Connective Tissue Cancers
Breast cancer can begin in the connective tissue that is made up of muscles, fat and blood vessels. Cancer that begins in the connective tissue is called sarcoma. Sarcomas of the breast are rare.
This is a form of cancer that starts from cells that line blood vessels or lymph vessels. It rarely occurs in the breasts. When it does, it usually develops as a complication of previous radiation treatments.
Angiosarcoma can also occur in the arm of women who develop lymphedema as a result of lymph node surgery or radiation therapy to treat breast cancer. These cancers tend to grow and spread quickly. Treatment is generally the same as for other sarcomas.
This rare cancer accounts for less than one percent of all breast tumors. The name "phyllodes," which is taken from the Greek language and means "leaf-like," refers to that fact that the tumor cells grow in a leaf-like pattern. Another name for these tumors is cystosarcoma phyllodes. Phyllodes tumors tend to grow quickly, but they rarely spread outside the breast.
Although most phyllodes tumors are benign (not cancerous), some are malignant (cancerous) and some are borderline (in between noncancerous and cancerous). All three kinds of phyllodes tumors tend to grow quickly. They require surgery to reduce the risk of a phyllodes tumor coming back in the breast (local recurrence).
Phyllodes tumors develop in the stroma (connective tissue) of the breast, in contrast to carcinomas, which develop in the ducts or lobules. They can occur at any age, but they tend to develop when a woman is in her 40s. Benign phyllodes tumors are usually diagnosed at a younger age than malignant phyllodes tumors. Phyllodes tumors are extremely rare in men.
Benign phyllodes tumors are treated by removing the tumor along with a margin of normal breast tissue. A malignant phyllodes tumor is treated by removing it along with a wider margin of normal tissue or by mastectomy. Surgery is often all that is needed. These cancers may not respond as well to the other treatments used for more common breast cancers. When a malignant phyllodes tumor has spread, it may be treated with the chemotherapy given for soft-tissue sarcomas.
Male Breast Cancer
Men do not have the same amount of hormones that stimulate breast tissue to grow into full breasts as women do. However, they occasionally can develop real breast gland tissue because they take certain medicines or have abnormal hormone levels. As a result, they can develop breast cancer.
Because breast cancer in men is rare (less than 1 percent of all breast cancers), few cases are available to study.
Inflammatory Breast Cancer (IBC)
Inflammatory breast cancer is a rare and very aggressive type of breast cancer that causes the lymph vessels in the skin of the breast to become blocked. This type of breast cancer is called "inflammatory" because the breast often looks swollen and red, or "inflamed."
IBC usually starts with the reddening and swelling of the breast instead of a distinct lump or tumor. It also makes the breast feel warm and gives the breast skin a thick, pitted appearance that looks similar to an orange peel.
The affected breast may become larger or firmer, tender or itchy. In its early stages, inflammatory breast cancer is frequently mistaken for an infection in the breast (called mastitis). Often this cancer is first treated as an infection with antibiotics. If the symptoms are caused by cancer, they will not improve, and the skin may be biopsied to look for cancer cells. Because there is no actual lump, it may not show up on a mammogram, which may make it even harder to find it early. This type of breast cancer tends to have a higher chance of spreading and a worse outlook than typical invasive ductal or lobular cancer.
IBC tends to grow and spread quickly, with symptoms worsening within days or even hours. It’s important to recognize symptoms and seek prompt treatment.
IBC accounts for 1 percent to 5 percent of all breast cancer cases in the United States.
Paget's Disease of the Nipple
This is a rare form of breast cancer in which cancer cells collect in or around the nipple. The cancer usually affects the ducts of the nipple first (small milk-carrying tubes). Then, it spreads to the nipple surface and the areola (the dark circle of skin around the nipple). The skin of the nipple and areola often appears crusted, scaly and red, with areas of bleeding or oozing. The woman may notice burning or itching.
The unusual changes in the nipple and areola are often the first indication that breast cancer is present.
Paget's disease of the nipple accounts for less than 5 percent of all breast cancer cases in the United States. Being aware of the symptoms is important, given that more than 97 percent of people with Paget's disease also have ductal carcinoma in situ (DCIS) or, more often, infiltrating ductal carcinoma somewhere else in the breast.
Paget's disease of the nipple is more common in women, but like other forms of breast cancer, it can also affect men. The disease usually develops after age 50. According to the National Cancer Institute, the average age of diagnosis in women is 62, and in men, 69.
Treatment often requires mastectomy. If only DCIS is found (with no invasive cancer) when the breast is removed, the outlook is excellent.
Mixed tumors contain a variety of cell types, such as invasive ductal cancer combined with invasive lobular breast cancer. In this situation, the tumor is treated as if it were an invasive ductal cancer.
Triple-Negative Breast Cancer
This term is used to describe breast cancers (usually invasive ductal carcinomas) whose cells lack estrogen receptors and progesterone receptors, and do not have an excess of the HER2 protein on their surfaces.
Breast cancers with these characteristics tend to occur more often in younger women and in African-American women. Triple-negative breast cancers tend to grow and spread more quickly than most other types of breast cancer.
Because the tumor cells lack these certain receptors, neither hormone therapy nor drugs that target HER2 are effective against these cancers (but chemotherapy can still be useful if needed).
Metaplastic carcinoma is a very rare type of invasive ductal cancer. These tumors include cells that are normally not found in the breast, such as cells that look like skin cells (squamous cells) or cells that make bone. These tumors are treated like invasive ductal cancer.
Adenoid Cystic Carcinoma (Adenocystic Carcinoma)
These cancers have both glandular (adenoid) and cylinder-like (cystic) features when seen under the microscope. They make up less than 1 percent of breast cancers. They rarely spread to the lymph nodes or distant areas and tend to have a very good prognosis.