Types of Breast Cancer
When abnormal cells from within the lobules or mammary ducts break out into the surrounding tissue the condition is referred to as invasive breast cancer. However, this term does not necessarily mean that metastases have been found anywhere beyond the breast.
Carcinoma In Situ
Carcinoma in situ is referred to as precancerous condition because it can increase the risk of developing cancer. When abnormal cells grow within the lobules or mammary ducts and there is no sign that the cells have spread into the surrounding tissue or beyond, the condition is called carcinoma in situ. The term in situ means “in place”. There are two main categories of carcinoma in situ: ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS).
Non-invasive cancer is grouped into four subcategories, based on how the cells grow relative to each other within the center of the milk duct:
Solid: There is wall-to-wall cell growth
Cribiform: There are holes between groups of cells, making it look like Swiss cheese.
Papillary: The cells grow in fingerlike projections, toward the inside of the duct.
Comedo: There are areas of "necrosis," which is debris from dead cells; this indicates that a tumor is growing so fast that some tumor cells die because there is insufficient blood supply.
Ductal Carcinoma In Situ
Mammary ducts are hollow to allow fluid to pass through. However, with ductal carcinoma in situ (DCIS) excess cells grow inside the mammary ducts. DCIS is not invasive cancer. It is a precancerous condition that has the potential to develop into breast cancer. DCIS is, however, a risk factor for breast cancer.
Lobular Carcinoma In Situ
The lobules of the breast tissue have open space inside them much like the mammary ducts. Lobular carcinoma in situ (LCIS) is the growth and accumulation of large numbers of abnormal cells within the lobules. LCIS is often referred to as lobular neoplasia in situ. LCIS is not a direct cancer precursor. The abnormal cells found inside the lobules are not likely to mutate into cancer. LCIS is, however, a risk factor for breast cancer.