Types of breast cancer

Common types of breast cancer

The most common types of breast cancer begin either in your breast's milk ducts (ductal carcinoma) or in the milk-producing glands (lobular carcinoma). The point of origin is determined by the appearance of the cancer cells under a microscope.

In situ breast cancer
In situ (noninvasive) breast cancer refers to cancer in which the cells have remained within their place of origin — they haven't spread to breast tissue around the duct or lobule. The most common type of noninvasive breast cancer is ductal carcinoma in situ (DCIS), which is confined to the lining of the milk ducts. The abnormal cells haven't spread through the duct walls into surrounding breast tissue. With appropriate treatment, DCIS has an excellent prognosis.

Invasive breast cancer
Invasive (infiltrating) breast cancers spread outside the membrane that lines a duct or lobule, invading the surrounding tissues. The cancer cells can then travel to other parts of your body, such as the lymph nodes.

* Invasive ductal carcinoma (IDC). IDC accounts for about 70 percent of all breast cancers. The cancer cells form in the lining of your milk duct, then break through the ductal wall and invade nearby breast tissue. The cancer cells may remain localized — staying near the site of origin — or spread (metastasize) throughout your body, carried by your bloodstream or lymphatic system.
* Invasive lobular carcinoma (ILC). Although less common than IDC, this type of breast cancer invades in a similar way, starting in the milk-producing lobules and then breaking into the surrounding breast tissue. ILC can also spread to more distant parts of your body. With this type of cancer, you typically won't feel a distinct, firm lump but rather a fullness or area of thickening.



Less common types of breast cancer

Not all types of breast cancer begin in a duct or lobule. Less common types of breast cancer may arise from the breast's supporting tissue, including the fibrous connective tissue, blood vessels and lymphatic system. In addition, some tumors don't actually begin in the breast but represent a different type of cancer that has spread (metastasized) from another part of the body, such as the lymphatic system (non-Hodgkin's lymphoma), skin (melanoma), colon or lungs. These are not called breast cancer but are referred to as cancer from where it started, now metastatic to the breast.

Unusual types of breast cancer include inflammatory breast cancer, phyllodes tumor, angiosarcoma, osteosarcoma, metaplastic breast cancer, adenoid cystic carcinoma and Paget's disease of the breast. There are also rare subtypes of invasive ductal carcinoma — tubular, mucinous, medullary and papillary.



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