Breast cancer originates in your breast tissue. It occurs when breast cells mutate (change) and grow out of control, creating a mass of tissue (tumor). Like other cancers, breast cancer can invade and grow into the tissue surrounding your breast. It can also travel to other parts of your body and form new tumors. When this happens, it’s called metasis.

Starting in your milk ducts of your breast, this cancer breaks through the wall of your duct and spreads to surrounding breast tissue. Making up about 80% of all cases, this is the most common type of breast cancer. Also called Stage 0 breast cancer, ductal carcinoma in situ is considered by some to be precancerous because the cells haven’t spread beyond your milk ducts. This condition is very treatable. However, prompt care is necessary to prevent the cancer from becoming invasive and spreading to other tissues. Lobular carcinoma in situ is a precancerous condition in which there are abnormal cells in the lobules of your breast. It isn't a true cancer, but this marker can indicate the potential for breast cancer later on. So, it’s important for women with lobular carcinoma in situ to have regular clinical breast exams and mammograms. This makes prognosis and treatment difficult.Inflammatory breast cancer. Rare and aggressive, this type of cancer resembles an infection. People with inflammatory breast cancer usually notice redness, swelling, pitting and dimpling of their breast skin. It’s caused by obstructive cancer cells in their skin’s lymph vessels.