Histopathological and Molecular Characteristics of Malignant Breast Tumors in the Kurdish Population During 2019 - 2021

Background: Breast cancer, the most prevalent cancer in women and the second leading cause of cancer-related deaths worldwide, is a complex and heterogeneous disease characterized by multiple tumor types with distinct tissue patterns, biological characteristics, and clinical behaviors. Given the critical role of histopathological and molecular characteristics in the treatment and management of breast cancer. Objectives: This study was undertaken to investigate the histopathological characteristics of malignant breast masses in the city of Sanandaj from 2019 to 2021. Methods: In this descriptive-analytical study, out of 1,631 pathology reports from breast tissue samples collected in Sanandaj, a city in northwest Iran, between 2019 and 2021, 597 (36%) malignant cases were examined for their pathological type and molecular characteristics. Data analysis was performed using SPSS 26 software, employing chi-square and Fisher's exact tests. Results: The mean age of the patients at diagnosis was 49.7 ± 11.9 years. The most prevalent molecular subtype was luminal A (56.4%), followed by triple-negative (16.7%), human epidermal growth factor receptor 2 (HER2)-positive/enriched (14.1%), and luminal B (14%). Invasive ductal carcinoma was the predominant histological type, accounting for 82.7% of cases, followed by lobular invasive carcinoma (8.2%). Papillary carcinoma accounted for 5.9% of cases, metaplastic carcinoma for 1.8%, and mucinous carcinoma for 1.3%. Higher grades at the time of diagnosis were associated with the metaplastic subtype (P < 0.001). The only biomarker that showed a significant association with pathological types of breast cancer was Ki-67. The percentage of cases positive for Ki-67 was higher in three types of breast cancer: Infiltrating ductal carcinoma, metaplastic, and papillary (intraductal) carcinoma, compared to the other types (P < 0.001). Conclusions: According to our data, infiltrating ductal and lobular carcinoma are the most prevalent pathological types, and luminal A is the most common molecular subtype among Kurdish women in Iran. It is recommended that future studies examine patient survival based on the pathological and molecular types of tumors, including the evaluation of additional biomarkers. Furthermore, comparing these results with those from other ethnic groups could provide valuable insights into the impact of ethnicity on breast cancer characteristics and outcomes.