What is Breast Cancer?

Breast cancer cells are breast cells that become abnormal over time by dividing uncontrollably. The majority of breast cancers begin in the ducts (85%). 10% percent begin in the lobules of breast tissue It takes about 5-10 years for breast cancer cells to grow into large enough to form a tumor or mass you can feel.

Breast Cancer Facts

In 2015, an estimated 231,840 new cases of invasive breast cancer will be diagnosed among women, as well as an estimated 64,640 additional cases of in situ breast cancer.

In 2015, approximately 39,620 women are expected to die from breast cancer. Only lung cancer accounts for more cancer deaths in women.

In 2015, about 2,350 cases of breast cancer are expected to occur among men, accounting for about 1% of all breast cancers. A man's lifetime risk of breast cancer is 1 in 1,000.

Breast cancer incidence rates are higher in non-Hispanic white women compared to African American women for most age groups. However, African American women have a higher incidence rate before 40 years of age and are more likely to die from breast cancer at every age.

Incidence and death rates for breast cancer are lower among women of other racial and ethnic groups than among non-Hispanic white and African American women.

Types of Breast Cancer​

Invasive ductal carcinoma (IDC), sometimes called infiltrating ductal carcinoma, is the most common type of breast cancer. About 80% of all breast cancers are invasive ductal carcinomas. Invasive means that the cancer has “invaded” or spread to the surrounding breast tissues. Ductal means that the cancer began in the milk ducts, which are the “tubes” that carry milk from the milk-producing lobules to the nipple. Invasive ductal carcinoma” refers to cancer that has broken through the wall of the milk duct and begun to invade the tissues of the breast. Over time, invasive ductal carcinoma can spread to the lymph nodes and possibly to other areas of the body.

Ductal carcinoma in situ (DCIS) is the next common breast cancer. It occurs when abnormal cells grow inside the milk ducts, but stays confined inside the milk duct (has not spread to nearby breast tissue). “In Situ” means in place. The abnormal cells stay inside the milk ducts. You may also hear DCIS called pre-invasive breast cancer.

Invasive lobular carcinoma (ILC) starts in the milk-producing glands (lobules). Like IDC, it can spread (metastasize) to other parts of the body. About 1 in 10 invasive breast cancers is an ILC. Invasive lobular carcinoma may be harder to detect by a mammogram than invasive ductal carcinoma.

Triple-negative breast cancer describes a type of  breast cancer that do not have estrogen or progesterone receptors, nor do they have an excess of Her2 protein on their surfaces. This means that the breast cancer cells have tested negative for hormone epidermal growth factor receptor 2 (HER-2), estrogen receptors (ER), and progesterone receptors (PR).  Anyone can get triple-negative breast cancer. However, researchers have found that it is more likely to occur in younger patients, African American women, and patients with a BRCA 1 mutation. Triple negative breast cancer can be more aggressive and difficult to treat.  Also, the cancer is more likely to spread and recur than other cancers.  Patients with triple negative breast cancer cannot be treated with two of the more notable and effective breast cancer treatments: Herceptin and hormone therapy. Although triple negative breast cancer does not respond to these standard breast cancer treatments, it has fortunately been shown to be receptive to certain chemotherapeutic regimens, and therefore chemotherapy remains the primary treatment option.

Inflammatory breast cancer is an uncommon form of invasive breast cancer accounting for 1%-3% of all breast cancers. Patients will present with skin changes such as redness or warmth. The skin may appear thick with dimpling (like an orange peel). The changes in the skin are due to cancer cells blocking the lymphatic vessels. You may not feel a single lump or tumor. The breast may become swollen, larger, tender, or itchy. It may be mistaken for an infection of the breast in the early stages. Symptoms may be initially treated with antibiotics due to this. If symptoms are caused by breast cancer, the appearance of the breast will not improve and a biopsy will be necessary to find cancer cells. This type of breast cancer tends to have a higher chance of spreading to lymph nodes.

Other Types of Breast Cancer

Pagets disease of the nipple is a type of breast cancer that starts in the breast ducts and spreads to the skin of the nipple and then to the areola (the dark circle around the nipple). It is rare, accounting for only about 1% of all cases of breast cancer. The skin of the nipple and areola often appears crusted, scaly, and red, with areas of bleeding or oozing. The woman may notice burning or itching. A nipple biopsy may be necessary. It is most always associated with either ductal carcinoma in situ (DCIS) or infiltrating ductal carcinoma. A breast lump may only be found in 50% of patients. Treatment often requires mastectomy. Prognosis is usually excellent if no lump is found in the breast and the biopsy shows DCIS. If invasive cancer is found on biopsy the cancer is stage and treated like any other invasive cancer.

Tubular carcinoma is a special-type of invasive cancer that is typically associated with limited metastatic potential and an excellent prognosis. This cancer begins inside the breast's milk duct and spreads beyond it into healthy tissue. Tubular carcinomas are usually small (about 1 cm or less) and made up of tube-shaped structures called "tubules." These tumors tend to be low-grade, meaning that their cells look somewhat similar to normal, healthy cells and tend to grow slowly. Tubular carcinomas account for less than 1-4% of all breast cancers.

Mucinous carcinoma, sometimes called colloid carcinoma, is a rare type of invasive breast cancer that is formed when cancer cells within your breast produce mucous. This mucous contains breast cancer cells that are easily distinguished from normal cells under a microscope. Together, the mucous and cancer cells form a jelly-like tumor. Most mucinous carcinomas of the breast are estrogen-receptor positive and HER2/neu negative. This type of breast cancer rarely spreads to your lymph nodes.

Papillary carcinoma is a type of ductal carcinoma in situ (DCIS). This type of breast cancer is rarely invasive, and usually stays within the milk ducts.  Papillary carcinoma typically has a better prognosis than other, more common breast cancers. The primary difference between papillary carcinoma and other types of breast cancer is that the cancer cells are arranged in finger-like projections, or papules. Under a microscope, the cells appear fern-like. Sometimes, the cancer cells are very small in size, in which case the cancer may be called micropapillary.  

Medullary carcinoma of the breast is a rare subtype of invasive ductal carcinoma (cancer that begins in the milk duct and spreads beyond it). It is called “medullary” carcinoma because the tumor is a soft, fleshy mass that resembles a part of the brain called the medulla. Medullary carcinoma cells are usually high-grade in their appearance and low-grade in their behavior. In other words, they look like aggressive, highly abnormal cancer cells, but they don’t act like them. Medullary carcinoma doesn’t grow quickly and usually doesn’t spread outside the breast to the lymph nodes. For this reason, it’s typically easier to treat than other types of breast cancer.