FREQUENCY OF DIFFERENT MOLECULAR SUBTYPES OF BREAST CANCER IN PAKISTANI POPULATION: A SINGLE CENTER STUDY
Objective: Breast cancer is a malignant disease caused by an uncontrolled growth of cancerous cells in the breast. It is a heterogeneous disease, consists of several molecular subtypes with different biological behavior, epidemiological risk factors, natural histories, response against local and systemic treatment and also prognosis. The objective of the study was to determine the frequency of different molecular subtypes of breast cancer at our center.
Materials and Methods: A descriptive cross-sectional study was performed on 214 cases at Chughtai Institute of Pathology from 1st September 2018 to 30th April 2019. The clinical parameters like age and provisional diagnosis were recorded. The immunohistochemical (IHC) analysis was performed on serial sections using immune-enzymatic soluble complex method. The antibodies used were Ki67, ER, PR and HER2 polyclonal antibodies from DAKO. Scoring of ER and PR IHC were done according to Allred Score for ER and PR evaluation in breast cancer protocol template of College of American Pathologists (CAP). Similarly, HER2 scoring was also done according to reporting guidelines of HER2 testing by IHC given in breast cancer protocol template of CAP.
Results: There were 55.97±16.40 years of age and 3.91±1.78 cm of the tumor size. 38.8% has luminal A, 30.8% had triple negative, 15.5% had luminal B and 14.9% had HER2 enriched molecular subtypes. According tumor sites, 87 had UOQ site ,51 had central site, 50 had LIQ site, 20 had LOQ site, and 6 had UIQ site. The histologic grades showed that tumors with Grade II morphology were 51.9%, Grade III were 42.9% and Grade I were 5.2%. There were 104 (48.6%) patients with right laterality and 110 (51.4%) patients with left laterality.
Conclusion: Luminal A molecular subtype of breast cancer was found as the most common subtype in this study.
Key Words: Frequency, Molecular subtypes, Breast cancer, Immunohistochemistry.