The Etiology Of Breast Cancer - 946 Words

The etiology of breast cancer is unknown. However, hereditary factors are considered the major determinant of individual in risk. Mutation in cancer susceptibility genes such as BRCA1 can be used in the assessment of individuals at risk of developing breast cancer. Breast cancer initiated as a change in single cell. Progression of tumor depends on accumulation of these changes8. Breast cancers are classified by several grading systems. Histopathology grading depends on the histological appearance of tumor. Grade of tumor compares the appearance of the breast cancer cells to the appearance of normal breast tissue with low grade being as well and high grade as poorly differentiated .Classification of Malignant Tumors (TNM) uses three†¦show more content†¦Microarray introduction divided breast cancer to different subtypes with associated with different clinical outcome. Molecular classification leads to further understanding of breast cancer progression. It has provided more wide definition of the disease as a group of malignancies which has the same origin but differ in their biology. DNA microarray clusters breast carcinomas based on the gene expression profiles shifting the treatment to more specific approach guided by certain gene expression. Gene expression profiling divides breast cancer into 3 major subtypes: luminal, human epidermal growth factor receptor 2+ (HER2+), and basal like. Such classification has helped in predicting the treatment and the prognosis of each type11. Hormonal therapy and targeted therapy have replaced chemotherapy for subclasses that overexpress the corresponding receptors. Luminal subtypes (Luminal A, Luminal B) are hormone receptor positive (HR) estrogen receptor (ER)positive and progesterone receptor (PR) positive. They gene expression patterns similar to normal cells that line the breast ducts12-14. Luminal subtypes are known to have better prognosis, high survival rate and low recurrence rate compared to other subtypes .Treatment option of luminal subtypes is based on HR targeting. HER 2 is known for overexpression of human epidermal growth factor receptor 2 (HER2) genes. This subtype of breast