الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
 |  | from | 239 |  |  |
| | | from | 239 | | |
Abstract
Breast cancer is the most common cause of cancer death among women. The worldwide incidence of this pathological condition is reported to affect 1.2 million individuals each year (1). Incidence of breast cancer is higher in more developed countries in comparison to less developed countries. In the United States of America, more than 200,000 women are diagnosed with breast cancer every year, which accounts for the 30.4% of all newly diagnosed neoplasm in that country (2). In Egypt, breast cancer is the most common cancer among women, representing 18.9% of total cancer cases (35.1% in women and 2.2% in men) (3).
1.1. Etiology of Breast Cancer
There is no exact cause of breast cancer; however the new advance in molecular and pathological research has identified a lot of predisposing factors. These diverse risks can be assigned to either of two major categories: excessive exposure to estrogens and inheritable factors that lead to deficiency in maintenance of genomic integrity (4). Factors associated with excessive exposure to estrogens include early menarche, late menopause, null-parity, late age of first delivery, postmenopausal obesity with subsequent increase of circulating estrogen, prolonged hormone replacement therapy and hormonal contraceptive (4).While about 10 % of breast cancer cases can be directly linked to the factors that lead to deficiency in maintenance of genomic integrity. These factors include either hereditary or acquired germ-line mutations in several genes including the tumor suppressor gene p53 or one of the breast cancer associated genes-1 and -2 (BRAC-1 and 2) (4, 5). Table 1 represents different oncogenes and tumor suppressor genes involved in breast cancer.