Breast Cancer Overview

Breast cancer is the second most common form of cancer in women after non-melanoma skin cancer. It is also the second most common cause of cancer death in women after lung cancer.

Although breast cancer occurs more often in women, men also get breast cancer. According to the National Cancer Institute, the estimated new cases and deaths from breast cancer in 2007:

• 178,480 women and 2,030 men will be diagnosed with breast cancer.
• 40,460 women and 450 men will die from breast cancer.

Today, breast cancer cases are being diagnosed at an earlier, more treatable stage. Breast-sparing surgeries now make radical mastectomies unnecessary for many people. Moreover, breast cancer treatments such as radiation therapy, chemotherapy, hormone therapy, targeted therapy, and bisphosphonates are more successful at destroying breast cancer cells in the body.

Breast cancer death rates are declining. According to the American Cancer Society (ACS), there currently are about two and a half million breast cancer survivors in the United States.

Cancer

Cancer is actually a group of over 100 different diseases that all cause the uncontrolled growth of abnormal cells in the body, resulting in damage to DNA (deoxyribonucleic acid, the genetic material of the genes). An abnormal growth of cells is called a tumor, which may be either benign or malignant. A benign tumor is not cancer. It grows slowly and does not spread to other parts of the body. A malignant tumor is cancer. It spreads (metastasizes) to the surrounding tissue and may spread to other parts of the body.

The most common forms of cancer in the United States are (in order):

• Skin cancer
• Lung cancer
• Breast cancer in women
• Prostate cancer in men
• Colon cancer

Cancer is the second leading cause of death. Heart disease is the first. The most common types of cancer deaths are (in order):

• Lung cancer
• Breast cancer in women
• Prostate cancer in men
• Colon cancer
• Pancreatic cancer

The breasts

The breasts are mammary (milk-secreting) glands, which usually are well developed in adult females and rudimentary in males. The parts of the breast are the:

Lobules

• Lobules contain glands that can produce milk in females.
• The male breast contains few, if any, lobules.

Ducts

• Ducts are tiny tubes that carry milk from the lobules to the nipple in females.
• The male breast contains undeveloped ducts.
  

Supporting tissue

• The supporting tissue of the breast is made up of fatty and connective tissue, blood vessels, and lymph vessels.
• Blood vessels carry blood to and from the breast.
• Lymphatic vessels carry lymph (a clear fluid containing immune system cells and waste products) and lead to lymph nodes. The lymph nodes help the body fight infection, and remove bacteria and cancer cells from the lymph fluid. They are located in the armpit, above the collarbone, behind the breastbone, and in other parts of the body.

Children have a small amount of breast tissue. At puberty:

• Female hormones cause the breast ducts to grow, the lobules to form, and the supporting tissue to get larger.
• Male hormones prevent the future growth of breast tissue.

It is believed that the higher incidence of breast cancer in females than males may be due to a combination of the greater number of breast cells in females and the action of the female hormones on these cells.

Breast cancer types

Breast cancer is caused by the development of malignant (cancerous) cells in the breast, which:

• Grow and divide abnormally.
• Invade local breast tissue.
• May spread throughout the body (metastasize).

There are two major types of breast cancer:

• Ductal carcinoma
  80% of breast cancers occur in the ducts. Two forms of ductal carcinoma are:
  • Ductal carcinoma in situ
    The cancer cells only line the milk ducts and have not spread to other parts of the breast tissue ("in situ" means "in place").
  • Invasive ductal carcinoma
    The cancer cells spread to other parts of the breast tissue and may spread to other parts of the body.
• Lobular carcinoma
  10-15% of breast cancers occur in the lobules. Two forms of lobular carcinoma are:
  • Lobular carcinoma in situ
    The cancer cells are only in the breast lobules and rarely spread to other breast tissue.
  • Invasive lobular carcinoma
    The cancer cells spread to other parts of the breast tissue and may spread to other parts of the body

Uncommon types of breast cancer (5-10%) that may develop include:

• Paget's disease of nipple
  Paget's disease of nipple is a type of breast cancer that affects the nipple and areola (the colored skin surrounding the nipple).
• Inflammatory breast cancer
  Inflammatory breast cancer is an aggressive cancer that causes breast swelling and redness.

The types of breast cancer found in men are:

• Ductal carcinoma in situ
• Invasive ductal carcinoma
• Paget's disease of the nipple
• Inflammatory breast cancer

Metastatic breast cancer

Metastatic breast cancer occurs when breast cancer cells enter the bloodstream or lymphatic system, and then spread to other parts of the body. When this occurs, a cancerous tumor may form in a different organ. Breast cancer is most likely to spread to the:

• Lymph nodes near the breast
• Lungs
• Liver
• Bone
• Brain

Recurrent breast cancer

Sometimes breast cancer returns after being undetectable for months or even years. Recurrent breast cancer may return in:

• The same location in the breast.
• Nearby tissues.
• Other parts of the body.