park-neoplasia Flashcards
neoplasia
-dysregulated cell proliferation
-abnormal growth of cells or tissue
What are the two types of neoplasia?
malignant tumors (cancers)
benign tumors
Malignant tumors
-large
-poorly demarcated
-rapidly growing with hemorrhage and necrosis
-locally invasive
-metastatic
-poorly differentiated
benign tumors
-small
-well demarcated
-slow growing
-noninvasive
-non metastatic
- well differentiated
Naming of benign tumors
-adding the suffix -oma to the parenchymal tissue type
-ademona (glands), osteoma (bones), hemangioma (blood vessels), leiomyoma (smooth muscle), neuroma (neurons), glioma (glial cells)
Naming malignant tumors
-carcinoma
-sarcoma
-leukemia
-blastoma
carcinoma
-malignant tumor of epithelial tissue origin
-adenocarcinoma
sarcoma
-malignant tumor oc connective, muscle, endothelial tissues
-osteosarcoma, leiomyosarcoma, hemangiosarcoma
leukemia
-malignant tumor of blood cells
blastoma
-malignant tumor of precursor cells
-neuroblastoma, glioblastoma, retinoblasta
What are characteristics of cancer cells
-loss of cell differentiation
-genetic instability
-growth factor independence
-loss of cell density-dependent inhibition
-anchorage independence
-faulty cell-to-cell communication
-unlimited life span
-antigen expression
-abnormal production of proteins, hormones, etc
-cytoskeletal changes
loss of cell differentiation (anaplasia)
-resemblance to undifferentiated or embryonic cells
genetic instability
-aneuploidy (loss of gain of chromosomes)
-intrachromosomal instability (insertions, deletions, and amplifications of genes)
-micro satellite instability (short, repetitive sequences of DNA)
-point muations
growth factor independence
proliferation even in the absence of growth factors
loss of cell density-dependent inhibition
-lack of contact inhibition
-rampant growth without regard for adjacent tissue
-necessary fro invasion
anchorage independence
-cancer cells frequently remain viable and multiply without normal attachments to other cells and the extracellular matrix
-critical for metastasis
faulty cell-to-cell communication
formation of intracellular connections and responsiveness to membrane-derived signals are frequently interfered in cancer cells
unlimited life span
cancer cells can divide unlimited number of times
antigen expression
-cancer cells express many cell surface molecules or antigens that are immunologically identified as foreign (tumor antigens)
-ex. fetal proteins that are not expressed by the comparable cells in adult
-tumor antigen may be clinically useful as cancer biomarkers
abnormal production of proteins, hormones, etc
-cancer cells secrete degradative enzymes that enable invasion and metastatic spread
-cancer cells may synthesize hormones that promote their own growth (ex estrogen production by breast cancer)
-cancer cells may produce and secret procoagulant substances that affect clotting mechanisms
cytoskeletal changes
-changes in intermediate filament, actin filaments, and microtubules
-abnormal cell morphology
-facilitate invasion and metastasis
grading
-determined by microscopic examination of tumor cell morphology (histologic analyses)
-samples for these analyses can be obtained by excision or biopsy, fine needle aspirations, or cytologic (pap) smears
-largely qualitative in nature
-based on the differentiation state and the number of mitoses of the tumor
list the different grades
-grade X (grade cannot be assessed/ undetermined grade)
-grade I (well differentiated/ low grade)
-grade II (moderately differentiated/ intermediate grade)
-grade III (poorly/ high grade)
-grade IV (undifferentiated/ high grade)
two major classes of genes
-oncogenes- genes that encode the proteins that promote cancer
-tumor suppressor genes- genes that encode proteins that inhibit cancer
staging
-base don size of the primary lesion (T), extent of spread to lymph nodes (N), and the presence or absence of metastasis (M)
-largely quantitive in nature
-of greater clinical value
Fundamental principles of carcinogenesis
-genetic changes (mutations)
-two major classes of genes are the targets of this damage
-often a multistep process wth multiple genes involved
two hit hypothesis
-assumption that retinoblastoma requires two mutations
-this hypothesis accurately predicts the number of cases of the cancer over time in hereditary and nonhereditary retinoblastoma
describe the TNM system
-tumore, node, metastasis
-T0-T4
-N0-N3
-M0-M1
retinoblastoma
-some cancers are the result of mutation or deletion of a single gene, and these cancers tend to run in families
-retinoblastoma is a childhood retinal cancer; during development, retinal cells don’t stop dividing when they are supposed to, which results in tumors
-carriers of a mutation in a gene (RB1 a tumor suppressor gene) show increased susceptibility to the cancer (hereditary retinoblastoma) compared with non-carriers (nonhereditary retinoblastoma)
-if bilateral there is a 25%-30% chance of being hereditary and a 0% chance of being nonhereditary
-if unilateral there is a 10%-15% chance of being hereditary and a 55%-65% chance of being nonhereditary
tumor suppressors
-two mutations required for retinoblastoma are the mutation both alleles of the same gene (RB1) which is a tumor suppressor
-the carriers already have a recessive genetic mutation in one allele; one more mutation on the other allele (one hit) can cause the cancer
-non-carriers require mutations on both allele (two hits) to develop the cancer
-most tumor suppressors are recessive and need homozygous deletion/mutation on both alleles
-RB1 and TP54 (gene of p53)
-heterozygous mutations in tumor suppressor genes can be inherited, and families show increased susceptibility to cancer
oncogenes
-altered genes that drive cancer
–translocation that makes a protein with a new function (BCR-ABL)
–mutation that makes a more active version of protein (K-Ras)
–gene duplication and over expression of a normal protein involved in cell growth
-these alterations are dominant and often occur at a single allele
-the normal version is called a “proto-oncogene” (denoted by C-gene)
-BCR-ABLe protein results as a chromosomal translocation. It produces a hyperactive kinase that drives proliferation in leukemia
pediatric cancers
-tend to have single genetic events (mutations, translocations) that are important at a specific developmental time
-if carriers of RB1 do not develop the cancer as children, they won’t get it all (but will pass it on)
adult cancers
-rarely have just a single genetic mutation
-tend to be more hetergenous
-patients have different combinations of mutations
risk factors of cancers
-epidemiological studies of cancer incidence discovered several risk factors of cancers
-age, environmental factors, genetics, inflammation, viruses
age
-cancers frequently require multiple mutations and often take 20 years or more to develop
-two common causes
–accumulation of somatic mutations
–decline in immune function