Keywords: Chapter 5, Neoplasia
Adenoma
A benign tumor arising from glandular epithelium.
Aflatoxin
Natural product of the fungus Aspergillus flavus; extremely potent hepatocarcinogen in many species, including humans.
Anaplasia
Lack of differentiated features in a cancer cell, characterized by cellular pleomorphism (variation in size and shape of cells and their nuclei), enlarged and hyperchromatic nuclei, prominant nucleoli, atypical mitoses, and bizarre cells, including giant cells.
Angiogenesis
Formation of new blood vessels often induced by tumors. Many tumors secrete angiogenic growth factors that stimulate growth of new vessels.
Autocrine growth
Growth of cells without external influences. Typically, the cell secretes its own growth factors, which binds to its own receptor expressed on the plasma membrane of the same cell.
BrCa I
Mutations in the BrCa I gene predispose individuals to increased risk of breast and/or ovarian cancer.
Cancer incidence
Occurrence of new cases of cancer in a defined population in a defined period of time.
Cancer risk factors
Factors, e.g., environmental, genetic, metabolic, which favor the development of cancer.
Carcinogenesis
Process that leads to formation of cancer from normal cells or tissues.
Carcinogens
Agents that cause cancer, may be chemical, physical or viral.
Carcinoma
Malignant neoplasm of epithelial origin.
Carcinoma in situ
Pre-invasive form of carcinoma, does not penetrate the basement membrane.
Clonal origin of cancer
A theory based upon the hypothesis that cancer consists of cells which all originate from a single progenitor cell.
contiguous spread
, not metastasis). Cells can disseminate through the blood, lymphatics or by seeding the surfaces of body cavities.
Desmoplasia
Connective tissue proliferation in response to cancer.
Differentiation
Differential expression of genes that accounts for organ or tissue specific function of mature cells.
DNA repair enzymes
Enzymes that repair DNA damage such as single strand breaks. These enzymes are abnormal in xeroderma pigmentosum.
Epithelioma
A benign tumor arising from squamous epithelium.
Epstein Barr virus
DNA virus of herpesvirus family that causes infectious mononucleosis and has been implicated in Burkitt lymphoma and nasopharyngeal carcinoma.
Gene amplification
Generation of increased copy numbers of a gene; typically found in some forms of cancer; may result in overexpression of the gene.
Glioma
Tumor of the brain composed of glia cells.
Grading of tumors
Histologic assessment of malignancy of a neoplasm usually expressed as grades 1 to 3, corresponding to well differentiated, moderately or poorly differentiated tumors.
Growth factors
Polypeptides that promote cell growth by binding to specific cellular receptors.
Hereditary cancer syndromes
Genetically determined forms of cancer that affect certain families usually in an autosomal dominant manner.
HTLV
Human T-cell Leukemic Viruses (HTLV I and II). HTLV-I is an oncogenic virus causing leukemia/lymphoma. It is endemic in parts of Japan, Africa, and the Caribbean.
Human papilloma virus
Class of DNA viruses that cause papillomatous ("nipple-like") lesions, i.e., warts, benign skin cell papillomas and squamous cell carcinomas.
Immunohistochemistry
Immunologic technique for demonstration of antigens in tissues.
Immunosurveillance
Immunological mechanisms that prevent formation of cancer in the body.
Immunotherapy
A form of cancer treatment based on use of monoclonal antibodies, interferons, or interleukins.
Invasion
Growth of tumor cells infiltrating into normal tissues.
Leukemia
Malignant tumor of hematopoietic white blood cell precursors that results in the entry of malignant cells from the bone marrow into the circulating blood.
Lymphoma
Malignant tumor of lymphoid cells. Typically involves lymphoid organs (e.g., lymph nodes, spleen thymus) but may occur in extranodal lymphoid tissues (e.g., MALT of intestines).
Mesenchymal tumors
Tumors which can be benign or malignant that are composed of mesenchymal cells such as fibroblast, fat cells, muscle cells, etc.
Metastasis
Process that leads to tumor spread from one site to another not directly connected with it (if directly connected, it is
Molecular diagnosis
Techniques of molecular biology used in the diagnosis of tumors.
Mutagen
Any agent that alters genetic constitution of a cell.
Neoplasm
Synonym for tumor, it literally means "new growth".
Nitrosamines
Class of carcinogenic amines implicated in human carcinogenesis; can be formed from nitrites (contained in bacon, among other things) and gastric acids.
Oncogene
Literally, a gene that causes cancer. Proto-oncogenes are a class of genes which code for gene products having critical roles in cell growth and signalling. If activated by a point mutation or amplification, a proto-oncogene becomes an oncogene.
Papilloma
Benign tumor arising from an epithelial layer.
Paraneoplastic syndromes
Clinical symptoms caused by distant effects of tumors which may include various endocrine, hematologic, neurologic and other symptoms.
Point mutation
Mutation of a single nucleotide in a gene that changes the function of the gene product. Point mutations can also result in the generation of a stop codon, resulting in a truncated protein product.
Polycyclic aromatic hydrocarbons (PAH)
Derived from combusted organic materials, PAHs are present in cigarette smoke, charcoal-grilled foods, and car exhaust. They are presumed human carcinogens.
Retinoblastoma
Malignant tumor of the eye related to the loss of the RB (retinoblastoma) tumor suppressor gene. May be congenital and familial or sporadic, bilateral or unilateral.
Sarcoma
Malignant neoplasm of connective tissue origin.
Staging of tumors
Clinical assessment of tumor spread, used for prognosis and therapeutic decisions.
Teratocarcinoma
A malignant neoplasm arising from the ovary or testis that contains a component of embryonal carcinoma, in addition to teratoma-like elements.
Teratoma
Tumor composed of tissues that are derived from all three germ layers, i.e., ectoderm; mesoderm; and endoderm. Usually benign when it arises in an ovary (so-called "dermoid", because it often contains skin and sebaceous material).
Translocation
Chromosomal change that results in the transfer of part of one chromosome to another.
Tumor
Synonym for neoplasia, it literally means "swelling" or mass. Neoplasm is the preferred term.
Tumor antigens
Antigens expressed on tumor cells or secreted by tumor cells into the circulation and body fluids.
Tumor initiation
First stage of tumor induction by a carcinogen, typically brought about by exposure to a single dose of an initiating carcinogen, which results in irreversible DNA damage, thereby generating an "initiated cell".
Tumor markers
Substances that are expressed on tumor cells or secreted by tumor cells. They can be detected by means of immunochemical techniques and are useful in tumor diagnosis.
Tumor progression
Third stage of tumorigenesis in which growth is autonomous.
Tumor promotion
Second stage of tumor induction characterized by repetitive exposure of an initiated cell to a tumor promoter. Promotion is (at least initially) reversible, and dependant on the continued presence of the promoting stimulus.
Tumor suppressor gene
A normal gene whose function is to suppress cell growth or proliferation. Mutation, inactivation or deletion of part or all of one allele of a tumor suppressor gene predisposes that individual to increased risk of tumor development.
Xeroderma pigmentosum
Genetic defect of DNA repair enzymes.