Etiological studies on risk factors for breast cancer have shown that breast cancer is closely related to age, genetic factors, menstrual and marital history, dietary structure, overdiagnosis, and environmental factors. Age, gender and marital history Age is the main risk factor for the development of breast cancer, and the incidence of breast cancer varies by age. The incidence of breast cancer in women is 100 times higher than that in men. Clinically, the incidence is higher in those who have their first menstrual period earlier than 12 years old and those who stop menstruation later than 55 years old; the incidence is significantly higher in those who have their first full-term birth later than 35 years old than those who have their first birth before 20 years old; the incidence is higher in unmarried and infertile women than in married and fertile women. Estrogen is an important tumor-causing hormone, which can affect cell growth and proliferation during the formation of breast cancer. Experimental studies in women’s health organizations have shown that the main reason for the decrease in the incidence of breast cancer is the significant decrease in the use of estrogen therapy after menopause. One of the most common etiological factors of breast cancer is the exposure to exogenous hormones, including oral contraceptives (Ocs; especially in premenopausal cases) and hormone replacement therapy (HRT; especially in postmenopausal cases). Genetic factors The annual risk of breast cancer in carriers of mutated genes is 1.4% to 4%, most typically for mutations in BRCA1 and BRCA2. The lifetime risk of breast cancer for women with mutations in BRCA1 and BRCA2 is 36% to 87% and 45% to 84%, respectively. 4. Obesity and diet Some studies have concluded that high-fat diet and obesity, alcohol intake, and previous radiation are risk factors for breast cancer. Many of the data related to obesity, diet, and alcohol intake are controversial, suggesting only weak or moderate effects, and these factors may not be independent risk factors like age and hormone exposure. 5.Physical activity The risk reduction of breast cancer with continuous physical activity is significant, and vigorous activity may prevent breast cancer better than moderate exercise; therefore, adherence to physical activity that benefits the body extensively may also reduce the risk of breast cancer. 6. Environment The ICRP 2007 Recommendation (ICRP Publication 103) presents new radiation hazard values and tissue weighting factors (Wt), the most notable changes from Publication 60 being the treatment of the breast, gonads and for the remaining tissues. The Wt for the breast changed from 0.05 to 0.12, making it one of the most sensitive tissues to radiation.