risk of carcinoma if atypical cells are present).
Some benign breast tumors include fibroadenoma, intraductal papilloma, and phyllodes tumor. Fibroadenoma is a small, mobile, firm mass that occurs in patients less than 25 years of age. Fibroadenomas increase in size and tenderness with increased estrogen (such as during menstruation or pregnancy). This type of mass is not a precursor to cancer. Intraductal papillomas are small tumors that grow in the lactiferous ducts, often beneath the areola. These present with serous or bloody discharge and are associated with a slightly increased risk of carcinoma. Phyllodes tumor, which may become malignant, is a large tumor of connective tissue and cysts that presents in postmenopausal women.
Diagnosis and Treatment
Breast cancer can be tested in many ways, including determination of whether the cancer cells are stimulated by the presence of the hormones. This type of exam measures a person’s hormone receptor (HR) status and tests for a positive or negative result which, respectively, corresponds to stimulation or lack of the cancer cell. The test uses the hormones estrogen and progesterone to test a tumor for cancer. If the test is positive for either estrogen or both estrogen and progesterone, then hormone therapy is usually the course of action for the treatment of the cancer in lieu of more intensive treatments. Hormone therapy can also be advantageous because it can help prevent the recurrence of cancer in both the breast and other parts of the body.
Another way of determining whether or not a tumor is malignant is by testing for the amount of protein in the tumor. The human epidermal growth factor receptor 2 (HER-2/neu) test can detect if there is an abnormally high amount of protein in the tumor. During the HER-2 exam, physicians use oncogene measurements to measure how quickly the cells in the tumor are growing. A positive HER-2 result indicates a higher-than-normal growth rate, which is indicative of either abnormally high levels of protein in the cancer cells or overexpression of the HER-2 gene, which causes too much protein to be produced. The treatment of tumors that test positive for the HER-2 exam utilize therapies that specifically target the HER-2 gene to reduce the amount of protein being produced, thus slowing the growth rate of the tumor.
The course of action for a cancer ultimately depends on the progression of the cancer. On a scale of I–IV, cancers in stages I–III are often treatable and the focus turns toward curing the patient of the cancer. In these stages, treatment involves a lumpectomy, the removal of a lump or small part of the breast, or a quadrantectomy, the removal of a quarter part of the breast in addition to other therapies. In the more advanced types of stage IV cancers, however, the focus turns from attempting to cure the cancer to improving the quality of life and increasing their chances of a longer survival. Treatment of stage IV cancer often leads to the patient receiving mastectomy (removal of the whole breast), in combination with chemotherapy, radiation therapy, and/or hormone therapy.
Krishna S. Vyas
University of Kentucky College of Medicine
Arthur Lemons III
Walisha Bland-Lemons
University of Kentucky
See Also: Breast: Cell Types Composing the Tissue; Breast: Development and Regeneration Potential; Breast: Existing or Potential Regenerative Medicine Strategies.
Further Readings
Atkins, Kristen and Christina Kong. Practical Breast Pathology: A Diagnostic Approach. Philadelphia: Elsevier Saunders, 2013.
Breast Cancer Care. “Sclerosing Lesions of the Breast.” Breast Cancer Care: The Breast Cancer Support Charity (February 21, 2013).
“Breast Pathology.” John Hopkins Medicine (n.d.) http://www.hopkinsmedicine.org/avon_foundation_breast_center/treatments_services/breast_cancer_diagnosis/breast_pathology/ (Accessed May 2014).
Chen, Yi-Bin. “Breast Cancer.” Medline Plus: Trusted Health Information for You (November 17, 2012).
Filton, Mike. “Cancer and Natural Selection.” Journal of the National Cancer Institute, v.104/23 (2012).
Frank, Steven A. Dynamics of Cancer: Incidence, Inheritance, and Evolution. New Jersey: Princeton University Press, 2007.
Gabriel, Allen and Patrick Maxwell. “Breast Anatomy.” Medscape (April 9, 2013).
Harris, Jay, Marc Lippman, Kent Osborne, et al. Diseases of the Breast (4th ed.). Philadelphia: Lippincott Williams & Wilkins, 2010.
Breast: Stem and Progenitor Cells in Adults
Breast: Stem and Progenitor Cells in Adults
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Breast: Stem and Progenitor Cells in Adults
The mammalian breast is one of the few organs in the female body that undergoes large changes during the life cycle. Puberty, pregnancy, and lactation are some of the physiological processes that dramatically alter the nature and cellular composition of the breast. This article discusses the stem and progenitor cell populations present in the breast that allow for this inherent regenerative capacity in the breast.
The breast has a branched network of ducts and lobules that comprises the glandular tissue responsible for producing milk during lactation. It is also comprised of a layer of myoepithelial cells that have muscle-like contractile ability that can contract to allow for milk extraction from the mammary glands into the ducts that carry the milk. In essence, there are three major cell types in the glands and ducts of the breast. The luminal, or outward-facing alveolar cells, and the layer of myoepithelial cells that form a basal layer below the alveolar cells make up the glandular portion. The ductal cells line the epithelial layer of the ducts. These cells arise from two lineages, the luminal and myoepithelial. The alveolar and ductal cells described above arise from the luminal lineage. These three cell types are thought to originate from a common progenitor stem cell. Several other cell types exist in the breast, including a large amount of adipose cells that make up the fat pads in the breast and stromal cells in the connective tissue of the breast. Stem and progenitor cells in the breast, which are the focus of this article, are predominantly present to the glands where myoepithelial and alveolar cells are present. In particular, the major population of multipotent stem cells discovered in the breast is restricted to the basal layer of the glands.
During puberty, cell growth causes the branching and elongation of the epithelial ducts. After puberty, cycles of both proliferation and differentiation occur, with the estrous cycle accounting for the growth and decay of the alveolar tissue.
During pregnancy, the breast undergoes extensive changes, with a dramatic increase in the glands and ducts to allow for milk production in the lactating period. After lactation, the glands undergo involution as a result of cell death and return to their prepregnant state. The ability of the breast cell types to proliferate, involute, and proliferate again with each pregnancy presented the first clues for the presence of a stem cell type in the breast that can serve as the origin of the epithelial cell types.
Evidence that pointed toward the presence of mammary stem or progenitor cells with regenerative capacity in the breast came from transplantation experiments
