Types of Breast Cancer

There are two kinds of breast cancer, "invasive" and "noninvasive."

Invasive Breast Cancer
Invasive breast cancer is the more serious of the two types. It happens when abnormal cells from inside the breast's lobules or ducts spread into the surrounding breast tissue. This allows the cancer to spread to the lymph nodes and, in advanced stages, to areas such as the liver, lungs, and bones.

Healthcare professionals now believe that cancer cells can spread from the breast through the blood and lymphatic system at early stages of the disease, even though these spreading cancer cells do not always survive.

A phrase that you may hear from your healthcare team is the term "locally advanced" breast cancer. This is usually referred to as cancer that has not spread to another area in the body. However, the following issues may nonetheless have occurred¹:

• The cancer in the breast may be bigger than 5 centimeters across
• The cancer may have spread into the skin or muscle of the chest, or
• There may be cancer in the lymph nodes under the arm

Locally advanced breast cancer can be any or all of the above. Locally advanced could mean either stage II or stage III breast cancer (see Diagnosis and Staging).

Noninvasive Breast Cancer
"In situ" means "in place" and the term "carcinoma in situ" is used to describe this condition because the cancer cells remain in their original location and do not spread, or "metastasize" to the surrounding tissue or beyond. When abnormal cells grow inside the lobules, it is called "lobular carcinoma in situ." When abnormal cells grow inside the milk ducts, it is called "ductal carcinoma in situ."¹

Carcinoma in situ is thought of as a precancerous condition because it can develop into or raise your risk for a more serious, invasive cancer.¹

Subtypes of Breast Cancer
Many types of breast cancer are diagnosed, and some of them are very rare. In some instances a breast tumor can be a combination of these types, and even contain a mixture of invasive and noninvasive types.²

• Ductal carcinoma in situ (also called "DCIS")
  The most common type of noninvasive breast cancer, DCIS is found only in the ducts, and has not spread. Nearly all women with cancer at this stage can be cured. Early diagnosis is possible with a mammogram.²
• Lobular carcinoma in situ (also called "LCIS")
  Begins in the milk-making glands but has not spread through the wall of the lobules. Although not a true cancer, having LCIS increases a woman's risk of getting cancer later. Women with LCIS should definitely screen for cancer.²
• Invasive (infiltrating) ductal carcinoma (also called "IDC")
  The most common form of breast cancer, IDC starts in a milk passage or duct, breaks through the wall of the duct, and invades the breast tissue. From there it can spread to other parts of the body. IDC accounts for about 8 out of 10 invasive breast cancers.²
• Invasive (infiltrating) lobular carcinoma (also called "ILC")
  Starts in the milk glands or lobules, where it can spread to other parts of the body. ILC accounts for roughly 1 out of 10 invasive breast cancers.²
• Inflammatory breast cancer (also called "IBC")
  A rare type of invasive breast cancer that accounts for about 1% to 3% of all breast cancers. Usually there is no lump or tumor. Instead, IBC makes the skin of the breast look red and feel warm, and gives the skin a thick, pitted appearance that are not caused by inflammation or infection, but by cancer cells blocking lymph vessels in the skin. IBC is often mistaken for an infection in its early stages, and may not appear on a mammogram.²

A risk factor is something that can affect a person's chance of getting a disease such as breast cancer.²

Risk Factors
The exact cause of breast cancer remains unknown, although several risk factors have been linked to the disease. Some risk factors, such as smoking, can be controlled. Others, like a person's age, can't be changed. Having one or more risk factors does not mean that a person will get the disease.³

Now let's journey to Diagnosis and Staging.

References:

1. National Cancer Institute. Staging. Available at:
   http://www.cancer.gov/cancertopics/wyntk/breast/page9. Accessed Arpil 14, 2008.
2. American Cancer Society. What Is Breast Cancer? Available at:
   http://www.cancer.org/docroot/CRI/content/CRI_2_2_1X_What_is_breast_cancer_5.asp.
   Accessed March 3, 2008.
3. American Cancer Society. What Are the Risk Factors for Breast Cancer? Available at:
   http://www.cancer.org/docroot/CRI/content/….
   Accessed March 3, 2008.