of luminal A type of tumor more commonly than other biological types of cancer coexists with lower clinical and pathological disease staging. It allows for more frequent use of sparing surgical techniques in patients. It also makes systemic neoadjuvant chemotherapy unnecessary in the majority of patients (differences in such cases exhibit statistical significance of p < 0.0001).