(114) Definition
adhesion Adhesions are an internal growth of scar tissue that may occur following abdominal surgery, sometimes causing pain or intestinal blockage. See linkhere
adjuvant In the context of cancer drug therapy, adjuvant refers to drug therapy employed after the primary tumor has been surgically resected. With respect to Gleevec, there are clinical trials underway to evaluate “adjuvant Gleevec.” In these trials patients are treated with Gleevec for a given time period (such as one or two years) after resection of the primary tumor, in order to determine whether this course of Gleevec will prevent later recurrence or metastasis after the drug is discontinued.
allele An allele is an alternative form of the same gene that occupies a particular locus (position) on a chromosome. Different alleles produce variation in inherited characteristics such as hair color or blood type Often one allele is “dominant” and the other is “recessive.” The “dominant” allele will determine what trait is expressed. When one allele is lost the result is “loss of heterozygosity.”
Ampulla of Vater This is the opening of the ducts from the gall bladder and pancreas into the duodenum, also called the pancreaduodenal ampulla. It becomes important in GIST if this section of the duodenum must be removed, since then the patient would lose the digestive benefit of bile from the gallbladder and pancreatic enzyme secretions.
anastomosis The surgical formation of a passageway between any two spaces or hollow organs in the body. For example, if a GIST patient had surgery performing a total gastrectomy, then the anastomosis would join the esophagus to the duodenum.
anemia A condition in which there are not enough healthy red blood cells to deliver adequate oxygen to the body, usually measured by a decrease in the amount of hemoglobin. Hemoglobin Illustration: linkhere Some symptoms include weakness, pale skin, rapid heartbeat, shortness of breath, dizziness, headache, numbness or coldness in extremities. There are several causes of anemia such as vitamin deficiency and kidney failure to name a few. Certain chronic diseases such as cancer can also cause anemia by interfering with the production of red blood cells. A hormone called erythropoietin, which is produced by the kidneys, stimulates bone marrow to produce red blood cells. With GIST, a shortage of this important hormone can be a side effect of chemotherapy such as Gleevec or Sutent. Treatment with injections of drugs such as Procrit or Aranesp can stimulate the bone marrow to produce the needed red blood cells.
aneuploidy Aneuploidy is a state where abnormal numbers of specific chromosomes exist within the nucleus. Human somatic cells (other than egg or sperm) are diploid, having both maternally and paternally inherited copies of the basic chromosomes. Monosomy, as a kind of aneuploidy, is the loss of one copy of a chromosome from a cell nucleus. Trisomy is the presence of three copies of a particular chromosome, instead of the normal pair. Aneuploidy is common in cancerous cells with occurrence of either fewer or more than the correct two copies of a specific chromosome. Aneuploidy in cancer is due to the accumulation of mutations that cause instabilities and imbalances in the segregation of duplicated chromosomes into the each of the identical daughter cells formed during cell division.
angiogenesis The process of development of new blood vessels. With respect to tumors, angiogenesis is required in order for the tumor to grow beyond a small size. Some anti-cancer drugs target angiogenesis.
antigen An antigen is a molecule that is recognized by the immune system and stimulates the production of antibodies. Usually an antigen is a protein or polysaccharide, but it can be any type of molecule. The introduction of foreign (exogenous) antigens into the body can trigger an immune response. Endogenous antigens are antigens that have been generated within the cell as a result of normal cell metabolism or viral infection. Degradation fragments of endogenous antigens are presented on class I MHC molecules on the cell surface. Tumor antigens are endogenous antigens presented by class I MHC molecules on the surface of tumor cells. These antigens are sometimes presented exclusively by tumor cells and not normal cells. In this case, they are called tumor-specific antigens. Mutated proteins unique to the tumor cells are one type of tumor-specific antigen. More common are antigens that are highly correlated with tumor cells, but are also found to a lesser extent on normal cells. These are called tumor-associated antigens. Cytotoxic T Lymphocytes that recognize tumor antigens may be able to destroy the tumor cells.
anus The posterior opening of the alimentary canal. The opening at the end of the digestive tract where stool leaves the body. The anus is formed partly from the surface layers of the body, including skin, and partly from the intestine. Anus Illustration:linkhere
apoptosis A genetically determined process of cell self-destruction, often described as “programmed cell death.” In adults it is activated either by the presence of an abnormality or by the removal of a stimulus or suppressing agent. This is a normal physiological process eliminating DNA-damaged, superfluous or unwanted cells. Disruption of apoptosis may result in uncontrolled cell growth and tumor formation. Cancer cells evade apoptosis, thereby becoming immortal and proliferating out of control.
ascites Abnormal accumulation of excess fluid in the space between the membranes lining the abdomen and abdominal organs (the peritoneal cavity).
benign Any condition which, untreated or with symptomatic therapy, will not become life-threatening. Benign tumors are not cancerous and do not invade surrounding tissues and do not spread (metastasize) to other parts of the body. Some benign tumors can, due to mass effect, cause life-threatening complications. Tumors may be benign but at risk for degeneration into malignancy. These are termed “premalignant”.
Billroth Two different types of partial gastrectomy (partial stomach removal) operations are called billroth I and billroth II. Here is a link showing diagrams of these surgeries. linkhere
biopsy A diagnostic procedure in which a small amount of tissue or fluid is removed for examination under a microscope and testing by a pathologist to determine its characteristics and diagnose any disease present. In GIST this is a sample of tumor tissue and the pathologist tests it for cell markers including KIT to determine whether it is GIST or a different tumor type. Needle biopsies performed through the skin (percutaneous biopsies) or open biopsies through an incision are generally not recommended in GIST due to the possibility of spreading tumor cells. Please link to the Ask the Professional section of our website for a discussion of GIST biopsies by Dr. Christopher Corless http://www.gistsupport.org/needlebi opsy.html
c-kit This is the gene that encodes for (gives the DNA blueprint for production of) the KIT protein that is the growth factor receptor. GIST usually arises from an error in the structure of the KIT protein on some interstitial cells of Cajal because of a mutation in the c-kit gene controlling the formation of the KIT protein.
cafe au lait spots Typically medium-brown pigmented skin spots that develop on the chest, back, pelvis, elbows and knees. These spots may exist at birth or appear during infancy. People affected by neurofibromatosis 1 gene deficiency usually have these pigmented spots, but they also are found in people without NF1.
cancer Malignancy. A cancer is a group of cells, usually derived from a single cell, that has lost its normal control mechanisms and thus has unregulated growth. Cancer is caused by damage or mutations in DNA. DNA is like a set of instructions for cells, telling them how to grow and divide. When a mutation occurs in DNA, normal cells will repair the mutation or simply die. In cancer, the cells continue living with the mutation and, as a result, grow and divide in a chaotic fashion. Cancerous (malignant) cells can develop from any tissue within any organ. As cancerous cells grow and multiply they form a tumor that invades and destroys adjacent tissues and can metastasize to form new tumors in other parts of the body.
carcinoma A cancer (malignant tumor) in the epithelial (skin) tissues that cover the internal and external surfaces of the body, in contrast to sarcoma (a cancer in non-epithelial connective tissues).
CD (cluster of differentiation) Cluster of differentiation (CD) molecules are markers on the cell surface, as recognized by specific sets of antibodies, used to identify the cell type, stage of differentiation and activity of a cell.
CD117 (also known as KIT, Stem Cell Factor Receptor, and Steel Ligand Receptor). CD117 (KIT) is a transmembrane glycoprotein from the type III receptor tyrosine kinase family. KIT is the receptor for the growth factor Stem Cell Factor, also known as “steel factor” or “KIT ligand.” As a result of interaction with Stem Cell Factor, KIT initiates essential signal transduction pathways that transmit biological signals for cellular proliferation, survival, differentiation, and migration. KIT is expressed on almost all hematopoietic progenitor cells, melanocytes, mast cells, and interstitial cells of Cajal from the digestive tract. Aberrant expression or mutations of the c-kit gene is involved in the pathogenesis of several cancers, including GIST. KIT is structurally similar to the Platelet-Derived Growth Factor receptor (PDGFR).
CD34 CD34 is a transmembrane glycoprotein expressed on hematopoietic progenitor cells of all lineages as well as the most primitive pluripotential stem cells. CD34 antigen expression is highest on the most primitive stem cells and is gradually lost as lineage committed progenitors differentiate. The CD34 antigen is also present on capillary endothelial cells and on bone marrow stromal cells. The mucin-like structure of CD34 suggests a role in ceullar adhesion, possibly in adhesion of progenitors and stem cells to the stromal cells. About 70% of GISTs express CD34, including nearly all gastric GISTs but fewer intestinal GISTs.
chondroma A benign tumor containing the structural elements of cartilage. Chondromas in the lungs (pulmonary chondromas) are one of the tumor types in Carney Triad, along with GISTs (usually gastric) and paragangliomas.
clone With respect to GIST, a clone is a group of genetically identical cells descending from a single common cell within the tumor, therefore having the same mutation characteristics and same potential for drug resistance. Sometimes within a tumor that is under control with Gleevec a clone will appear that is resistant to the drug. This is sometimes called the “nodule within a mass” phenomenon.
codon A codon is a single unit in the genetic code, also called a triplet, a set of any three adjacent bases in the DNA (or RNA). It is made of a specific sequence of three consecutive nucleotides that specify a particular amino acid in a specific structural position in a polypeptide chain during the synthesis of a protein. Codons also serve as signals to start or stop protein synthesis. A single exon includes numerous codons. Overall, there are 43 = 64 different codon combinations. For example, the DNA sequence ATGGTTCAC contains the codons ATG, GTT and CTT, which respectively encode for the amino acids methonine, valine, and proline. So, this DNA sequence represents a protein sequence, three amino acids long. DNA is comprised of four types of bases, and so overall there are 43 = 64 different codon combinations. 61 specify the incorporation of an amino acid into a protein chain while the remaining three are stop codons that signal the end of a protein. The code is degenerate, meaning redundant: i.e. each amino acid has more than one codon.
CT or computerized tomography scan Also known as CAT scan (computer assisted tomography). A diagnostic procedure in which the x-ray source rotates around the patient so that an x-ray beam is sent through the patient from many different angles. The x-rays are read by a computer, which constructs three-dimensional images of the body. CT is a painless procedure. An injection of intravenous contrast is usually used to make the blood vessels show up better.
diploid Diploid cells contain two sets of chromosomes, inheriting a set of chromosomes from each the mother and the father. In human somatic (body) cells, a full complement of chromosomes is 46 (22 pairs of autosomes and two sex chromosomes). This number is naturally twice the haploid number of 23 chromosomes contained in human eggs (ova) and sperm. Most higher organisms are diploid. Plants may be polyploid, (carrying three or more copies of each chromosome).
duodenum The first, shortest and widest part of the small intestine that in humans is about 10 inches long. Located between the stomach and the jejunum, it extends from the pylorus to theundersurface of the liver where it descends for a variable distance and receives the bile and pancreatic ducts, then bends to the left and finally upward to join the jejunum near the second lumbar vertebra. After food combines with stomach acid they descend into the duodenum where they mix with bile from the gall bladder and digestive juices from the pancreas. Digestive System Illustration; linkhere
emesis Vomiting.
endophytic When applied to GIST, endophytic refers to a tumor growing into the lumen (food passageway) of the gastrointestinal tract.
endoscope A small, flexible tube-like instrument, with a light on the end of it and consisting of thousands of tiny glass fibers, to allow a doctor to see into the esophagus, stomach, duodenum, and colon. An endoscope also allows a doctor to perform biopsies, take color photographs, and perform certain medical procedures that would otherwise require surgery.
epithelium (adjective epithelial) The cells that line hollow organs and glands and which make up the outer surface of the body. Epithelial cells help to protect or enclose organs; some produce mucous or other secretions. Epithelial cells can be arranged in single layers or multiple layers depending on the type.
epitope An epitope is a surface portion of a foreign organism (or foreign bio-molecules) that elicits an immune response. For example, an epitope may be a specific site on a bacterial or viral protein that is recognized by the immune system as a foreign substance. Antibodies manufactured by B lymphocytes or cytotoxic T cells neutralize the epitope by physically combining with it. As biological molecules such as proteins and carbohydrates can be very large, each of them may contain many unique epitopes each of which is capable of eliciting an immune response.
esophagus The muscular “swallowing tube” that in adult humans is about nine inches (23 centimeters) long. It begins at the pharynx, goes down the neck between the trachea and the spinal column and behind the left bronchus where it pierces the diaphragm slightly to the left of the middle line and empties into the stomach. Also called the gullet.
exon An exon is a unit of genetic instructions for constructing a protein when a new cell is formed. Exons are found within cellular DNA and the RNA used to make new cells. Relevant to GIST, different exons on chromosome 4 code the formation of specific different parts of the KIT protein and the PDGFRA protein. Mutations in these exons cause incorrect construction of the corresponding parts of the protein, leading to cancer.
exophytic When applied to GIST, exophytic describes a tumor growing outward from the wall of the gastrointestinal tract toward the mesentery or abdominal cavity, not inward toward the lumen (food passageway).
fibroblast A common type cell found throughout the body, which secretes proteins and especially molecular collagen from which the extracelluar fibrillar matrix of connective tissue forms. From fiber, and blast- a formative unit of living matter: a bud, sprout, or germ.
fistula An abnormal opening between two internal organs or between an internal organ and the outside of the body or an internal body cavity. If a fistula develops after GI tract surgery, for example, then the affected part of the GI tract could leak its contents into the abdominal cavity.
gastrectomy A surgical procedure to remove all or part of the stomach. See partial gastrectomy under billroth and total gastrectomy under Roux-en-Y.
gastric Referring to the stomach.
gastrointestinal tract The series of digestive organs which starts with the mouth and includes the esophagus, stomach, duodenum, small intestine, large intestine, rectum and anus.
germline mutation A heritable change in the DNA that occurred in an egg or sperm (or the cells which give rise to eggs or sperm, called germ cells) or the zygote (fused egg-sperm) at the single-cell stage. When transmitted to a child, a germline mutation is incorporated in every cell of their body.
guaiac-positive stool Feces that have blood in them, as determined by a diagnostic test using a chemical reagent, the resin from the wood of a guajacum plant. Stool sample will turn blue when the resin is mixed with a stool specimen on test paper. Kits for measuring occult blood in the stools are now available at most drug stores.
hamartoma Benign, tumor-like but non-cancerous overgrowth of tissue that is disordered in structure.
hematemesis Vomiting of blood.
hematopoietic or hemapoietic Referring to or promoting the formation and development of blood cells.
hemorrhage Bleeding. Small hemorrhages are classified according to size as petechiae (very small), purpura (up to 1 cm), and ecchymoses (larger).
histology The study of cells and tissue on the microscopic level. Also called microscopic anatomy, it deals with the minute structure, composition, and function of the tissues.
hyperpigmentation Abnormally increased pigmentation in a body part or tissue (such as the skin).
hyperplasia An abnormal or unusual increase in the number of normal cells in normal arrangement in a tissue.
ileum The lowest section of the small intestine, connecting to the colon (large intestine).
immunohistochemical Relating to the staining of tissue samples using antibodies.
in situ In place, referring to an unresected tumor still in its site of origin in the body, without invasion or metastasis to other locations.
Interstitial cells of Cajal (ICCs) ICCs are cells found in the myenteric plexus and nearby areas between the circular and longitudinal layers of the gastrointestinal tract. Their function is to regulate gastrointestinal motility, or peristalsis, which is the autonomic movement of the GI tract to propel food through the system. The ICCs initiate and propagate the slow wave activity of gastrointestinal wall muscles. Either ICCs, or the more primitive cells that give rise to ICCs, are the source of gastrointestinal stromal tumors.
intramural “Within the wall,” referring to the wall of the gastrointestinal tract. GISTs begin their development in the layer of the GI tract wall between the circular and longitudinal muscle layers, and a very small GIST may still be contained intramurally. Eventually most GISTs grow outward, breaking through the muscle layer.
jejunum The section of the small intestine between the duodenum and ileum.
kinase A kinase is an enzyme (catalyst) that transfers the terminal phosphate group from ATP to a substrate (phosphorylation). KIT and PDGRFA are both tyrosine kinases.
KIT (Also known as CD117, Stem Cell Factor Receptor, and Steel Ligand Receptor). KIT is a transmembrane glycoprotein from the type III receptor tyrosine kinase family. KIT is the receptor for the growth factor Stem Cell Factor, also known as “steel factor” or “KIT ligand.” As a result of interaction with Stem Cell Factor, KIT initiates essential signal transduction pathways that transmit biological signals for cellular proliferation, survival, differentiation, and migration. KIT is expressed on almost all hematopoietic progenitor cells, melanocytes, mast cells, and interstitial cells of Cajal from the digestive tract. Aberrant expression or mutations of the c-kit gene is involved in the pathogenesis of several cancers, including GIST. KIT is structurally similar to the Platelet-Derived Growth Factor receptor (PDGFR).
leiomyoma Non-malignant tumor of smooth muscle cells.
leiomyosarcoma Sarcoma of smooth muscle cells. Prior to the discovery in 1998 that KIT expression could distinguish GISTs as a separate type of sarcoma, most GISTs were diagnosed as leiomyosarcoma.
ligand A ligand is a molecule that binds to (links to and forms a complex with) a specific complementary site on another molecule. For example, growth factors are ligands for corresponding growth factor receptors. With respect to GIST, the KIT ligand binds to and activates the KIT receptor in normal cells, but KIT becomes activated without its ligand in GIST.
loss of heterozygosity Allelic heterozygosity is a state in which genetic material from each of the two parents is present in the cell. Loss of heterozygosity (LOH) is caused by a deletion, mutation, or loss of an entire chromosome (or a region of the chromosome) from the cell nucleus. LOH results in a deletion of one of the parent’s genetic material to part of the genome. LOH is a common occurrence in cancer. It often indicates the presence of tumor suppressor gene in the lost region. Frequently, the remaining copy of the tumor suppressor gene will be inactivated by a mutation. Loss of heterozygosity can arise by two methods. In the first, a region of a chromosome is deleted, resulting in only one copy remaining. In the second, genetic recombination leaves the cell with two copies of the chromosomal region, but both come from the same parent. For an illustration see this PubMed book link.
lumen The hollow food passageway of the gastrointestinal tract.
malignant Cancerous. A tumor having the properties to invade and destroy nearby tissue and spread (metastasize) to other parts of the body.
melena The passage of black, tarry stools indicating the presence of blood in the feces. This may be a symptom of GIST.
mesenchymal General term for soft non-organ tissues. It includes the connective tissues, collagen, neural tissue, smooth and skeletal muscle, cartilage, tendons, ligaments, and fat.
mesentery The membranes (part of the peritoneum) that connect the small intestines to the back abdominal wall and provide blood supply, lymph drainage, and nerves.
metastasis (noun), metastasize (verb). Metastasis is the spread of cancer to another site in the body via cancer cells circulating in the blood or lymph. GIST metastasis is usually blood-borne, as GIST rarely invades lymph nodes.
mitosis Ordinary division of a body cell (a somatic cell) to form two daughter cells, each with the same chromosome complement as the parent cell. It is the process by which the body grows and replaces cells. NOTE: The term mitosis is used interchangeably with cell division, but strictly speaking it refers to nuclear division.
mitotic count The mitotic count is a value that the pathologist obtains by examining a section or specimen of a tumor under the high-powered lens of a microscope. Usually the pathologist will report the number of dividing cells as seen in every fifty fields of view (hpf’s). The lower the number the better in the case of cancer cells.
morphology The form and structure of a particular organism, organ, or part.
mucosal Pertaining to the mucous lining of various tubular structures (including the gastrointestinal tract).
multifocal When used in reference to tumors, multifocal means a group of several tumors that appear to have started individually (not spread from a single original tumor). This is often true of GIST in children, familial GIST, and GIST in NF1 patients.
mutation A permanent transmissible change in genetic material, usually in a single gene. A mutation occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message. This change may occur within a gene or involve larger regions of a chromosome. Mutations within single genes are actual chemical changes to the nucleotide sequences of the constituent DNA. In chromosomal mutations, the number of chromosomes may be altered, or segments of chromosomes may be lost, amplified or rearranged. Mutations can be caused by copying errors in the genetic material during cell division and by exposure to radiation, chemicals, or viruses, or can occur deliberately under cellular control during the processes such as meiosis or hypermutation. In multicellular organisms, mutations can be subdivided into germline mutations, which can be passed on to progeny and somatic mutations, which (when accidental) often lead to the malfunction or death of a cell and can cause cancer. Some germline mutations result in adaptive advantages for species survival, and are considered to be the driving force of evolution.
myenteric plexus (also called Auerbach’s plexus) A network of nerve fibers and neuron cell bodies tucked in among the interstices of the fibers in the tunica muscularis (muscular, usually middle, layer of an anatomical structure). The plexus is an important component of the entire digestive tract. It is found not only in the stomach, but in the esophagus and intestines as well. Importantly for GIST, interstitial cells of Cajal from which GIST may originate, are found in the myenteric plexus (as well as in other locations). The following PubMed link shows an illustration of the location of the myenteric plexus between the circular and longitudinal muscle layers of the wall of the gastrointestinal tract. linkhere
myoblast An undifferentiated or embryonic precursor cell, capable of giving rise to a muscle cell (muscle fiber). From myo- pertaining to muscle, and blast- a formative unit of living matter: a bud, sprout, or germ.
necrosis The sudden, “unprogrammed” death of living cells or tissues. Necrosis can be due, for example, to ischemia (lack of blood flow). It may affect groups of cells or part of a structure or an organ. In contrast to apoptosis (controlled “programmed” cell death) necrosis results in cellular materials being “spilled” into the body. When tumors grow large enough to outgrow their blood supply, the central portion of the tumor often becomes necrotic.
neoplasm Any new and abnormal growth (also called tumor); specifically a new growth of tissue in which the growth is uncontrolled and progressive. The word neoplasm is not synonymous with cancer. A neoplasm may be benign or malignant. Malignant neoplasms are distinguished from benign in that the former show a greater degree of anaplasia (a loss of differentiation of cells and of their orientation to one another) and have the properties of invasion and metastasis.
neurofibroma Flesh-colored benign growths of varying sizes and shapes on the skin of persons affected by a deficient neurofromatosis 1 (NF1) gene. There may be fewer than 10 of these growths or they may number in the thousands.
neurofibromatosis 1 (NF1) NF1 is a condition characterized by multiple cafe au lait spots, freckling, neurofibromas of the skin, and Lisch nodules in the iris of the eyes. Less common but potentially more serious manifestations include a variety of tumors. Heterozygous mutations of the NF1 gene are responsible for the vast majority of cases of neurofibromatosis. The NF1 gene encodes the tumor-suppressor protein neurofibromin. GISTs are unusually common in persons with NF1, occurring in 5-25% of affected people; the GISTs are usually located in the small intestine and are usually multiple, but they may not cause any symptoms. A comprehensive discussion of NF1 is provided at this link:linkhere
nuclear atypia Abnormal appearance of the nucleus of a cell. Cancer cells may display nuclear atypia.
occult bleeding Concealed from observation. Occult blood is hidden from the eye but is nonetheless present and can be detected by chemical tests. For example, bleeding from a tumor into the gastrointestinal tract can be detected by testing a stool sample. If there is enough blood loss, the stool will appear black.
omentum The greater omentum is a part of the peritoneum attached to the greater curvature of the stomach and hanging down over the intestines. The lesser omentum is a part of the peritoneum attached to the liver and to the lesser curvature of the stomach. GIST can occur in the omentum rarely as the primary tumor site. GIST may also metastacize to the omentum.
oncogene An oncogene is a mutated gene that can cause cancer. A normal gene with cancerous potential is called a proto-oncogene. After mutation, the oncogene can continuously simulate unregulated cell proliferation, leading to a tumor. With respect to GIST, mutant KIT or mutant PDGFR are oncogenes.
p16 p16 is a major tumor suppressor gene whose frequent loss occurs early in many human cancers. It is also called INK4 or INK4A because it is the prototype member the INK4 family – inhibitors of cyclin-dependentkinase CDK4. The function of the p16 protein has been implicated in cell cycle control, anoikis (cell death induced by loss of cell adherence or inappropriate cell adherence.), and senesence (an aging process in which cells can no longer divide).
p53 The designation “p53” stands for “protein 53 kilodaltons” in size. p53 gene encodes a protein that regulates the cell cycle for division and growth, and hence functions as a tumor suppressor. It is very important for cells in multicellcular organisms to suppress cancer. P53 has been described as “the guardian of the genome”, referring to its role in conserving stability by preventing genome mutation. The p53 gene is the most commonly mutated gene known in human cancer. Like other tumor-suppressor genes, p53 normally controls cell growth. If p53 is physically lost or is not functioning (because it has been inactivated), this may permit the cell to divide without restraint. Click below for an image of the P53 protein (from Wikipedia). linkhere
paraganglioma A tumor of the chromaffin cells. Paraganglioma is one component of Carney triad.
peristalsis The movement by which the alimentary canal and other tubular organs propel their contents; it consists of a wave of contraction passing along the tube for variable distances. In the stomach, this motion mixes food with gastric juices, turning it into a thin liquid.
peritoneum The membranous sac that supports the abdominal organs and provides thier blood supply.
pleomorphic Many-formed. When a tumor is called pleomorphic, it means that the tumor contains cells of different shapes or morphologies. A pleomorphic GIST could be composed of spindle cells (long thin shape), epithelioid cells (round or polygonal), and perhaps other cell types.
primary tumor A tumor that is at the original site where cancer first arose. For example, a primary brain tumor is one that arose in the brain as opposed to one that arose elsewhere and metastasized (spread) to the brain. The original tumor is sometimes called “the primary.”
prognosis The prediction of what is likely to happen in a disease; a forecast of the outcome of a disease.
proliferation Proliferation is a growth of tissue by reproduction of cells through cell division. Cancer cells are very prolific; they have high rates of cell division, causing tumor growth. Most GISTs display inappropriate, overly active growth factor signals (KIT or PDGF) stimulating tumor cell proliferation.
PTEN Phosphatase and Tensin Homolog (PTEN) is a tumor suppressor gene. The PTEN protein modifies other proteins and lipids (fats) in cells by removing phosphate groups. The PTEN protein is a type of enzyme called phosphatase. When the PTEN enzyme is functioning properly, it acts as part of a chemical pathway that signals cells to stop dividing and causes cells to undergo programmed cell death (apoptosis) when necessary. These functions prevent uncontrolled cell growth that can lead to the formation of tumors. The PTEN gene may play a role in cell migration and adhesion of cells to surrounding tissues. Noninherited (somatic) mutations in the PTEN gene may play a role in the development of several types of cancer.
RECIST This abbreviation stands for Response Criteria in Solid Tumors. It is a system or measuring tumor shrinkage or progression in terms of the longest dimensions of the tumor on imaging scans such as CT. A “partial response” requires a decrease of 30% or more in the longest dimension of a single tumor or in the sum of the longest dimensions of a group of target lesions. “Progression” requires an increase of at least 20% in the monitored longest dimension (or sum). “Stable disease” falls in between these two: a shrinkage of less than 30% or an increase of less than 20%. The RECIST guide is often used to quantify results in clinical trials. In GIST response to tyrosine kinase inhibitor drugs such as imatinib or sunitinib, the RECIST method does not capture improvement in symptoms and quality of life, so it underestimates the benefit of drug therapy. For a free-access medical paper detailing the RECIST criteria, see this link: linkhere
rectum The extreme lower end of the colon (large intestine) leading to the anus.
resect Resect (verb), Resection (noun). To remove tissue an organ or tumor by surgery. Resect and excise are not synonymous. Excise implies total removal whereas resect need not. “R0” resection indicates complete removal of all tumor with microscopically clean margins. “R1” resection indicates that the margins of the resected parts show tumor cells when viewed microscopically. “R2” resection indicates that portions of tumor visible to the naked eye were not removed.
residue A term used to refer to a specific amino acid within a protein’s structure. For example, the KIT protein is 976 amino acids in length. The normal (amino acid) “residue” at position 560 is valine.
retroperitoneum The space between the posterior parietal peritoneum and the posterior abdominal wall, containing the kidneys, adrenal glands, ureters, duodenum, ascending colon, descending colon, pancreas, and the large vessels and nerves. GISTs arising from the duodenum may be retroperitoneal.
RNA The copy made of DNA prior to cell division. It can be thought of as a “working copy” of the master gene template. Prior to formation of the daughter cell, the RNA is reduced by discarding portions called introns and rejoining the remaining portions called exons to form messenger RNA (mRNA).
Roux-en-Y This surgical procedure is a form of gastrectomy that may be performed either for weight-loss purposes OR for cancer involving the stomach. When used to remove cancer, the Roux-en-Y procedure is a total gastrectomy in which the neck of the stomach (cut just below the esophageal sphincter) is joined to the small intestine, bypassing the normal route through the stomach and duodenum. The duodenum is cut off below the pylorus sphincter and the stomach is removed. The duodenum’s connection to the small intestine is moved down, allowing liver bile and pancreatic secretions into the duodenum to reach the small intestine. The following link illustrates the before and after configurations of the GI tract. linkhere
sarcoma A malignant tumor arising in the connective, or supportive, tissue (such as fat, muscle, blood vessels, deep skin tissues, nerves, bone, cartilage). GIST is one type of sarcoma. Sarcomas comprise about 1% of cancers in adults, while the other 99% are carcinomas that affect epithelial tissues (skin and body cavity linings).
Schwannoma A tumor that arises from the Schwann cells, the cells that form the myelin sheath around the peripheral nerve fibers.
serosal of, or relating to, serosa. Serosa is basically a single layer of thin cells resting on connective tissues and secreting a serous (thin, watery) fluid. This type of membrane (cells) line body cavities, or enclose organs contained in these cavities. For example, the mesentery and peritoneum that support the gastrointestinal tract are serosal membranes.
small intestine The longest part of the digestive tract, extending between the stomach and the large intestine. The small intestine is divided into the duodenum, jejunum, and ileum. It is the site where most of the digestion and food absorption occurs.
sporadic Occurring occasionally in a random, or isolated, manner. With respect to GIST, most cases of GIST are sporadic, with no familial component or known environmental carcinogens contributing to the cause.
stoma An artificial opening, especially in the abdominal wall, made in surgical procedures.
stromal Relating to connective tissue serving a supporting function for organs or other structures.
syncope Fainting: loss of consciousness resulting from insufficient blood flow to the brain.
telomerase An enzyme that rebuilds telomeres. Telomerase is overexpressed in many cancer cells, and contributes to their immortality, or ability to divide endlessly.
telomeres Special DNA sequences at the ends of each chromosome that grow shorter each time a cell divides. Telomeres count the number of cell divisions, and when it shortens to a certain length, the cell will stop dividing (senescence) and eventually die.
tumor suppressor gene A protective gene that normally limits the growth of tumors. Tumor suppressor genes encode proteins that prevent the cell from proliferating (dividing) if it has abnormalities in its DNA. When a tumor suppressor gene is mutated (altered), it may fail to keep a cancer from growing. Some of the tumor suppressor genes that may be involved in GIST include p53, p16, and pTEN.
ultrastructural Describes form and structure at the cellular level which usually can only be viewed with an electron microscope. Sometimes pathologists use ultrastructural characteristics of cells in deciding what cell types are included in a biopsy.
vascular Relating to the blood vessels of the body. The blood vessels of the body, as a group, are referred to as the vascular system. The blood vessels are made up of arteries, veins and capillaries — arteries that pass oxygen-rich blood to the tissues of the body; veins which return oxygen-depleted blood from the tissues to the lungs for oxygen; and the capillaries that are the tiniest vessels and are between the arteries and veins. GISTs are often called “highly vascular tumors” meaning that they have a rich blood supply.