The breast is comprised of organs called lobules that can make drain and thin tubes called conduits that convey the drain from the lobules to the nipple. Breast tissue likewise contains lymph nodes, fat and connective tissue, arteries and veins. Breast cancer is a cancer that starts in the cells of the lobules or in the different tissues of the breast. The cancer may be of various types. Breast cancer that has spread from where it started in the pipes or lobules to encompassing tissue is called intrusive breast cancer. In incendiary breast cancer, the breast looks red and swollen and feels warm on the grounds that the tumor cells hinder the lymph vessels in the skin.

Mastectomy is the removal of the whole breast. There are five different types of mastectomy: "simple" or "total" mastectomy, modified radical mastectomy, radical mastectomy, partial mastectomy, and subcutaneous (nipple-sparing) mastectomy.

After surgery:

Radiation therapy uses high-powered beams of energy, such as X-rays and protons, to kill cancer cells. Radiation therapy is typically done using a large machine that aims the energy beams at your body (external beam radiation). But radiation can also be done by placing radioactive material inside your body (brachytherapy). External beam radiation of the whole breast is commonly used after a lumpectomy. Breast brachytherapy may be an option after a lumpectomy if you have a low risk of cancer recurrence.

Chemotherapy uses drugs to destroy fast-growing cells, such as cancer cells. If your cancer has a high risk of returning or spreading to another part of your body, your doctor may recommend chemotherapy after surgery to decrease the chance that cancer will recur. Chemotherapy is sometimes given before surgery in women with larger breast tumours. The goal is to shrink a tumour to a size that makes it easier to remove with surgery.