Description of the disease
Risk factors for the disease
Lifestyle choices you can make in your life to decrease your modifiable risk factors for this disease
Breast cancer is a type of cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas, while those originating from lobules are known as lobular carcinomas. Breast cancer occurs in humans and other mammals.
The primary risk factors for breast cancer are female sex and older age. Other potential risk factors include: genetics, lack of childbearing or lack of breastfeeding, higher levels of certain hormones, certain dietary patterns, and obesity. Recent studies have indicated that exposure to light pollution is a risk factor for the development of breast cancer.
Smoking tobacco appears to increase the risk of breast cancer, with the greater the amount smoked and the earlier in life that smoking began, the higher the risk. In those who are long-term smokers, the risk is increased 35% to 50%. A lack of physical activity has been linked to ~10% of cases. The association between breast feeding and breast cancer has not been clearly determined; some studies have found support for an association while others have not. In the 1980s, the abortion–breast cancer hypothesis posited that induced abortion increased the risk of developing breast cancer. This hypothesis was the subject of extensive scientific inquiry, which concluded that neither miscarriages nor abortions are associated with a heightened risk for breast cancer. There may be an association between use of oral contraceptives and the development of premenopausal breast cancer, but whether oral contraceptives use may actually cause premenopausal breast cancer is a matter of debate. If there is indeed a link, the absolute effect is small. In those with mutations in the breast cancer susceptibility genes BRCA1 or BRCA2, or who have a family history of breast cancer, use of modern oral contraceptives does not appear to affect the subsequent[clarification needed (subsequent to what?)] risk of breast cancer. There is a relationship between diet and breast cancer, including an increased risk with a high fat diet, alcohol intake, and obesity. Dietary iodine deficiency may also play a role. Other risk factors include radiation, and shift-work. A number of chemicals have also been linked including: polychlorinated biphenyls, polycyclic aromatic hydrocarbons, organic solvents and a number of pesticides. Although the radiation from mammography is a low dose, it is estimated that yearly screening from 40 to 80 years of age will cause approximately 225 cases of fatal breast cancer per million women screened.