Breast Cancer

  • Basics

    Breast cancer is the most common cancer among women. Estimates indicate that 212,290 American women will be diagnosed with breast cancer in 2006, and about 41,000 women will die annually from this disease. It is estimated that 12% of American women will develop the disease and 3.5% will die from it.

    Late in 2006, researchers presented the results of a study of breast cancer rates at a medical meeting showing a significant drop in new cases of breast cancer since 2003. The study showed that new cases declined by 7%. Many experts attribute this decline to decreased post-menopausal hormone use that occurred after a large study that was published in 2002 linked hormone use with breast cancer.

    The incidence of breast cancer had been rising in American women for more than 30 years.Scientists have several possible explanations: 1) more cases are reported because methods of finding the disease have improved; 2) more women are living into old age (older women are at greater risk for breast cancer); and 3) many women are choosing to have children after age 30. A hormone called estrogen produced by the ovaries is thought to play a role in breast cancer. A woman who has not had children or who has put off having children will have more exposure to estrogen than a woman who gave birth at an early age.

    While the number of cases had been increasing until recently, the death rate seems to be decreasing slightly, particularly for white women, because of early detection and increased use of mammography, as well as improved treatments after surgery.

    Breast cancer is not only a serious physical disease, but it is often an emotionally draining disease as well. Intense feelings of fear, despair, loss, and loneliness are common among patients suffering from breast cancer. Issues regarding sexuality (especially if a mastectomy has been performed) often surround breast cancer. Even if you do not have to undergo a mastectomy, cancer is a word that can be very frightening, and you may find yourself needing a great deal of support from family, friends, and other people who have been diagnosed. It is important to talk with your doctor about the psychological side effects of breast cancer you may be dealing with. There are numerous support groups for women and their families to help cope with breast cancer. Your doctor or nurse can help you locate a group near you.

  • Causes

    The precise cause of breast cancer is unknown. Breast cancer can happen to anyone. Most cases of breast cancer occur in women who are not classified as high risk, a reminder that more research must be done in order to uncover possible causes.

    Breast cancer runs in families. Having a mother and/or a sister with the disease increases your risk. About a quarter of breast cancer cases occur in women who have the disease in the family.

    Breast cancer has a genetic link. Scientists have recently identified two genes (BRCA1 and BRCA2) as having a link with breast cancer. However, defects (or mutations) in these genes seem responsible for only about 5% to 10% of breast cancer cases annually. Women who have these gene mutations are much more likely to develop breast cancer, especially at younger ages, compared to the general population. Studies show that approximately 2% of women of Ashkenazi Jewish origin (Eastern European) are carriers for these mutations. Women with BRCA1 or BRCA2 mutations may be advised to begin screening at age 25 because of their higher risk of developing breast cancer. If you have a strong family history of breast cancer at a young age, have had cancer in both breasts, or were diagnosed with breast cancer before age 30, you should consider being tested for mutations in these genes.

    The female hormone called estrogen is linked to breast cancer. The role of estrogen and its relation to breast cancer is not yet completely understood. If you have never given birth, you are at greater risk for breast cancer because you have had more exposure to estrogen than women who have had a baby. This is because your body produces less estrogen when you are pregnant. Taking estrogen after menopause (hormone replacement therapy: HRT) also increases your risk. It is important to remember that taking estrogen after menopause also increases your long-term risk of heart disease and stroke. There has been a lot of discussion over the birth control pill and its possible link to breast cancer, but at this point, doctors generally agree that there is no greater risk if you are on the pill.

    Some studies suggest that a diet high in animal fat and protein may be a factor in developing breast cancer, although the results of these studies are not definite.

    Staging breast cancer helps to determining the course of treatment and the prognosis. Staging is based on the size of the tumor, how much of the breast tissue is cancerous, whether the underarm (axillary) lymph nodes are also cancerous, and whether cancer can be found in other parts of the body. The 5-year survival rate for localized breast cancer (not spread to the axillary lymph nodes) is 96%. If cancer has spread regionally, the rate is 77%. For those women who are diagnosed with metastatic disease, the 5-year survival rate is only 5 to 10%.

    The stages for breast cancer are:

    • Stage 0: This is characterized by cancer that has not spread from the breast tissue. Both DCIS and LCIS are classified as Stage 0.
    • Stage I: This is an early form of the disease; however, the cancer has invaded nearby tissue. At this stage, the tumor is a little bit less than an inch in diameter, and the cancer has not spread beyond the breast.
    • Stage II is divided into Stages IIa and IIb. It is an early form of the disease.
    • Stage IIa is defined as being either of the following: 1) the cancer is a little less than an inch in diameter, but has spread to the lymph nodes under the arm (the axillary lymph nodes); or, 2) the cancer is between one to two inches, but has not spread to the lymph nodes under the arm.
    • Stage IIb is either one of the following: 1) the cancer is between one to two inches and has spread to the lymph nodes under the arm; or, 2) the cancer is larger than two inches, but it has not spread to the lymph nodes.
    • Stage III is divided into Stages IIIa and IIIb. This stage is considered to be locally advanced cancer.
    • Stage IIIa is defined by either of the following: 1) the cancer is smaller than two inches and has spread to the lymph nodes under the arm, and the lymph nodes are attached to each other or to other structures; or, 2) the cancer is larger than two inches and has spread to the lymph nodes under the arm.
    • Stage IIIb is defined by either of the following: 1) the cancer has spread to tissues near the breast (skin or chest wall, including the ribs and the muscles in the chest); or, 2) the cancer has spread to lymph nodes inside the chest wall along the breast bone.
    • Stage IV: Cancer has spread to other parts of the body (metastatic cancer). The five-year survival rate for cancer diagnosed at this stage is 5 to 10%.
    • Inflammatory breast cancer is a rare form of breast cancer that you can see. The breast looks inflamed and red. The skin may show signs of ridges or dimples or pits. Inflammatory breast cancer tends to spread quickly. It is usually classified as Stage IIIb, with a five-year survival rate of 50%.
    • Recurrent cancer: In recurrent cancer, the disease has come back despite treatment. The cancer can grow in the breast or chest wall (local recurrence), or in distant organs, bones, or lymph nodes (distant metastases). Some local recurrences can be curable, but distant metastases are almost never curable, even though some patients can live a long time. Most recurrences happen two to three years after the initial cancer diagnosis, although recurrences have been known to happen much earlier and much later.

    Different types of tumors cause different types of breast cancer and grow in different areas of the breast.

    Breast cancer is classified as being non-invasive or invasive Figure 01. Non-invasive cancer (in situ carcinoma) is an early form of cancer that has not attacked any other tissue or grown beyond the breast ducts or lobules. Depending on when it is discovered and other factors, it can be cured. Two types of non-invasive cancer are ductal carcinoma in situ (DCIS) or lobular carcinoma in situ (LCIS). Both can turn into invasive cancer. Both of these types of cancer are considered to be Stage 0. Invasive cancer is cancer that has spread to other tissues. There are several different types of invasive cancer.

    Click to enlarge: Anatomy of the female breast

    Figure 01. Anatomy of the female breast

    The two types of non-invasive cancer (DCIS and LCIS) are early forms of the disease. Ductal carcinoma in situ (DCIS) generally starts in the channels that carry milk out of the breast (milk ducts). DCIS can be felt during a breast examination, but lately, it is more often detected by mammography. DCIS can develop before or after you stop menstruating (menopause). Surgery is often used to treat DCIS.

    Lobular carcinoma in situ (LCIS) generally starts in the milk-producing glands of the breast. LCIS is not usually detected during a breast examination or a mammogram, but may be an incidental finding by a biopsy. A biopsy is a test done to determine whether or not a lump is cancerous. For a biopsy, a small amount of tissue is taken from the site and sent to a lab for testing. LCIS, which tends to develop before a woman reaches menopause, was once considered to be a pre-cancerous mass of cells. It is now thought to indicate an increased risk for developing a common type of invasive cancer. A woman who is diagnosed with LCIS is watched very carefully to detect any changes and to determine what kind of treatment should follow.

    Invasive breast cancer is cancer that has spread outside the ducts and lobules to the surrounding breast tissues.

    The two main types of invasive breast cancer are invasive ductal carcinoma and invasive lobular carcinoma. About 70% of breast cancer patients have invasive ductal carcinoma. This cancer develops in the milk ducts and can spread into the fatty breast tissue. In many cases it may then spread to other parts of the body such as the lymphatic system. Only about 10% of breast cancer patients have invasive lobular carcinoma. This cancer develops in the milk-producing lobes and can spread to the fatty breast tissue and elsewhere in the body.

    Metastatic breast cancer refers to cancer that has left the breast and spread to distant sites. The most common sites are the lungs, liver, bones, brain, and skin. Cancer can appear in these areas years after the initial diagnosis. Metastatic breast cancer is not curable, although women can live many years with the disease.

Recommended Reading

Meet the Pharmacists

I'm Kristen Dore, PharmD. Welcome to PDR Health!

Check out my latest blog post on heartburn medication

Breast Cancer Related Drugs

Breast Cancer Related Conditions