What is breast cancer

: Breast Cancer

Key Points for This Section

• Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.
• Age and health history can affect the risk of developing breast cancer.
• Breast cancer is sometimes caused by inherited gene mutations (changes).
• Tests that examine the breasts are used to detect (find) and diagnose breast cancer.
• Certain factors affect prognosis (chance of recovery) and treatment options.

Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.

The breast is made up of lobes and ducts. Each breast has 15 to 20 sections called lobes, which have many smaller sections called lobules. Lobules end in dozens of tiny bulbs that can produce milk. The lobes, lobules, and bulbs are linked by thin tubes called ducts.

Each breast also has blood vessels and lymph vessels. The lymph vessels carry an almost colorless fluid called lymph. Lymph vessels lead to organs called lymph nodes. Lymph nodes are small bean-shaped structures that are found throughout the body. They filter substances in lymph and help fight infection and disease. Clusters of lymph nodes are found near the breast in the axilla (under the arm), above the collarbone, and in the chest.

The most common type of breast cancer is ductal carcinoma, which begins in the cells of the ducts. Cancer that begins in the lobes or lobules is called lobular carcinoma and is more often found in both breasts than are other types of breast cancer. Inflammatory breast cancer is an uncommon type of breast cancer in which the breast is warm, red, and swollen.

Age and health history can affect the risk of developing breast cancer.

Anything that increases your chance of getting a disease is called a risk factor. Risk factors for breast cancer include the following:

• Older age.
• Menstruating at an early age.
• Older age at first birth or never having given birth.
• A personal history of breast cancer or benign (noncancer) breast disease.
• A mother or sister with breast cancer.
• Treatment with radiation therapy to the breast/chest.
• Breast tissue that is dense on a mammogram.
• Taking hormones such as oestrogen and progesterone.
• Drinking alcoholic beverages.
• Being white.

Breast cancer is sometimes caused by inherited gene mutations (changes).

The genes in cells carry the hereditary information that is received from a person’s parents. Hereditary breast cancer makes up approximately 5% to 10% of all breast cancer. Some altered genes related to breast cancer are more common in certain ethnic groups.

Women who have an altered gene related to breast cancer and who have had breast cancer in one breast have an increased risk of developing breast cancer in the other breast. These women also have an increased risk of developing ovarian cancer, and may have an increased risk of developing other cancers. Men who have an altered gene related to breast cancer also have an increased risk of developing this disease. (For more information, refer to the summary on Male Breast Cancer Treatment.)

Tests have been developed that can detect altered genes. These genetic tests are sometimes done for members of families with a high risk of cancer. (Refer to the summaries on Screening for Breast Cancer, Prevention of Breast Cancer, and Genetics of Breast and Ovarian Cancer for more information.)

Tests that examine the breasts are used to detect (find) and diagnose breast cancer.

A doctor should be seen if changes in the breast are noticed. The following tests and procedures may be used:

• Mammogram: An x-ray of the breast.
  
• Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. If a lump in the breast is found, the doctor may need to cut out a small piece of the lump. Four types of biopsies are as follows:
o Excisional biopsy: The removal of an entire lump or suspicious tissue. o Incisional biopsy: The removal of part of a lump or suspicious tissue. o Core biopsy: The removal of part of a lump or suspicious tissue using a wide needle. o Needle biopsy or fine-needle aspiration biopsy: The removal of part of a lump, suspicious tissue, or fluid, using a thin needle.
• Oestrogen and progesterone receptor test: A test to measure the amount of oestrogen and progesterone (hormones) receptors in cancer tissue. If cancer is found in the breast, tissue from the tumour is examined in the laboratory to find out whether oestrogen and progesterone could affect the way cancer grows. The test results show whether hormone therapy may stop the cancer from growing.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) and treatment options depend on the following:

• The stage of the cancer (whether it is in the breast only or has spread to lymph nodes or other places in the body).
• The type of breast cancer.
• Oestrogen-receptor and progesterone-receptor levels in the tumour tissue.
• A woman’s age, general health, and menopausal status (whether a woman is still having menstrual periods).
• Whether the cancer has just been diagnosed or has recurred (come back).

Stages of Breast Cancer

Key Points for This Section

• After breast cancer has been diagnosed, tests are done to find out if cancer cells have spread within the breast or to other parts of the body.
• The following stages are used for breast cancer:
o Stage 0 (carcinoma in situ) o Stage I o Stage IIA o Stage IIB o Stage IIIA o Stage IIIB o Stage IIIC o Stage IV After breast cancer has been diagnosed, tests are done to find out if cancer cells have spread within the breast or to other parts of the body. The process used to find out whether the cancer has spread within the breast or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. The following stages are used for breast cancer: Stage 0 (carcinoma in situ) There are 2 types of breast carcinoma in situ:
• Ductal carcinoma in situ (DCIS) is a noninvasive, precancerous condition in which abnormal cells are found in the lining of a breast duct. The abnormal cells have not spread outside the duct to other tissues in the breast. In some cases, DCIS may become invasive cancer and spread to other tissues, although it is not known at this time how to predict which lesions will become invasive.
• Lobular carcinoma in situ (LCIS) is a condition in which abnormal cells are found in the lobules of the breast. This condition seldom becomes invasive cancer; however, having lobular carcinoma in situ in one breast increases the risk of developing breast cancer in either breast.
Stage I In stage I, the tumour is 2 centimeters or smaller and has not spread outside the breast. Stage IIA In stage IIA:
• no tumour is found in the breast, but cancer is found in the axillary lymph nodes (the lymph nodes under the arm); or
• the tumour is 2 centimeters or smaller and has spread to the axillary lymph nodes; or
• the tumour is larger than 2 centimeters but not larger than 5 centimeters and has not spread to the axillary lymph nodes.
Stage IIB In stage IIB, the tumour is either:
• larger than 2 centimeters but not larger than 5 centimeters and has spread to the axillary lymph nodes; or
• larger than 5 centimeters but has not spread to the axillary lymph nodes.
Stage IIIA In stage IIIA:
• no tumour is found in the breast, but cancer is found in axillary lymph nodes that are attached to each other or to other structures; or
• the tumour is 5 centimeters or smaller and has spread to axillary lymph nodes that are attached to each other or to other structures; or
• the tumour is larger than 5 centimeters and has spread to axillary lymph nodes that may be attached to each other or to other structures.
Stage IIIB In stage IIIB, the cancer may be any size and:
• has spread to tissues near the breast (the skin or chest wall, including the ribs and muscles in the chest); and
• may have spread to lymph nodes within the breast or under the arm.
Stage IIIC In stage IIIC, the cancer:
• has spread to lymph nodes beneath the collarbone and near the neck; and
• may have spread to lymph nodes within the breast or under the arm and to tissues near the breast.
Stage IIIC breast cancer is divided into operable and inoperable stage IIIC. In operable stage IIIC, the cancer:
• is found in 10 or more of the lymph nodes under the arm; or
• is found in the lymph nodes beneath the collarbone and near the neck on the same side of the body as the breast with cancer; or
• is found in lymph nodes within the breast itself and in lymph nodes under the arm.
In inoperable stage IIIC breast cancer, the cancer has spread to the lymph nodes above the collarbone and near the neck on the same side of the body as the breast with cancer. Stage IV In stage IV, the cancer has spread to other organs of the body, most often the bones, lungs, liver, or brain. Inflammatory Breast Cancer In inflammatory breast cancer, the breast looks red and swollen and feels warm. The redness and warmth occur because the cancer cells block the lymph vessels in the skin. The skin of the breast may also show the pitted appearance called peau d’orange (like the skin of an orange). Inflammatory breast cancer may be stage IIIB, stage IIIC, or stage IV. Recurrent Breast Cancer Recurrent breast cancer is cancer that has recurred (come back) after it has been treated. The cancer may come back in the breast, in the chest wall, or in other parts of the body. Treatment Option Overview Key Points for This Section
• There are different types of treatment for patients with breast cancer.
• Four types of standard treatment are used:
o Surgery o Radiation therapy o Chemotherapy o Hormone therapy
• New types of treatment are being tested in clinical trials. These include the following:
o Sentinel lymph node biopsy followed by surgery o High-dose chemotherapy with stem cell transplant o Monoclonal antibodies as adjuvant therapy There are different types of treatment for patients with breast cancer. Different types of treatment are available for patients with breast cancer. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. Before starting treatment, patients may want to think about taking part in a clinical trial. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Clinical trials are taking place in many parts of the country. Information about ongoing clinical trials is available from the NCI Web site. Choosing the most appropriate cancer treatment is a decision that ideally involves the patient, family, and health care team. Four types of standard treatment are used: Surgery Most patients with breast cancer have surgery to remove the cancer from the breast. Some of the lymph nodes under the arm are usually taken out and looked at under a microscope to see if they contain cancer cells. Breast-conserving surgery, an operation to remove the cancer but not the breast itself, includes the following:
• Lumpectomy: A surgical procedure to remove a tumour (lump) and a small amount of normal tissue around it.
• Partial mastectomy: A surgical procedure to remove the part of the breast that contains cancer and some normal tissue around it. This procedure is also called a segmental mastectomy.
Patients who are treated with breast-conserving surgery may also have some of the lymph nodes under the arm removed for biopsy. This procedure is called lymph node dissection. It may be done at the same time as the breast-conserving surgery or after. Lymph node dissection is done through a separate incision. Other types of surgery include the following:
• Total mastectomy: A surgical procedure to remove the whole breast that contains cancer. This procedure is also called a simple mastectomy. Some of the lymph nodes under the arm may be removed for biopsy at the same time as the breast surgery or after. This is done through a separate incision.
• Modified radical mastectomy: A surgical procedure to remove the whole breast that contains cancer, many of the lymph nodes under the arm, the lining over the chest muscles, and sometimes, part of the chest wall muscles.
• Radical mastectomy: A surgical procedure to remove the breast that contains cancer, chest wall muscles under the breast, and all of the lymph nodes under the arm. This procedure is sometimes called a Halsted radical mastectomy.
Even if the doctor removes all of the cancer that can be seen at the time of surgery, the patient may be given radiation therapy, chemotherapy, or hormone therapy after surgery to try to kill any cancer cells that may be left. Treatment given after surgery to increase the chances of a cure is called adjuvant therapy. If a patient is going to have a mastectomy, breast reconstruction (surgery to rebuild a breast’s shape after a mastectomy) may be considered. Breast reconstruction may be done at the time of the mastectomy or at a future time. The reconstructed breast may be made with the patient’s own (nonbreast) tissue or by using implants filled with saline or silicone gel. The Food and Drug Administration (FDA) has decided that breast implants filled with silicone gel may be used only in clinical trials. Before the decision to get an implant is made, patients can call the FDA’s Center for Devices and Radiologic Health at 1-888-INFO-FDA (1-888-463-6332) for more information. Radiation therapy Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type and stage of the cancer being treated. Chemotherapy Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping the cells from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the spinal column, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). The way the chemotherapy is given depends on the type and stage of the cancer being treated. Hormone therapy Hormone therapy is a cancer treatment that removes hormones or blocks their action and stops cancer cells from growing. Hormones are substances produced by glands in the body and circulated in the bloodstream. The presence of some hormones can cause certain cancers to grow. If tests show that the cancer cells have places where hormones can attach (receptors), drugs, surgery, or radiation therapy are used to reduce the production of hormones or block them from working. Hormone therapy with tamoxifen is often given to patients with early stages of breast cancer and those with metastatic breast cancer (cancer that has spread to other parts of the body). Hormone therapy with tamoxifen or oestrogens can act on cells all over the body and may increase the chance of developing endometrial cancer. Women taking tamoxifen should have a pelvic examination every year to look for any signs of cancer. Any vaginal bleeding, other than menstrual bleeding, should be reported to a doctor as soon as possible. New types of treatment are being tested in clinical trials. These include the following: Sentinel lymph node biopsy followed by surgery Sentinel lymph node biopsy is the removal of the sentinel lymph node (the first lymph node the cancer is likely to spread to from the tumour) during surgery. A radioactive substance and/or blue dye is injected near the tumour. The substance or dye flows through the lymph ducts to the lymph nodes. The first lymph node to receive the substance or dye is removed for biopsy. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are not found, it may not be necessary to remove more lymph nodes. After the sentinel lymph node biopsy, the surgeon removes the tumour (breast-conserving surgery or mastectomy). Enlarge Sentinel lymph node biopsy. First of three panel illustration showing radioactive substance and/or blue dye is injected near the tumour, the injected material is followed visually or with a probe, and the first lymph nodes to take up the material are removed and checked for cancer cells. Sentinel lymph node biopsy. Second of three panel illustration showing radioactive substance and/or blue dye is injected near the tumour, the injected material is followed visually or with a probe, and the first lymph nodes to take up the material are removed and checked for cancer cells. Sentinel lymph node biopsy. Third of three panel illustration showing radioactive substance and/or blue dye is injected near the tumour, the injected material is followed visually or with a probe, and the first lymph nodes to take up the material are removed and checked for cancer cells. Sentinel lymph node biopsy. Radioactive substance and/or blue dye is injected near the tumour (first panel), the injected material is followed visually or with a probe (middle panel), and the first lymph nodes to take up the material are removed and checked for cancer cells (last panel). High-dose chemotherapy with stem cell transplant High-dose chemotherapy with stem cell transplant is a method of giving high doses of chemotherapy and replacing blood-forming cells destroyed by the cancer treatment. Stem cells (immature blood cells) are removed from the blood or bone marrow of the patient or a donor and are frozen and stored. After the chemotherapy is completed, the stored stem cells are thawed and given back to the patient through an infusion. These reinfused stem cells grow into (and restore) the body’s blood cells. Studies have shown that high-dose chemotherapy followed by stem cell transplant does not work better than standard chemotherapy in the treatment of breast cancer. Doctors have decided that, for now, high-dose chemotherapy should be tested only in clinical trials. Before taking part in such a trial, women should talk with their doctors about the serious side effects, including death, that may be caused by high-dose chemotherapy. Monoclonal antibodies as adjuvant therapy Monoclonal antibody therapy is a cancer treatment that uses antibodies made in the laboratory, from a single type of immune system cell. These antibodies can identify substances on cancer cells or normal substances that may help cancer cells grow. The antibodies attach to the substances and kill the cancer cells, block their growth, or keep them from spreading. Monoclonal antibodies are given by infusion. They may be used alone or to carry drugs, toxins, or radioactive material directly to cancer cells. Monoclonal antibodies are also used in combination with chemotherapy as adjuvant therapy. Trastuzumab (Herceptin) is a monoclonal antibody that blocks the effects of the growth factor protein HER2, which transmits growth signals to breast cancer cells. About one-fourth of patients with breast cancer have tumours that may be treated with trastuzumab combined with chemotherapy. Treatment Options by Stage Ductal Carcinoma In Situ (DCIS) Treatment of ductal carcinoma in situ (DCIS) may include the following:
• Breast-conserving surgery with or without radiation therapy or hormone therapy.
• Total mastectomy with or without hormone therapy.
• Clinical trials testing breast-conserving surgery and hormone therapy with or without radiation therapy.
Lobular Carcinoma In Situ (LCIS) Treatment of lobular carcinoma in situ (LCIS) may include the following:
• Biopsy to diagnose the LCIS followed by regular examinations and regular mammograms to find any changes as early as possible. This is referred to as observation.
• Tamoxifen to reduce the risk of developing breast cancer.
• Bilateral prophylactic mastectomy. This treatment choice is sometimes used in women who have a high risk of getting breast cancer. Most surgeons believe that this is a more aggressive treatment than is needed.
• Clinical trials testing cancer prevention drugs.
Stage I, Stage II, Stage IIIA, and Operable Stage IIIC Breast Cancer Treatment of stage I, stage II, stage IIIA , and operable stage IIIC breast cancer may include the following:
• Breast-conserving surgery to remove only the cancer and some surrounding breast tissue, followed by lymph node dissection and radiation therapy.
• Modified radical mastectomy with or without breast reconstruction surgery.
• A clinical trial evaluating sentinel lymph node biopsy followed by surgery.
Adjuvant therapy (treatment given after surgery to increase the chances of a cure) may include the following:
• Radiation therapy to the lymph nodes near the breast and to the chest wall after a modified radical mastectomy.
• Systemic chemotherapy with or without hormone therapy.
• Hormone therapy.
• A clinical trial of trastuzumab (Herceptin) combined with systemic chemotherapy.
Stage IIIB, Inoperable Stage IIIC, Stage IV, and Metastatic Breast Cancer Stage IIIB and inoperable stage IIIC breast cancer Treatment of stage IIIB and inoperable stage IIIC breast cancer may include the following:
• Systemic chemotherapy.
• Systemic chemotherapy followed by surgery (breast-conserving surgery or total mastectomy), with lymph node dissection followed by radiation therapy. Additional systemic therapy (chemotherapy, hormone therapy, or both) may be given.
• Clinical trials testing new anticancer drugs, new drug combinations, and new ways of giving treatment.
Stage IV and metastatic breast cancer Treatment of stage IV or metastatic breast cancer may include the following:
• Hormone therapy and/or systemic chemotherapy with or without trastuzumab (Herceptin).
• Radiation therapy and/or surgery for relief of pain and other symptoms.
• Clinical trials testing new systemic chemotherapy and/or hormone therapy.
• Clinical trials of new combinations of trastuzumab (Herceptin) with anticancer drugs.
• Clinical trials testing other approaches, including high-dose chemotherapy with stem cell transplant.
• Bisphosphonate drugs to reduce bone disease and pain when cancer has spread to the bone.
Treatment Options for Inflammatory Breast Cancer Treatment of inflammatory breast cancer may include the following:
• Systemic chemotherapy.
• Systemic chemotherapy followed by surgery (breast-conserving surgery or total mastectomy), with lymph node dissection followed by radiation therapy. Additional systemic therapy (chemotherapy, hormone therapy, or both) may be given.
• Clinical trials testing new anticancer drugs, new drug combinations, and new ways of giving treatment.
Treatment Options for Recurrent Breast Cancer Treatment of recurrent breast cancer (cancer that has come back after treatment) in the breast or chest wall may include the following:
• Surgery (radical or modified radical mastectomy), radiation therapy, or both.
• Systemic chemotherapy or hormone therapy.
• A clinical trial of trastuzumab (Herceptin) combined with systemic chemotherapy.