What Is Breast Cancer

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06/19/23

https://www.cancer.org/cancer/breast-cancer/about/what-is-breast-cancer.html What Is Breast Cancer? Breast cancer is a type of cancer that starts in the breast. Cancer starts when cells begin to grow out of control. (To learn more about how cancers start and spread, see What Is Cancer?) Breast cancer cells usually form a tumor that can often be seen on an x-ray or felt as a lump. Breast cancer occurs almost entirely in women, but men can get breast cancer, too. It’s important to understand that most breast lumps are benign and not cancer (malignant). Non-cancerous breast tumors are abnormal growths, but they do not spread outside of the breast. They are not life threatening, but some types of benign breast lumps can increase a woman's risk of getting breast cancer. Any breast lump or change needs to be checked by a health care professional to determine if it is benign or malignant (cancer) and if it might affect your future cancer risk. See Non-cancerous Breast Conditions to learn more. Where breast cancer starts Breast cancers can start from different parts of the breast. Most breast cancers begin in the ducts that carry milk to the nipple (ductal cancers) Some start in the glands that make breast milk (lobular cancers) There are also other types of breast cancer that are less common like phyllodes tumor and angiosarcoma A small number of cancers start in other tissues in the breast. These cancers are called sarcomas and lymphomas and are not really thought of as breast cancers. Although many types of breast cancer can cause a lump in the breast, not all do. See Breast Cancer Signs and Symptoms to learn what you should watch for and report to a health care provider. Many breast cancers are also found on screening mammograms, which can detect cancers at an earlier stage, often before they can be felt, and before symptoms develop. Types of breast cancer There are many different types of breast cancer and common ones include ductal carcinoma in situ (DCIS) and invasive carcinoma. Others, like phyllodes tumors and angiosarcoma are less common. Once a biopsy is done, breast cancer cells are tested for proteins called estrogen receptors, progesterone receptors and HER2. The tumor cells are also closely looked at in the lab to find out what grade it is. The specific proteins found and the tumor grade can help decide treatment options. To learn more about specific types of breast cancer and tests done on the breast cancer cells, see Understanding a Breast Cancer Diagnosis. How breast cancer spreads Breast cancer can spread when the cancer cells get into the blood or lymph system and are carried to other parts of the body. The lymph system is a network of lymph (or lymphatic) vessels found throughout the body that connects lymph nodes (small bean-shaped collections of immune system cells). The clear fluid inside the lymph vessels, called lymph, contains tissue by-products and waste material, as well as immune system cells. The lymph vessel