Types of breast cancer

In addition to the visible parts of the breast such as nipple and areola, the breast is composed of acini, lobules, ducts and lobes. Acini are alveoli lined of round clusters of epithelial cells; their role is to secrete the milk. Grouping together, the acini form the lobules. These "lobes" in turn lead to milk ducts, small canals through which milk is supplied to the openings of the nipple (lactation).

Pathologically, there exist different types of breast cancer and each one has a characteristic and evolution of its own. The therapy is also based on the type of breast cancer. In general, breast cancer is divided into two broad categories; and each of these categories includes sub-types: non-invasive or in situ cancer, which only affects the borders of a duct or lobule; and invasive or infiltrating cancer, which invades the fatty tissue of the breast. Although it can be, invasive breast cancer does not automatically mean metastatic breast cancer.

Noninvasive or In Situ Breast Cancer

In a non-invasive breast cancer, cancer cells locate only inside the breast ducts or lobules. Depending on its characteristic (aggressive or not), carcinoma in situ can be considered as a precancerous tumor. Non-invasive breast cancer includes two sub categories.

Intra-ductal cancer or ductal carcinoma in situ (DCIS) – a breast cancer is said DCIS if the cancer cells develop within a milk duct of your breast. Ductal carcinoma in situ is the most common form of non-invasive breast cancer, representing approximately 80% of cases. The diagnosis of ductal carcinoma in situ requires sensitive tests such as mammography for detection. In almost all cases, treatment leads to complete recovery. However, if left untreated, the cancer can become "invasive", and spread outside the lactiferous ducts.
Lobular carcinoma in situ (LCIS), Intralobular Cancer or Lobular Neoplasia - generally, breast cancer is considered as lobular carcinoma in situ if the cancer cells locate solely in the lobules. LCIS is responsible for about 10% of non-invasive breast cancer. This type of breast cancer is often diagnosed before menopause, and often discovered by hazard during diagnosis performed for other medical problems. Lobular carcinoma in situ is often considered a pre-cancer of the breast instead of a real breast cancer; however, having it increases your chance of developing invasive breast cancer later in life. Therefore, it is important to treat it as earlier as possible.

Invasive cancer

Invasive Ductal Carcinoma (IDC) or Infiltrating Ductal Carcinoma – this form of malignant tumor usually starts in the milk ducts, but makes its way out of the duct tubes and spreads to neighboring breast tissue. Without treatment, these cancer cells will continue to develop into a malignant mass in the breast. In complicated cases, these malignant cells can also spread into the lymph nodes and other remote sites of the body to form other malignancies; this type of cancer is called metastatic breast cancer.

Depending on the location of the tumor, the nipple can retract or sometimes produce discharge. In some women, the breast skin may fold and retract. Invasive ductal carcinoma is the most common type of breast cancer, representing approximately 70% of cases.

Infiltrating/Invasive Lobular Cancer or InvasiveLobular Carcinoma (ILC) - in this form of breast cancer, cancer cells are developing in the lobules and then pass through the wall of the lobules to spread into surrounding tissues. Invasive lobular cancer is not characterized by inflammation and is less tangible and less visible on mammography. Usually, the cancer is manifested by a vague thickening of the breast tissue, making it often diagnosed late when the tumor reaches a more or less large size.

Lobular carcinoma (ILC) can develop in two or more sites within the same breast or in both breasts. In addition, it is often accompanied by metastases to lymph nodes, the gastrointestinal tract and ovaries. Therapeutic decision of your doctor depends on your age, health status, and biological characteristics of the tumor. Lobular cancers tend to be less sensitive to chemotherapy. Lobular carcinoma represents the second most common form of breast cancer; it is account for 5-15% of cases.

Medullary Carcinoma - medullary carcinoma of the breast is a rare malignant breast tumor, representing less than 5% of all breast cancers. It is characterized by a large solid lesion well defined in the breast. The tumor is often diagnosed in women who are in their late 40s and early 50s, especially women who are genetically at risk of cancer because of mutations in the BRCA1 (a human tumor suppressor gene which produces a protein called breast cancer type 1 susceptibility protein). Prognosis is often better than that of invasive or infiltrating ductal carcinoma (IDC); the tumor does not grow quickly or spread into lymph nodes outside the breast.

Medullary carcinoma has a soft and uniform consistency, resembles the medulla, the lower half of the brainstem. Medullary carcinoma has a predominance of left breast (about 55%) and upper quadrants (more than 65%).

Cystosarcomas Phyllodes - in this rare form of breast cancer, the cancer cells invade the stroma, the connective tissue cells of the breast. This is a solid tumor that can reach a large volume. Even after a successful treatment, the cancer may recur locally in approximately 20-35% of cases. Metastases occur in 15% of patients. Although rare, lymph node metastases can occur; in this case, the cancer cells spread through the bloodstream. In the absence of metastasis, the prognosis is often good.

Mucinous(Colloid) Carcinoma- this type of cancer is responsible for 2-4% of breast cancer cases. It grows mainly in postmenopausal women. Although slow growing, the tumor can grow to become a large tumor. In general, mucinous carcinoma has a better prognosis than infiltrating ductal carcinoma (IDC).

Paget's disease of the breast (Paget's disease of the nipple) – this is a rare tumor that is characterized by a small wound in the form of eczema in the nipple that does not heal. There may be redness, nipple discharge and crust. In 50% -75% of cases, there is a mass which is palpable. Paget's disease of the breast is a rare malignant tumor occurs mainly in women over 40 years, accounting for 1% -4% of breast cancers.

Because the lesion has a similarity with eczema, Paget's disease of the nipple is often diagnosed late. Its treatment of choice is surgery: total mastectomy or modified radical mastectomy.

Paget's disease can also occur also in areas of the vulva and around the anus. However, the disease should not be confused with Paget’s disease of bone; they are two different medical condition.

Inflammatory Breast Cancer (IBC) - this type of breast cancer is relatively rare but fast-growing and aggressive. It is mainly characterized by redness and swelling associated with warmth in the breast. The skin may also appear pink, reddish purple or bruised. The skin of the breast can take a texture similar to skin of an orange. It may also be a change in the appearance of the nipple and pain in the breast. Inflammatory breast cancer is account for about 3% of cases of breast cancer.

Although the inflammatory breast cancer tends to grow rapidly, the cancer can be difficult to diagnose at the beginning because its symptoms are similar to those of a breast infection. In addition, it is difficult to treat inflammatory breast cancer; at diagnosis, the cancer has often already spread into lymph nodes. In contrast to some types of breast cancer, the prognosis of inflammatory breast cancer is often bad.

Other less common carcinoma:

There are other less common carcinomas; their frequency combined is less than 1% of breast cancer cases. Some of them include: