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Breast Cancer

Anatomical facts:

The breasts are a pair of glands capable of producing milk for nursing babies. These organs have a complex structure made of lobules, ducts, and fatty connective tissue. The lobules are small glands that produce milk; the ducts are thin, hollow tubes that deliver the milk from the lobules to the nipples, which is located in the center of a dark area of skin called the areola. Fat and ligament tissues fill the spaces between the lobules and duds. The breasts also contain blood vessels and lymphatic vessels that drain lymphatic fluid to lymph nodes.

Breast cancer facts

Breast cancer is the most common cancer among women in the United States. Approximately 180,000 new cases of invasive breast cancer and 60,000 cases of noninvasive breast cancer are diagnosed every year. Men can develop breast cancer, but women are diagnosed with breast cancer in far greater numbers. Breast cancer is the second leading cause of cancer death among American women after lung cancer. Death rates have been declining in the past few decades, due to earlier detection and improved treatment. Wide use of regular mammograms, which can detect breast lumps before they can be felt in a physical exam, has contributed greatly to the improvement in cure rates for this type of cancer.

Breast cancer and genetics

Breast cancer is one of the few cancers for which specific inherited genetic mutations have been identified as causes. The most common mutations occur on the BRCAI and BRCA2 genes, but other genetic mutations have been identified as well. Only 5-10% of breast cancers occur among women who inherited an abnormal gene. Another risk factor for breast cancer is exposure to estrogen; women with a long menstrual history (women who started to menstruate at an early age and/or stopped menstruating at a late age), women who have never had children or have had abortions, and women taking hormone replacement therapy (HRT) after menopause have an increased risk. Obese women have a higher risk because their bodies produce more estrogen than normal-weight women. Women who have had previous breast biopsies, previous breast cancer, and previous radiation therapy to the chest area also have a higher risk.

Development of breast cancer

Most breast tumors develop in the ducts, and some develop in the lobules. Ductal and lobular carcinomas are the most common cell types. Breast cancer is divided into two major groups: noninvasive and invasive (infiltrating). The noninvasive types are ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS). In both these conditions, the malignant cells are confined to the lobules or ducts and have not spread into the connective tissue of the breast or lymph nodes. DCIS tumors may become invasive if left untreated. Surgery in combination with radiation therapy is the standard care for DCIS and has very high cure rates. LCIS is not considered a true cancer because it does not turn into invasive cancer, but women with a history of LCIS have a higher risk of developing an invasive breast cancer in both breasts and need to be monitored closely.

More than 80% of invasive breast cancers are invasive ductal carcinomas (IDC). About 10% are invasive lobular carcinomas (ILC). The rest are rare types such as medullary carcinoma, colloid carcinoma, mucinous carcinoma, and tubular carcinoma. These rare types have a slightly better prognosis than IDC or ILC, but all invasive breast cancers are treated in a similar manner according to stage. Inflammatory breast cancer (IBC) is a rare subtype of invasive breast cancer that has a high likelihood of spreading and a worse prognosis than invasive ductal or lobular cancers. Paget’s disease of the nipple is another rare type of breast cancer that starts in the ducts and spreads to the skin of the nipple and areola.

Treatment for breast cancer

The treatment of breast cancer depends on various factors like location and size of tumor, type of cancer, general health of the patient and the stage at which the disease is diagnosed.

The main options of treatment are the following:

  • Surgery
  • Radiation therapy
  • Chemotherapy
  • Hormone therapy
  • High-dose chemotherapy with stem cell transplant

All these forms of treatment can be used alone or in combination.

Surgery

Surgery is the most utilized treatment at any stage for breast cancer. The primary goal of surgery is to remove as much of the cancerous tissue as possible. In order to reduce the chances of recurrence, some of the surrounding tissue is also removed by the surgeon. Surgery may also be done to detect the spread of cancer to other tissues by biopsy of lymph nodes, to restore the shape of breasts after surgery or to relieve pain and symptoms for patients at an advanced stage.

Types of surgery:

Lumpectomy: It involves the removal of the cancerous lump on the breast and a portion of the tissue surrounding the lump.

Quadrantectomy: It involves the removal of a quarter of the breast.

Mastectomy: It involves the removal of the whole breast affected with cancer.

Lymph nodes surgery: It involves the removal of lymph nodes where cancer has or may have spread.

Adjuvant and Neoadjuvant breast cancer treatment

Treatment done after surgery is usually called adjuvant therapy. It mainly aims to kill those cancer cells which have spread from the site of cancer to other parts of the body and could not be cleared by surgery. There are different forms of adjuvant therapy such as chemotherapy, radiation therapy and hormone therapy.

All these forms of therapy may also be used before surgery to reduce the size of tumor. This kind of treatment is called neo-adjuvant therapy. The neoadjuvant therapy has developed recently. It can be used both for inoperable breast cancers and for conservation of breasts.

Radiotherapy

Radiotherapy is used to destroy tumor cells after surgery. Radiation decreases the chances that the disease may recur. It is mostly done after lumpectomy.

Radiation can be given either externally or internally.

External radiation therapy: A beam of radiation from a machine outside the body is aimed at the affected site of the patient’s body.

Internal radiation therapy or brachytherapy: Radioactive substance inside small pellets is placed near the affected region. Cancer cells are killed by the radiations emitted from the radioactive substances.

Hormone therapy

Hormone therapy is a kind of treatment in which the activity or synthesis of hormones is changed. Some hormones help in the growth and survival of some kind of cancer cells. A substance which interferes with the interaction of the hormones with cancer cells thus helps to prevent the growth of cancer cells or kill them. Estrogen receptor positive cancers can be treated with a drug called tamoxifen. Another drug called anastrozole, an aromatase inhibitor, can also be used to inhibit estrogen.

Chemotherapy

Chemotherapy is the use of drugs for cancer treatment.Chemotherapy may be taken alone or with other treatments, such as surgery or radiation. When drugs are administered by mouth or through a vein, then this kind of chemotherapy is called systemic chemotherapy. This form of chemotherapy is used when cancer has spread all throughout the body and surgery is not possible.

Targeted therapy

Targeted therapy refers to the use of drugs that specifically kills only cancer cells without damaging normal cells. There are different types of targeted therapy for the treatment of breast cancer:

Treatment with monoclonal antibodies: Monoclonal antibodies can inhibit the growth of cancer by binding to proteins on the cancer cells. Antibodies can also interfere with signaling pathways and inhibit angiogenesis. They may also carry drugs, radioactive materials or toxins with it to the target cancer cells. HER-2/neu gene amplification has been associated with the development of breast cancer. Trastuzumab (Herceptin), a monoclonal antibody against HER2 can be used to treat breast cancer.

Treatment with tyrosine kinase inhibitors: Tyrosine kinase inhibitors such as Lapatinib can block the action of HER2 protein needed for tumors to grow. It can be used after treatment with trastuzumab.

Treatment with PARP inhibitors: PARP inhibitors prevent repair of DNA to cause death of cancer cells.

High-dose chemotherapy and stem cell transplantation

In this therapy, the patient is given high doses of chemotherapy, which is more efficient than standard chemotherapy. High dose chemotherapy also kills the hematopoietic stem cells of bone marrow. These cells give rise to blood cells. To compensate for this loss, the chemotherapy treated patients are then infused with stem cells which are previously collected from the patient and frozen. This form of therapy is still under investigation.

Clinical trials

Clinical trials refer to those kinds of treatment which are not yet standardized. It is a part of research that aims to develop better strategies for the treatment of cancer. Patients may willingly participate in clinical trials.

References

Makhoul I, Kiwan E. Neoadjuvant systemic treatment of breast cancer. J Surg Oncol. 2011 Mar 15;103(4):348-57.

Ahmad Awadaa, Ivana Bozovic-Spasojevica, Louis Chowb. New therapies in HER2-positive breast cancer: A major step towards a cure of the disease? Cancer Treat Rev. 2012 Feb 2

Higgins MJ, Baselga J. Targeted therapies for breast cancer. J Clin Invest. 2011 Oct; 121(10):3797-803.

Additional Resources:

Breast-Cancer.net is a comprehensive web site with information specifically about breast cancer. It also has extensive references to other resources.

This article was originally published on 7/12/2014 and last revision and update of it was 9/14/2015.