Breast Cancer Risk Factors: Having family history of cancer. Menstrual periods beginning before the age of 12. Never having children or having children after age 30. Lack of exercise (being 20 % or more overweight). 90% of breast cancer cases are from genetic abnormalities that happen as a result of aging, which is the process of life. To Reduce Risks: Stop smoking. Exercise regularly. Limiting one's intake of red meat and other sources of animal fat (they may contain stored hormones or pesticides). Lose excess weight and keep the pounds off. Sources: www.cancer.org; www.breastcancer.org