The breast is an organ composed mainly of fat, glands and milk ducts (also called lactiferous ducts, galactophorous ducts, mammary ducts, or mamillary ducts). During periods of lactation, the glands produce milk, which is transported to the nipple by the ducts. In a healthy breast, cells group together to form tissues. Each tissue works together synchronously and harmoniously to perform a similar function. The breast tissue is influenced by hormones estrogen and progesterone, two hormones produced by women in variable amounts throughout their lives: puberty, pregnancy, lactation, etc.
Breast cancer occurs when a group of normal cells begin to transform and divide in an uncontrolled manner to become malignant. If your immune system is healthy enough, these tumor cells will be destroyed. Otherwise, these diseased cells continue to multiply to form a malignant tumor (cancer), first limited within the breast; in fact, these cancer cells can remain in the breast asymptomatically for months or years. With time, however, they travel through the lymphatic system or bloodstream to invade other organs distant from the breast to form new tumors called metastases.
Despite advances in medical science, the exact causes of breast cancer are still not well known. However, many conditions are suspected in the development of the disease. For example, immediate family history of breast cancer represents 5-10% risk factor of the disease. In addition, excess weight, diet rich in animal fats, lack of pregnancy, late first pregnancy, early onset of menstruation, late menopause, certain forms of mastopathy (any non malignant disease or pain of the mammary gland), and malignant tumor of the large bowel, uterine or ovaries also seem to contribute in the development of breast cancer.