There are many different types of cancer, but most start in the same way: by DNA being damaged by cancerous agents, causing the cells to grow out of control. The cancer is always named after the tissue in which it originated. If a cancer originated in the breast it will always be referred to as breast cancer, even if it spreads to other specific organs or parts of the body.

Specific types of cancer are treated in different ways depending on their tissue of origin, but sometimes it is not obvious where a cancer first developed. If this is the case it can be very difficult to choose the most effective treatment. Some types of cancer have a hereditary cause. In hereditary cancers, a cancer-predisposing mutation in the DNA of one or both of the parents is passed on to the offspring, putting the offspring at risk for developing cancer. For example, if there is a clear history of breast cancer in your family, women in the family chain may have a higher risk of getting breast cancer due to a genetic predisposition, which can be analyzed using molecular diagnostic tools.