Most cancers in the breast originate from the cells that line the milk-producing glands and ducts with the cyclical hormonal influence the cells lining the milk glands and the ducts keep replicating normally at a controlled pace, throughout one's reproductive cycle. During this cell division and replication process, things may go wrong and abnormalities in the cells may occur. The body has a method of removing the abnormal cells from the cell division cycle. Sometimes the abnormal cells survive and continue to proliferate in an uncontrolled fashion. These proliferating abnormal cells also need the blood supply and nutrients to grow. As it keeps growing, some of these cells may enter the circulation and have the potential to seed itself and grow in bones, brain, liver, and lung resulting in a compromise of function in vital organs like liver or lungs.

It is still not very clear why this happens in some women more than others. About 5-10 % of breast cancers are thought to occur because of inherited genetic mutation. Reproductive risk factors such as early onset of periods, late menopause, infertility, hormone replacement therapy, late first pregnancy, obesity account for about 25 % of breast cancers. The statistical models that are used to estimate a woman’s risk are often based on western statistics and may not be relevant to our population.