Distribution and Clinicopathological Characteristics of Breast Cancer Molecular Subtypes in Turkish Women

Purpose: Today, racial/ethnic differences in the incidence and prognosis of breast cancer (BC) are a well-known fact. This study aimed to examine the distribution of BC molecular subtypes in Turkish women and their relationship with other prognostic clinicopathological variables. Methods: In our surgical oncology clinic, the database of 480 BC cases was retrospectively scanned between January 2008 and December 2020, and the demographic and histopathological results of the patients were recorded. Patients were classified into five main molecular subtypes. Survival curves were estimated using the Kaplan – Meier method. The relationship between categorical variables was analyzed using the chisquare test. Results: The mean age of the patients at the time of diagnosis was 54.5 years, 46.3% were premenopausal, the mean tumor size was 28.7 mm, most of them were T1 (54%), ER, PR, HER-2 positivity rates were 79.6%, 73.1%, 38.3%, respectively and Ki-67 index average was 31.6. The most common molecular subtype was Luminal B Her2B-(33.5%). During a mean follow-up period of 56.9 months, 5 and 10-year overall survival (OS) rates were 89.5%, 79.6%, respectively, and disease-free survival (DFS) rates were 86.9%, 70.5%, respectively. The recurrence rate was 12.3%, distribution by molecular subtypes was significant (p=0.02). Luminal A and Luminal B/Her2- were in relation with Lobular Carcinoma (p=0.005), low histological grade (p=0.00), small tumor size (p=0.00), absence of lymphovascular invasion (LVI) (p=0.00), breast conserving surgery (p=0.022), presence of menopause (p =0.005) and local disease (p =0.013). Conclusions: This study showed that there are differences in molecular subtyping for symptomatic BC in Turkish women.