Causes breast cancer :

In most cases, it isn't clear what causes normal breast cells to become cancerous only 5 percent to 10 percent of breast cancers are inherited. Families that do have genetic defects in one of two genes, breast cancer gene 1 (BRCA1) or breast cancer gene 2 (BRCA2), have a much greater risk of developing both breast and ovarian cancer. Other inherited mutations including the ataxia-telangiectasia mutation gene, the cell-cycle checkpoint kinase 2 (CHEK-2) gene and the p53 tumor suppressor gene also make it more likely that you'll develop breast cancer. If one of these genes is present in your family, you have a 50 percent chance of having the gene. The new tumor has the same kind of abnormal cells and the same name as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer. For that reason, it is treated as breast cancer, not bone cancer. Doctors call the new tumor or metastatic disease. Breast implants, using antiperspirants, and wearing underwire bras do not raise your risk for breast cancer. There is no evidence of a direct link between breast cancer and induced abortion or pesticides.

1. Age and gender , Your risk of developing breast cancer increases as you get older. The majority of advanced breast cancer cases are found in women over age 50. Women are 100 times more likely to get breast cancer then men.
2. Family history of breast cancer, You may also have a higher risk for breast cancer if you have a close relative has had breast, uterine, ovarian, or colon cancer. About 20-30% of women with breast cancer have a family history of the disease.
3. Genes, Some people have genes that make them more prone to developing breast cancer. The most common gene defects are found in the BRCA1 and BRCA2 genes. These genes normally produce proteins that protect you from cancer. But if a parent passes you a defective gene, you have an increased risk for breast cancer. Other genetic defects have been linked to breast cancer, including those found in the ATM gene, the CHEK-2 gene, and the p53 tumor suppressor gene, but these are very rare.
4. Menstrual cycle, Women who get their periods early (before age 12) or went through menopause late (after age 55) have an increased risk for breast cancer.
5. Other risk factors include:
6. Alcohol use, Drinking more than 1-2 glasses of alcohol a day may increase your risk for breast cancer.
7. Childbirth,Women who have never had children or who had them only after age 30 have an increased risk for breast cancer. Being pregnant more than once or becoming pregnant at an early age reduces your risk of breast cancer.
8. DES, Women who took diethylstilbestrol (DES) to prevent miscarriage may have an increased risk of breast cancer after age 40. This drug was given to the women in the 1940s-1960s.
9. Hormone replacement therapy (HRT), You have a higher risk for breast cancer if you have received hormone replacement therapy for several years or more. Many women take HRT to reduce the symptoms of menopause.
10. Obesity, Obesity has been linked to breast cancer, although this link is controversial. The theory is that obese women produce more estrogen, which can fuel the development of breast cancer.
11. Radiation, If you received radiation therapy as a child or young adult to treat cancer of the chest area, you have a significantly higher risk for developing breast cancer. The younger you started such radiation, the higher your risk especially if the radiation was given when a female was developing breasts.