Breast Diseases: Pathological processes of the BREAST.Fibrocystic Breast Disease: A common and benign breast disease characterized by varying degree of fibrocystic changes in the breast tissue. There are three major patterns of morphological changes, including FIBROSIS, formation of CYSTS, and proliferation of glandular tissue (adenosis). The fibrocystic breast has a dense irregular, lumpy, bumpy consistency.Breast: In humans, one of the paired regions in the anterior portion of the THORAX. The breasts consist of the MAMMARY GLANDS, the SKIN, the MUSCLES, the ADIPOSE TISSUE, and the CONNECTIVE TISSUES.Fibroadenoma: An adenoma containing fibrous tissue. It should be differentiated from ADENOFIBROMA which is a tumor composed of connective tissue (fibroma) containing glandular (adeno-) structures. (From Dorland, 27th ed)Breast Neoplasms: Tumors or cancer of the human BREAST.Adenofibroma: A benign neoplasm composed of glandular and fibrous tissues, with a relatively large proportion of glands. (Stedman, 25th ed)Carcinoma, Ductal, Breast: An invasive (infiltrating) CARCINOMA of the mammary ductal system (MAMMARY GLANDS) in the human BREAST.Mammography: Radiographic examination of the breast.Hyperplasia: An increase in the number of cells in a tissue or organ without tumor formation. It differs from HYPERTROPHY, which is an increase in bulk without an increase in the number of cells.Carcinoma, Intraductal, Noninfiltrating: A noninvasive (noninfiltrating) carcinoma of the breast characterized by a proliferation of malignant epithelial cells confined to the mammary ducts or lobules, without light-microscopy evidence of invasion through the basement membrane into the surrounding stroma.Breast Cyst: A fluid-filled closed cavity or sac that is lined by an EPITHELIUM and found in the BREAST. It may appear as a single large cyst in one breast, multifocal, or bilateral in FIBROCYSTIC BREAST DISEASE.Nipples: The conic organs which usually give outlet to milk from the mammary glands.Menopause: The last menstrual period. Permanent cessation of menses (MENSTRUATION) is usually defined after 6 to 12 months of AMENORRHEA in a woman over 45 years of age. In the United States, menopause generally occurs in women between 48 and 55 years of age.Carcinoma in Situ: A lesion with cytological characteristics associated with invasive carcinoma but the tumor cells are confined to the epithelium of origin, without invasion of the basement membrane.Precancerous Conditions: Pathological processes that tend eventually to become malignant. (From Dorland, 27th ed)Carcinoma, Lobular: A infiltrating (invasive) breast cancer, relatively uncommon, accounting for only 5%-10% of breast tumors in most series. It is often an area of ill-defined thickening in the breast, in contrast to the dominant lump characteristic of ductal carcinoma. It is typically composed of small cells in a linear arrangement with a tendency to grow around ducts and lobules. There is likelihood of axillary nodal involvement with metastasis to meningeal and serosal surfaces. (DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1205)Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Biopsy, Needle: Removal and examination of tissue obtained through a transdermal needle inserted into the specific region, organ, or tissue being analyzed.Biopsy: Removal and pathologic examination of specimens in the form of small pieces of tissue from the living body.Case-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Receptors, Estrogen: Cytoplasmic proteins that bind estrogens and migrate to the nucleus where they regulate DNA transcription. Evaluation of the state of estrogen receptors in breast cancer patients has become clinically important.Ultrasonography, Mammary: Use of ultrasound for imaging the breast. The most frequent application is the diagnosis of neoplasms of the female breast.Breast Feeding: The nursing of an infant at the breast.Palpation: Application of fingers with light pressure to the surface of the body to determine consistence of parts beneath in physical diagnosis; includes palpation for determining the outlines of organs.Mastitis: INFLAMMATION of the BREAST, or MAMMARY GLAND.Receptors, Progesterone: Specific proteins found in or on cells of progesterone target tissues that specifically combine with progesterone. The cytosol progesterone-receptor complex then associates with the nucleic acids to initiate protein synthesis. There are two kinds of progesterone receptors, A and B. Both are induced by estrogen and have short half-lives.Mastectomy: Surgical procedure to remove one or both breasts.Tumor Markers, Biological: Molecular products metabolized and secreted by neoplastic tissue and characterized biochemically in cells or body fluids. They are indicators of tumor stage and grade as well as useful for monitoring responses to treatment and predicting recurrence. Many chemical groups are represented including hormones, antigens, amino and nucleic acids, enzymes, polyamines, and specific cell membrane proteins and lipids.Neoplasm Invasiveness: Ability of neoplasms to infiltrate and actively destroy surrounding tissue.Age Factors: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.Risk: The probability that an event will occur. It encompasses a variety of measures of the probability of a generally unfavorable outcome.Postmenopause: The physiological period following the MENOPAUSE, the permanent cessation of the menstrual life.Estrogens: Compounds that interact with ESTROGEN RECEPTORS in target tissues to bring about the effects similar to those of ESTRADIOL. Estrogens stimulate the female reproductive organs, and the development of secondary female SEX CHARACTERISTICS. Estrogenic chemicals include natural, synthetic, steroidal, or non-steroidal compounds.Parity: The number of offspring a female has borne. It is contrasted with GRAVIDITY, which refers to the number of pregnancies, regardless of outcome.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Breast Neoplasms, Male: Any neoplasms of the male breast. These occur infrequently in males in developed countries, the incidence being about 1% of that in females.Menstruation: The periodic shedding of the ENDOMETRIUM and associated menstrual bleeding in the MENSTRUAL CYCLE of humans and primates. Menstruation is due to the decline in circulating PROGESTERONE, and occurs at the late LUTEAL PHASE when LUTEOLYSIS of the CORPUS LUTEUM takes place.Carcinoma: A malignant neoplasm made up of epithelial cells tending to infiltrate the surrounding tissues and give rise to metastases. It is a histological type of neoplasm but is often wrongly used as a synonym for "cancer." (From Dorland, 27th ed)Premenopause: The period before MENOPAUSE. In premenopausal women, the climacteric transition from full sexual maturity to cessation of ovarian cycle takes place between the age of late thirty and early fifty.Body Fluids: Liquid components of living organisms.Prognosis: A prediction of the probable outcome of a disease based on a individual's condition and the usual course of the disease as seen in similar situations.Menarche: The first MENSTRUAL CYCLE marked by the initiation of MENSTRUATION.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Neoplasm Metastasis: The transfer of a neoplasm from one organ or part of the body to another remote from the primary site.Cohort Studies: Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.Estrogen Replacement Therapy: The use of hormonal agents with estrogen-like activity in postmenopausal or other estrogen-deficient women to alleviate effects of hormone deficiency, such as vasomotor symptoms, DYSPAREUNIA, and progressive development of OSTEOPOROSIS. This may also include the use of progestational agents in combination therapy.Cell Line, Tumor: A cell line derived from cultured tumor cells.Breast Implants: Implants used to reconstruct and/or cosmetically enhance the female breast. They have an outer shell or envelope of silicone elastomer and are filled with either saline or silicone gel. The outer shell may be either smooth or textured.Odds Ratio: The ratio of two odds. The exposure-odds ratio for case control data is the ratio of the odds in favor of exposure among cases to the odds in favor of exposure among noncases. The disease-odds ratio for a cohort or cross section is the ratio of the odds in favor of disease among the exposed to the odds in favor of disease among the unexposed. The prevalence-odds ratio refers to an odds ratio derived cross-sectionally from studies of prevalent cases.Cathepsin D: An intracellular proteinase found in a variety of tissue. It has specificity similar to but narrower than that of pepsin A. The enzyme is involved in catabolism of cartilage and connective tissue. EC 220.127.116.11. (Formerly EC 18.104.22.168).Receptor, erbB-2: A cell surface protein-tyrosine kinase receptor that is overexpressed in a variety of ADENOCARCINOMAS. It has extensive homology to and heterodimerizes with the EGF RECEPTOR, the ERBB-3 RECEPTOR, and the ERBB-4 RECEPTOR. Activation of the erbB-2 receptor occurs through heterodimer formation with a ligand-bound erbB receptor family member.Lymphatic Metastasis: Transfer of a neoplasm from its primary site to lymph nodes or to distant parts of the body by way of the lymphatic system.Risk Assessment: The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)Breast Self-Examination: The inspection of one's breasts, usually for signs of disease, especially neoplastic disease.Proportional Hazards Models: Statistical models used in survival analysis that assert that the effect of the study factors on the hazard rate in the study population is multiplicative and does not change over time.Neoplasm Staging: Methods which attempt to express in replicable terms the extent of the neoplasm in the patient.Sensitivity and Specificity: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)Neoplasm Proteins: Proteins whose abnormal expression (gain or loss) are associated with the development, growth, or progression of NEOPLASMS. Some neoplasm proteins are tumor antigens (ANTIGENS, NEOPLASM), i.e. they induce an immune reaction to their tumor. Many neoplasm proteins have been characterized and are used as tumor markers (BIOMARKERS, TUMOR) when they are detectable in cells and body fluids as monitors for the presence or growth of tumors. Abnormal expression of ONCOGENE PROTEINS is involved in neoplastic transformation, whereas the loss of expression of TUMOR SUPPRESSOR PROTEINS is involved with the loss of growth control and progression of the neoplasm.Incidence: The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Tamoxifen: One of the SELECTIVE ESTROGEN RECEPTOR MODULATORS with tissue-specific activities. Tamoxifen acts as an anti-estrogen (inhibiting agent) in the mammary tissue, but as an estrogen (stimulating agent) in cholesterol metabolism, bone density, and cell proliferation in the ENDOMETRIUM.Progestins: Compounds that interact with PROGESTERONE RECEPTORS in target tissues to bring about the effects similar to those of PROGESTERONE. Primary actions of progestins, including natural and synthetic steroids, are on the UTERUS and the MAMMARY GLAND in preparation for and in maintenance of PREGNANCY.Mass Screening: Organized periodic procedures performed on large groups of people for the purpose of detecting disease.Confidence Intervals: A range of values for a variable of interest, e.g., a rate, constructed so that this range has a specified probability of including the true value of the variable.Outpatient Clinics, Hospital: Organized services in a hospital which provide medical care on an outpatient basis.Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.