There are many different types of breast cancer, and understanding exactly what factors make up a specific type of breast cancer is vital to its treatment. Depending on the type of breast cancer it is – the symptoms, diagnosis and the treatment are completely varied. Breast cancer is defined by the type of cancerous cells in the breast.
The most common types are known as carcinomas, which form tumors in the epithelial cells surrounding the organs and tissue. More specifically, most breast cancers are a form of carcinomas called adenocarcinoma. Adenocarcinoma starts in the glandular tissues that make up the milk ducts and milk-producing glands (lobule).
Ductal carcinoma in situ (DCIS): DCIS is also known as intraductal carcinoma or stage 0 breast cancer. It is considered a non-invasive or pre-invasive breast cancer, which means that the milk duct contains cancer cells that haven’t spread into the breast tissue. Because the cancer has not yet spread into the surrounding tissue, it cannot spread into the rest of the body and is therefore very treatable.
Lobular carcinoma in situ (LCIS): LCIS or lobular neoplasia is not actually considered a cancer; rather it is a concerning change in the breasts. It is diagnosed when doctors find cells that look like cancer cells in the lobules or glands that produce milk. Unlike DCIS, it typically does not spread any further, even if left untreated. However, women who have LCIS are 7 to 12 times more likely to develop an invasive cancer.
Invasive (infiltrating) ductal carcinoma (IDC): IDC is the most common type of breast cancer, accounting for approximately 8 out of 10 cases of invasive breast cancers in women and 9 out of 10 cases for men. The cancer starts in the cells around the milk duct, but unlike the in situ cancer, it breaks through the walls and spreads into the surrounding breast tissue. Then, through the lymph system, the cancer spreads through other parts of the body. It is usually diagnosed by a hard, misshapen lump in the breast and an inverted nipple.
Invasive lobular carcinoma (ILC): ILC starts in the glands that produce milk (lobules), passes the barrier of the lobule into the breast tissue, through the lymph nodes and ultimately spreads to other parts of the body. As opposed to IDC, ILC is less common, accounting for 1 in 10 cases of invasive breast cancers. In addition, ILC is more likely to be found in both breasts than with other types of breast cancers. ILC is much more difficult to detect because it usually cannot be found in a mammogram and does not form a detectable lump. Instead, doctors most likely will have to extract breast cells using a needle.