Invasive Breast Cancer (Carcinoma)

If you’re told you have an invasive breast cancer, it means that your cancer has spread beyond its original location to invade other parts of the breast and possibly the lymph nodes. Over time, invasive breast cancer may also spread to other, sometimes remote, parts of the body.

Invasive Ductal Carcinoma (IDC)

About 75 percent of women diagnosed with invasive breast cancer each year have IDC, making this the most common form of breast cancer. The disease is “ductal,” which means it starts in the milk ducts, but then grows and invades the surrounding tissue in the breast. As it progresses, it can spread into the lymph nodes. 

IDC is measured in stages, with Stage I being the earliest and Stage III being the most advanced. Surgery is almost always the standard of treatment, whether in the form of a lumpectomy or more extensive procedures. Depending on the size and extent of the cancer, radiation and/or systemic treatments — which can be chemotherapy, hormonal therapy and targeted therapies — may also be used to fight the cancer. 

There are six specific types of Invasive Ductal Carcinoma (IDC), which all begin in the milk ducts and then spread into healthy breast tissue:

Tubular Carcinoma of the Breast

Tubular carcinoma of the breast consists of small tube-shaped tumors called “tubules”. Accounting for up to 27 percent of breast cancers, this is a less aggressive, slow-growing disease that is diagnosed most often in women in their 50s. It usually does not spread beyond the breast, and responds well to treatment. 

Medullary Carcinoma of the Breast

Medullary carcinoma of the breast is a rare form of IDC characterized by soft, fleshy tumors. It is a slow-growing form of breast cancer that doesn’t usually spread outside of the breast. It can occur at any age though it’s more common in women in their late 40s and early 50s. This type of breast cancer responds well to treatment.

Mucinous Carcinoma of the Breast

Mucinous carcinoma of the breast is characterized by a tumor with cancer cells that “float” in pools of mucin, which is an ingredient in mucus. It accounts for only about two to three percent of IDC, and tends to affect post-menopausal women in their 60s and 70s. This less aggressive cancer is less likely to spread to the lymph nodes than other types of breast cancer, and responds well to treatment.

Papillary Carcinoma of the Breast

Papillary carcinoma of the breast, which accounts for less than two percent of IDC cases, is more often seen in older, post-menopausal women. These tumors have small, finger-like projections called papules. This type of cancer is frequently found in a breast that also has ductal carcinoma in situ (DCIS), a breast cancer that is confined to the milk ducts. Papillary carcinoma responds well to treatment.

Cribriform Carcinoma of the Breast

Cribriform carcinoma of the breast has cancer cells that invade the connective tissues of the breast. Cribriform carcinoma is present in about five to six percent of invasive breast cancers. This type of breast cancer responds well to treatment.

Metaplastic Carcinoma

Metaplastic carcinoma is another very rare form of invasive ductal carcinoma, accounting for fewer than one percent of all breast cancers. The word “metaplasia” means the transformation of one cell type to another. With metaplastic carcinoma, the cancer tumor contains two or more types of cancer cells — often both carcinoma and sarcoma. These are very different cancers that usually respond to different treatments. This makes treating this cancer extremely difficult.

Invasive Lobular Carcinoma (ILC)

Accounting for 10 to 15 percent of breast cancers, invasive lobular carcinoma is the second most common type of invasive breast cancer after invasive ductal carcinoma (IDC). 

Invasive lobular carcinoma starts in the breast’s lobules. As it progresses, the cancer breaks through the lobule wall to spread into healthy breast tissue. ILC can spread to the lymph nodes and other parts of the body. While it’s found in women of all ages, ILC more commonly affects those in their early 60s. Treatment options depend on your cancer’s stage and aggressiveness, but most often include surgery, possibly with chemotherapy, radiation and hormone surgery.