Metaplastic Carcinoma Resources page is for informational purposes only. Please remember to always discuss all medical issues with your medical team.
Metaplastic Breast Cancer (MpBC), also called metaplastic carcinoma of the breast, is an extremely rare type of breast cancer. Currently it is not well understood,(1) with no disease specific treatment protocol. Metaplastic breast cancer describes a cancer that is a mixture of different cell types. It is very different from the typical ductal or lobular breast cancer. In a study by Wargotz & Norris five sub-types of Squamous cell,(2) Spindle cell,(3) Matrix-producing,(4) Carcinosarcoma(5) and Osteoclastic giant cell.(6) The final determination on your tumors size, type and stage is done by a pathologist. After the biopsy or surgery, the tissue removed is sent to a pathologist who performs a number of tests and determines the type and sub-type of the tumor.
Metaplastic breast cancer presents differently than other more common forms of breast cancer. For one thing because of the aggressive nature of the disease on average MpBC tumors are usually graded higher and are larger at diagnosis. Often the tumors are triple negative (not hormone receptor positive or hormone receptive) or have very little reactivity to estrogen, progesterone and HER2. MpBC tumors can be difficult to detect using mammograms and are sometimes mistaken for cysts. Metaplastic breast cancer tumors can be painful, something that is uncommon with Invasive Ductal Carcinoma (IDC). Metaplastic breast cancer has a lower rate of lymph node metastasis relative to invasive ductal or lobular carcinoma. MpBC is known to recur more often and in a shorter time frame than IDC or ILC.
Metaplastic carcinoma is a heterogeneous disease which means that it has many subtypes but is defined primarily by the tumor composition. Most breast cancers cells arise from the glandular (epithelial) tissue but metaplastic breast cancer can also be mixed with other types of cells not normally found in the breast, like skin, muscle or bone cells (mesenchymal). Metaplastic means “to change form.” The reason why these cells appear is still under debate. There are two theories, the most recent thinking is that metaplastic tumors are formed when stem cells develop the “wrong” kind of cell for the breast. The other theory is that the normal epithelial (glandular) cells somehow transition into mesenchymal (bone, muscle or skin) cells but how or why this happens is not known. This is referred to as EMT (epithelial to mesenchymal transition). You may run across references to EMT while researching metaplastic cancers. Regardless of which theory turns out to be the correct one, metaplastic tumors are always a mix of epithelial cells and mesenchymal cells.
Due to the rarity of this cancer, and the relatively small group of individuals affected by the disease, medical research has not been as aggressive and successful in pursuing a cure, or even an agreed to treatment protocol.