Glossary


Absolute risk

—a measure of risk over time in a group of individuals; may be used to measure lifetime risk or risk over a shorter time period.

Accuracy

—the degree to which a test measures the true value of the attribute it is testing.

Adjuvant therapy

—the use of another form of therapy in addition to the primary surgical therapy. It usually refers to hormonal therapy, chemotherapy, or radiation.

Allele

—any one of a series of two or more different genes that occupy the same position (locus) on a chromosome.

Amplification

—a process by which genetic material is increased.

Analytical validity

—the accuracy of a test in detecting the specific characteristics that it was designed to detect, often measured by sensitivity and specificity. However, this accuracy does not imply any clinical significance, such as diagnosis.

Angiogenesis

—the formation of new blood vessels.

Antigen

—a substance that induces the immune system to produce antibodies that interact specifically with it.

Atypical hyperplasia

—proliferation of cells showing atypical nuclear form, especially as scattered cells.

Autosomal

—a non-sex-linked form of inheritance (the gene is not found on the X or Y chromosome).


Bias

—in general, any factor that distorts the true nature of an event or observation. In clinical investigations, a bias is any systematic factor other than the intervention of interest that affects the magnitude of



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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis Glossary Absolute risk —a measure of risk over time in a group of individuals; may be used to measure lifetime risk or risk over a shorter time period. Accuracy —the degree to which a test measures the true value of the attribute it is testing. Adjuvant therapy —the use of another form of therapy in addition to the primary surgical therapy. It usually refers to hormonal therapy, chemotherapy, or radiation. Allele —any one of a series of two or more different genes that occupy the same position (locus) on a chromosome. Amplification —a process by which genetic material is increased. Analytical validity —the accuracy of a test in detecting the specific characteristics that it was designed to detect, often measured by sensitivity and specificity. However, this accuracy does not imply any clinical significance, such as diagnosis. Angiogenesis —the formation of new blood vessels. Antigen —a substance that induces the immune system to produce antibodies that interact specifically with it. Atypical hyperplasia —proliferation of cells showing atypical nuclear form, especially as scattered cells. Autosomal —a non-sex-linked form of inheritance (the gene is not found on the X or Y chromosome). Bias —in general, any factor that distorts the true nature of an event or observation. In clinical investigations, a bias is any systematic factor other than the intervention of interest that affects the magnitude of

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis (i.e., tends to increase or decrease) an observed difference in the outcomes of a treatment group and a control group. Bioinformatics —use of computers and specialized software to organize and analyze biological information and data. Biomarker —A substance sometimes found in the blood, other body fluids, or tissues. A high level of biomarker may mean that a certain type of cancer is in the body. Examples of biomarkers include CA 125 (ovarian cancer), CA 15-3 (breast cancer), CEA (ovarian, lung, breast, pancreatic, and gastrointestinal tract cancers), and PSA (prostate cancer). See also Tumor marker. Biopsy —refers to a procedure that involves obtaining a tissue specimen for microscopic analysis to establish a diagnosis; can be done surgically or with needles. Blind study —a study in which the identity and relevant characteristics of the study subjects are concealed from the investigators. BRCA1 —a gene located on the short arm of chromosome 17; when this gene is mutated, a woman is at greater risk of developing breast or ovarian cancer, or both, than women who do not have the mutation. BRCA2 —a gene located on chromosome 13; a germ-line mutation in this gene is associated with increased risk of breast cancer. Breast self-examination —monthly physical examination of the breasts with the intent of finding lumps that could be an early indication of cancer. Cancer —a general term for more than 100 diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread through the bloodstream and lymphatic system to other parts of the body. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the bloodstream. Lymphoma is cancer that begins in the cells of the immune system. Carcinogen —any substance or agent that produces or incites cancer. Carcinoma in situ —Cancer that involves only the cells in which it began and that has not spread to nearby tissues. Case-control study —a study that compares two groups of people—those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition (controls). Researchers study the medical and lifestyle histories of the people in each group to learn what factors may be associated with the disease or condition. For example, one group may have been exposed to a

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis particular substance that the other was not. Also called a retrospective study. Results from this type of study are generally less reliable than a well-designed randomized controlled clinical trial. Case report —a description of a single case, typically describing the manifestations, clinical course, and prognosis of that case. Case series —a descriptive, observational study of a series of cases, typically describing the manifestations, clinical course, and prognosis of a condition. Catheter —a tube passed through the body for evacuating or injecting fluids into body cavities. cDNA —complementary DNA synthesized by RNA-directed DNA polymerase using RNA as a template; may be used as a probe for the presence of a gene code. Cell culture —the growth of cells in vitro, generally for experimental purposes. Chemoprevention —the use of natural or laboratory-made substances to prevent cancer. Chemoprophylaxis —drug treatment designed to prevent future occurrences of disease. Chemotherapy —the treatment of disease by means of chemicals that have a specific toxic effect on the disease producing microorganisms (antibiotics) or that selectively destroy cancerous tissue (anticancer therapy). Chromosome —chromosomes carry the genes, the basic units of heredity. Humans have 23 pairs of chromosomes; one member of each pair is from the mother and the other is from the father. Each chromosome can contain hundreds or thousands of individual genes. Clinical breast examination —a physical examination of the breasts, performed by a health care provider, with the intent of finding lumps that could be an early indication of cancer. Clinical outcome —the end result of a medical intervention, such as survival or improved health. Clinical trial —a formal study carried out according to a prospectively defined protocol that is intended to discover or verify the safety and effectiveness of procedures or interventions in humans. The term may refer to a controlled or uncontrolled trial. Randomized controlled clinical trials are considered the gold standard for clinical evidence. Clinical utility —identifying the clinical and psychological benefits and risks of positive and negative results of a given technique. Clinical validity —the accuracy of a test in diagnosing or predicting risk for a disorder, often measured by sensitivity and specificity. Cohort study —an observational study in which outcomes in a group of patients that received an intervention are compared with outcomes in a

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis similar group, that is, the cohort, either contemporary or historical, of patients that did not receive the intervention. In an adjusted- (or matched-) cohort study, investigators identify (or make statistical adjustments to provide) a cohort group that has characteristics (e.g., age, gender, disease severity) that are as similar as possible to the group that experienced the intervention. Composition of matter patent —proprietary claim on an actual substance that is isolated and properly characterized (i.e., BRCA1 or 2 gene sequence). Computed tomography —a special radiographic technique that uses a computer to assimilate multiple x-ray images into a two-dimensional, cross-sectional image, which also can be reconstructed into a three-dimensional image. This can reveal many soft tissue structures not shown by conventional radiography. Computer-aided detection —use of sophisticated computer programs designed to recognize patterns in images and provide assistance to interpreters to detect the presence of disease. This approach has been used along with mammography for the detection of breast cancer. Confidence interval —a range within which an estimate is deemed to be close to the actual value being measured. In statistical measurements, estimates cannot be said to be exact matches, but, rather, are defined in terms of their probability of matching the value of the characteristic being measured. Confounding factors —factors for which data adjustment is needed because they are entangled with other factors related to the disease or condition of interest. Contralateral —originating in or affecting the opposite side of the body. Contrast agent —a substance that enhances the image produced by medical diagnostic equipment such as ultrasound, x-ray, magnetic resonance imaging, or nuclear medicine or an imaging-sensitive substance that is ingested or injected intravenously to enhance or increase contrast between anatomical structures. Controlled observational studies —An experiment or clinical trial that includes an experimental group and a comparison (control) group that are not blindly assigned into their respective groups. These studies included those that compare outcomes among those who do or do not receive screening, but in which the subjects are not blindly assigned to a specific group. Core-needle biopsy —procedure in which a hollow needle is used to remove small cylinders of tissue from a suspected cancer. Cost-benefit analysis —a comparison of alternative interventions in which costs and outcomes are quantified in common monetary units.

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis Cost-effectiveness analyses —methods for comparing the economic efficiencies of different therapies or programs that produce health outcomes. Cross-sectional comparison —an observational study in which both risk factor(s) and disease are ascertained at the same time. Cytogenetics —the study of cytology in relation to genetics. Cytological screening —examination of cells for changes indicative of a disease or risk of disease, for example, Papanicolaou test (Pap smear) for cervical cancer. Cytology —The study of cells using a microscope to examine the characteristics of formation, structure, and function of cells. Deoxyribonucleic acid —the genetic material of all cells and many viruses that is a polymer of nucleotides. The monomer consists of phosphorylated 2-deoxyribose N-glycosidically linked to one of four bases—adenine, cytosine, guanine, or thymine. The sequence of these bases encodes genetic information. Detection —identifying disease. Early detection means that the disease is found at an early stage, before it has grown large or spread to other sites. Diagnosis —definitive confirmation of a specific disease usually by imaging procedures and from the use of laboratory findings. Diagnostic mammography —x-ray-based breast imaging undertaken for the purpose of diagnosing an abnormality discovered by physical exam or screening mammography. Also known as problem solving mammography. Diagnostic testing —the evaluation of patients with signs or symptoms associated with a disease. Digital mammography —see full-field digital mammography. DNA —abbreviation for deoxyribonucleic acid. DNA holds genetic information for cell growth, division, and function. See also deoxyribonucleic acid. Dose-response —the relation between the dose of a drug or other chemical and the degree of response it produces, as measured by the percentage of the exposed population showing a defined effect. Dosimetry —measurement of the amount of x-rays and radioactivity absorbed. Duct —a hollow passage for gland secretions. In the breast, a passage through which milk passes from the lobule (which makes the milk) to the nipple. Ductal carcinoma in situ —a lesion in which there is proliferation of abnormal cells within the ducts of the breast, but no visible evidence of

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis invasion into the duct walls or surrounding tissues; sometimes referred to as “precancer” or “pre-invasive cancer.” Ductal lavage —a procedure in which a small catheter is inserted into the nipple and the breast ducts are flushed with fluid to collect breast cells. Effectiveness —the extent to which a specific test or intervention, when used under ordinary circumstances, does what it is intended to do. Efficacy —the extent to which a specific test or intervention produces a beneficial result under ideal conditions (e.g., in a clinical trial). Elastography —the measurement of the elastic properties of tissue. Electrical impedance imaging —a procedure by which images are generated by transmitting a low-voltage electrical signal through the tissue. Electrical potential measurements —compares altered electrical gradients on various locations on the breast to potentially help identify cancer. Electronic palpation —use of pressure sensors to quantitatively measure palpable features of the breast such as the hardness and size of lesions. Epidemiology —science concerned with defining and explaining the interrelationships of factors that determine disease frequency and distribution. Epigenetics —the study of changes producing phenotypic effects in which gene activity is altered without modifying the nucleotide sequence. Epithelial tissue —those cells that form the outer surface of the body and that line the body cavities and the principal tubes and passageways. They form the secreting portions of glands and their ducts and important parts of certain sense organs. The cells rest on a basement membrane and lie close to each other, with little intercellular material between them. Etiology —the study of the causes of a disease. Exon —the portions of the DNA sequence in a gene that specify the sequence of amino acids in a polypeptide chain, as well as the beginning and end of the coding sequence. False-negative result —a test result that incorrectly indicates that the abnormality or disease being investigated is not present when in fact it is present. False-positive result —a test result that indicates that the abnormality or disease being investigated is present when in fact it is not. Familial clusters —a disease occurring in a family more frequently than would be expected in random distribution; however, some clusters may be due to chance. Fine-needle aspiration —a procedure by which a thin needle is used to draw up (aspirate) cell samples for examination under a microscope.

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis Full-field digital mammography —similar to conventional mammography (film-screen mammography) except that a dedicated electronic detector system is used to computerize and display the x-ray information. Gel electrophoresis —a method for separating proteins or nucleic acid fragments that is carried out in a silica or acrylamide gel under the influence of an electric field. Gene —a functional unit of heredity made up of a sequence of nucleotides that occupies a specific place or locus on a chromosome. Genetic marker —a genetic change in cells that is indicative of cancer or malignant potential, or a piece of DNA that lies on a chromosome so close to a gene that the marker and the gene are inherited together. A marker is thus an identifiable heritable spot on a chromosome. A marker can be an expressed region of DNA (a gene) or a segment of DNA with no known coding function. Genome —an organism’s entire complement of DNA, which determines its genetic makeup. Genotype —the genetic constitution of an organism or cell, as distinct from its expressed features known as the phenotype. Germ-line mutation —an inherited mutation found in all cells in the body. Health Maintenance Organization (HMO) —organized system for providing comprehensive prepaid health care that has five basic attributes: (1) provides care in a defined geographic area; (2) provides or ensures delivery of an agreed-upon set of basic and supplemental health maintenance and treatment services; (3) provides care to a voluntarily enrolled group of persons; (4) requires their enrollees to use the services of designated providers; and (5) receives reimbursement through a predetermined, fixed, periodic prepayment made by the enrollee without regard to the degree of services provided. Heterogeneous —exhibiting variable characteristics. Heterozygosity —the state of having different alleles at a specific locus in the genome. High-throughput technology —any approach using robotics, automated machines, and computers to process many samples at once. Histology —the study of the microscopic structure of tissue. Hyperplasia —an increase in the number of cells in a tissue or organ, excluding tumor formation. Imaging agent —any substance administered to a patient for the purpose of producing or enhancing an image of the body; includes contrast agents used with medical imaging techniques such as radiography, computed tomography, ultrasonography, and magnetic resonance imaging, as well

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis as radiopharmaceuticals used with imaging procedures such as single-photon emission computed tomography (SPECT) and positron emission tomography (PET). Immunocytochemistry or immunohistochemistry —a laboratory test that uses antibodies to detect specific biochemical antigens in cells or tissue samples viewed under a microscope; can be used to help classify cancers. Immunology —the study of immunity to diseases. In situ —in position, localized. In breast cancer usually either ductal carcinoma is situ (DCIS) or lobular carcinoma in situ (LCIS), in which early cancer that has not spread to neighboring tissue. Incidence —the number of new cases of a disease that occur in the population per unit of time. Infiltrating ductal carcinoma —breast cancer that has spread out of the breast ducts. See also invasive ductal carcinoma. Inflammatory breast cancer —A type of breast cancer in which the breast looks red and swollen and feels warm. The skin of the breast may also show the pitted appearance called peau d’orange (like the skin of an orange). The redness and warmth occur because the cancer cells block the lymph vessels in the skin. Intermediate outcomes —findings that are not health outcomes in themselves (e.g., cellular atypia) but that precede or may increase the risk of such outcomes. Invasive cancer —cancers capable of growing beyond their site of origin and invading neighboring tissue. Invasive ductal carcinoma —a cancer that starts in the ducts of the breast and then breaks through the duct wall, where it invades the surrounding tissue; it is the most common type of breast cancer, and accounts for about 80 percent of breast malignancies, also known as infiltrating ductal carcinoma. Invasive lobular carcinoma —a cancer that starts in the milk-producing glands (lobules) of the breast and then breaks through the lobule walls to involve the surrounding tissue; accounts for about 15 percent of invasive breast cancers. Lead-time bias —overestimation of survival time because of the backward shift in the starting point for the measurement of survival as a result of early detection. Length bias —overestimation of survival benefit due to the detection of slowly growing lesions by screening tests, perhaps including lesions that will never cause mortality. Lesion —an abnormal change in structure of an organ or other body part due to injury or disease; especially one that is circumscribed and well defined.

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis Lifetime probability —the probability of being diagnosed with a specified cancer during an entire lifetime of a certain amount of years. Linkage analysis —study aimed at establishing linkage between genes by analyzing the tendency for two or more nonallelic genes to be inherited together, because they are located more or less closely on the same chromosome. Lobular —of or pertaining to the lobes of an organ, such as the liver, lung, breast, thyroid, or brain. Lobular carcinoma in situ —abnormal cells within a breast lobule that have not invaded surrounding tissue. Not cancer per se, but can serve as a marker of future cancer risk. Localized cancer —a cancer that is confined to the place where it started; that is, it has not spread to distant parts of the body. Loss of heterozygosity (LOH) —loss of one allele at a specific genetic locus, usually accompanied by a point mutation in the remaining allele. Magnetic resonance imaging (MRI) —method by which images are created by recording signals generated from the excitation (the gain and loss of energy) of elements such as the hydrogen of water in tissue when placed within a powerful magnetic field and pulsed with radio frequencies. Magnetic resonance spectroscopy (MRS) —A noninvasive imaging method that provides information about cellular activity (metabolic information). Can also be used along with magnetic resonance imaging (MRI) which provides information about the shape and size of the tumor (spatial information). Also called magnetic resonance spectroscopic imaging and proton magnetic resonance spectroscopic imaging. Malignant —a tumor that has the potential to become lethal through destructive growth or by having the ability to invade surrounding tissue and metastasize. Malignant transformation —changes that a cell undergoes as it develops the ability to form a malignant tumor. Mammogram —x-ray image of the breast. Mammography —the practice of imaging breast tissue with x-rays for screening or diagnostic purposes in detecting or diagnosing cancer. Mass spectroscopy —a method for separating ionized molecular particles according to mass by applying a combination of electrical and magnetic fields to deflect ions passing in a beam through the instrument. Medicaid —federal- and state-funded health insurance program for certain low-income people. It covers approximately 36 million individuals including children; aged, blind, and/or disabled people; and people who are eligible to receive federally assisted income maintenance payments.

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis Medicare —a program that provides health insurance to people age 65 and over, those who have permanent kidney failure, and people with certain disabilities. Menarche —onset of menstruation at puberty. Menopause —permanent cessation of menstrual activity. Messenger RNA —the molecule, also called mRNA, that carries the information from the DNA genetic code to areas in the cytoplasm of the cell that make proteins. Meta-analysis —systematic methods that use statistical techniques for combining results from different studies to obtain a quantitative estimate of the overall effect of a particular intervention or variable on a defined outcome. This combination may produce a stronger conclusion than can be provided by any individual study (also known as data synthesis or quantitative overview). Metaplasia —the change in the type of adult cells in a tissue to a form that is not normal for that tissue. Metastasis —the ability of cancer cells to move from one part of the body to another, resulting in the growth of a secondary malignancy in a new location. Method-of-use patent —proprietary claim on the specific use of a characterized substance or invention (i.e., the genetic test for mutation). Methylation —the attachment of a methyl group (CH3) to cytosine residues of eukaryotic DNA to form 5-methylcytosine. Microarray —thousands of different oligonucleotides spotted onto specific locations on glass microscope slides or silicon chips, which are then hybridized with labeled sample DNA or RNA. Microcalcifications —tiny calcium deposits within the breast, singly or in clusters; often found by mammography. They may be a sign of cancer. Microsatellite(s) —stretches of DNA consisting of short, repeated sequences showing a higher spontaneous mutation rate than coding DNA, which makes them useful markers for DNA stability. Modality —method of application or use of any therapy or medical device. Molecular epidemiology —a science that focuses on the contribution of potential genetic and environmental risk factors, identified at the molecular level, to the etiology, distribution, and prevention of disease within families and across populations. Molecular markers —changes in cells, at the molecular level, that are indicative of cancer or malignant potential. Monoenergetic x-rays —a beam of x-rays whose photon energy is found to lie within a very narrow band. Currently, these types of x-rays can only be produced at a synchrotron. Morbidity —a diseased condition or state; the incidence of a disease or of all diseases in a population.

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis Morphology —science of structure and form without regard to function. Mortality rate —the death rate; expresses the number of deaths in a unit of population within a prescribed time and may be expressed as crude death rates or as death rates specific for diseases and, sometimes, for age, sex, or other attributes. Mutation —a change either in the nucleotide sequence of DNA or in the order, number, or placement of genes on or across chromosomes that may result in a change in the structure or function of a protein and possibly the lack of expression of a protein altogether. Neoplasm —An abnormal mass of tissue that results from excessive cell division. Neoplasms may be benign (not cancerous), or malignant (cancerous). Also called tumor. Nipple aspiration —use of suction to collect breast fluid through the nipple of nonlactating women. Observational studies —A type of study in which individuals are observed or certain outcomes are measured. No attempt is made to affect the outcome (for example, no treatment is given). Occult tumors —undetected and without symptoms. Odds ratio —a comparison of the presence of a risk factor for disease in a sample of diseased subjects and nondiseased controls. Oligonucleotide —a small DNA or RNA molecule composed of a few nucleotide bases. Oncology —branch of medicine dealing with the treatment of cancer. Optical imaging —use of light, usually in the near-infrared range, to produce an image of tissue. p value —the probability that an outcome as large as or larger than that observed would occur in a properly designed, executed, and analyzed analytical study if in reality there was no difference between the groups; often used to define statistical significance of results. p53 —a tumor suppressor gene commonly mutated in cancer. Paget’s disease of the nipple —A form of breast cancer in which the tumor grows from ducts beneath the nipple onto the surface of the nipple. Symptoms commonly include itching and burning and an eczema-like condition around the nipple, sometimes accompanied by oozing or bleeding. Palpable tumor —a tumor that can be felt during a physical examination. Pap smear —a cytological test developed by George N. Papanicolaou for the detection of cervical cancer. Penetrance —the proportion of individuals with a specific genotype who express the associated characteristic in the phenotype.

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis Phenotype —the physical characteristics or makeup of an individual. Photonics —the technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The science includes light emission, transmission, deflection, amplification, and detection by optical components and instruments, lasers and other light sources, fiber optics, electro-optical instrumentation, related hardware and electronics, and sophisticated systems. Polymerase chain reaction —a process for amplifying a DNA molecule from 106 to 109 fold. Polymorphism —the regular and simultaneous occurrence in a population of two or more alleles of a gene in which the frequency of the rarer of the alleles is greater than can be explained by recurrent mutation alone. Positional cloning —cloning a gene simply on the basis of knowing its position in the genome without any idea of the function of that gene. Positive predictive value —a measure of accuracy for a screening or diagnostic test; indicates what portion of those with an abnormal test result actually have the disease; formula (PPV = TP/ TP + FP). Positron emission tomography —use of radioactive tracers such as labeled glucose to identify regions in the body with altered metabolic activity. Premalignant —changes in cells that may, but that do not always, become cancer. Also called “precancer.” Prevalence —the number of cases of disease, infected persons, or persons with some other attribute, present at a particular time and in relation to the size of the population from which they are drawn. Primary cancer prevention —prevention the development of cancer. Prognosis —prediction of the course and end of disease and the estimate of chance for recovery. Progression —the growth or advancement of cancer, indicating a worsening of the disease. Prophylactic bilateral mastectomy —surgical removal of both breasts with the intent of reducing the risk of developing breast cancer later in life. Prophylaxis —the prevention of disease, preventive treatment. Proprietary rights —exclusive rights held by a private individual or corporation under a trademark or patent. Prostate-specific antigen (PSA) testing —used to screen for cancer of the prostate and to monitor treatment by measuring the amount of PSA in the blood. PSA is a protein produced in the bloodstream. Proteome —all of the proteins produced by a given species, just as the genome is the totality of the DNA possessed by that species. Proto-oncogene —A normal gene which, when altered by mutation, becomes an oncogene that can contribute to cancer. The defective versions of proto-oncogenes, known as oncogenes, can cause a cell to divide in an

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis unregulated manner. This growth can occur in the absence of normal growth signals such as those provided by growth factors. Randomization —a method that uses chance to assign participants to comparison groups in a trial by using a random-numbers table or a computer-generated random sequence. Random allocation implies that each individual being entered into a trial has the same chance of receiving each of the possible interventions. Randomized controlled trial —a true prospective experiment in which investigators randomly assign an eligible sample of patients to one or more treatment groups and a control group and follow patients’ outcomes (also known as randomized clinical trial). This is the gold standard for evidence in a clinical trial. Relative risk —compares the risk of disease among people with a particular risk factor to the risk among people without that risk factor. If the relative risk is above 1.0, then risk is higher among those with the risk factor than those without. Relative risks below 1.0 reflect an inverse association between a risk factor and the disease, that is, a protective effect, or lower risk, associated with the exposure. Reliability —the consistency of the result when a test is repeated. Also known as reproducibility. Risk —a quantitative measure of the probability of developing or dying from a particular disease such as cancer. Scintimammography —use of radioactive tracers to produce an image of the breast. Screen-film mammography —conventional mammography in which the x-rays are recorded on film. Screening —systematic testing of an asymptomatic population to determine the presence of a particular disease. Screening mammography —x-ray-based breast imaging in an asymptomatic population used to detect breast cancers at an early stage. Secondary cancer —cancer that has spread from the site where it first appeared to another site. Sensitivity —a measure of how often a test correctly identifies women with breast cancer. Calculated as the number of true-positive results divided by the number of true-positive results plus the number of false-negative results; formula (Se = TP/[TP + FN]). Signal transduction —the biochemical events that conduct the signal of a hormone growth factor from the cell exterior, through the cell membrane, and into the cytoplasm. This involves a number of molecules, including receptors, proteins, and messengers. Soft copy —image display on a computer screen rather than on film.

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis Somatic mutation —an alteration in DNA that occurs after conception. Somatic mutations can occur in any of the cells of the body except the germ cells (sperm and egg) and therefore are not passed on to children. These alterations can (but do not always) cause cancer or other diseases. Sonography —a technique in which high-frequency sound waves are bounced off internal organs and the echo pattern is converted into a two-dimensional picture of the structures beneath the transducer. See also Ultrasound. Specificity —the proportion of persons without disease who correctly test negative; formula (Sp = TN/[TN +FP]). Specimen bank —stored patient tissue samples that are used for biomedical research (also tumor or tissue banks). Spectroscopy —analytical use of an instrument that separates radiant energy into its component frequencies or wavelengths by means of a prism or grating to form a spectrum for inspection. Spiral computed tomography —a detailed cross-sectional picture of areas inside the body. The images are created by a computer linked to an x-ray machine that scans the body in a spiral path. Also called helical computed tomography. Squamous cell carcinoma —a malignant growth originating from a squamous cell. This form of cancer can be seen on the skin, lips, and inside the mouth, throat, or esophagus. Statistical power —the likelihood that a study will find a particular effect if the effect exists; usually varies with sample size and other factors. Stereotactic breast biopsy —use of breast images (x-ray or ultrasound) taken at various angles to generate a three-dimensional image for plotting the exact position of the suspicious lesion and for guiding the placement of a biopsy needle. Surrogate endpoints —short-term, intermediate endpoints in a clinical study that are thought to be representative or predictive of longer-term outcomes. Surveillance —close and continuous observation, screening, and testing of those at risk for a disease. Survival —average period of time from diagnosis to death. Systemic therapy —treatment involving the whole body, usually using drugs. Telemammography —the process of satellite or long-distance transmission of digital mammography for consultation. Thermography —use of a device that detects and records the heat produced by tissues to generate an image. Thermotherapy —use of lasers or high-intensity ultrasound to heat and destroy tumor cells.

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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis Tissue array —small cylinders of tissue punched from 1,000 individual tumor biopsy specimens embedded in paraffin. These cylinders are then arrayed in a large paraffin block, from which 200 consecutive tissue sections can be cut, allowing rapid analysis of multiple arrayed samples by immunohistochemistry or in situ hybridization. Tomography —any of several techniques for making x-ray pictures of a predetermined plane section of a solid object by blurring out the images of other planes. Tomosynthesis —a variation of tomography in which several radiographs of a patient are taken at different angles, and back-projection of the resulting images produces a light distribution in a chosen three-dimensional volume of space that replicates the same volume in the patient. Transcription —synthesis of RNA by an enzyme called RNA polymerase that uses a DNA template; the first step in protein biosynthesis. Transcriptome —the complete collection of transcribed elements of the genome. In addition to mRNAs, it also represents noncoding RNAs which are used for structural and regulatory purposes. Alterations in the structure or levels of expression of any one of these RNAs or their proteins can contribute to disease. Translational research —the research needed to move the fruits of basic research into clinical practice. Tumor —an abnormal mass of tissue that results from excessive cell division that is uncontrolled and progressive, also called a neoplasm. Tumors perform no useful body function. They may be either benign (not cancerous) or malignant. Tumor marker —any substance or characteristic that indicates the presence of a malignancy. Tumor suppressor genes —genes that slow cell division or that cause cells to die at the appropriate time. Mutations in these genes can lead to uncontrolled cell growth and the development of cancer. Tumorigenesis —the induction of the malignant growth of abnormal cells. Ultrasound —use of inaudible, high-frequency sound waves to create an image of the body. Venipuncture —the puncture of a vein (usually in the arm) with a hollow bore needle for the purpose of obtaining a blood specimen. X-ray —a type of ionizing radiation used for imaging purposes that uses energy beams of very short wavelengths (0.1 to 1000 angstroms) that can penetrate most substances except heavy metals.