Biology of Cancer (Quiz 2) Flashcards
Neoplasia definition
New Abnormal Growth; could be either benign or malignant (also known as a tumor)
Tumor definition
New abnormal growth; could be either benign or malignant (same as neoplasia)
Malignant definition
Cancer “crab”, can invade and destroy adjacent structures and spread to distant sites
- fatal without treatment
- destructive where they’re at
Benign definition
- “relatively innocent”
- remain localized, does not spread distantly (not a whole lot of destruction)
Neoplasia
- new abnormal growth
- loss of responsiveness to normal growth controls (autonomy)
- behave as parasites:
- compete with normal cells for their metabolic needs
- increase in size tumor not individual cells regardless of their local environment and the nutritional status of their host
- spolied king w/peasants example
Nomenclature of benign tumors
- benign tumors are designated with suffix -oma added to the cell type (example fibroma, adenoma)
- names based on cells of origin: adenoma (glandular), cystadenoma (mass on a hollow organ)
- two important exceptions are lymphoma and melanoma which are both malignant
Nomenclature of malignant tumors
main categories:
- sarcoma
- carcinoma
- lymphomas and leukemias
- multiple myeloma
-sarcoma
connective tissue origin
-e.g: fibrosarcoma, osteosarcoma
-carcinoma
epithelial origin
-e.g. adenocarcinoma
lymphomas & leukemias
lymphomas = solid mass of tissue leukemias = proliferate in bloodstream and bone marrow
multiple myeloma
malignant cancer
risk factors for cancer
- genetics and cancer-prone families
- viral causes (HPV)
- bacterial causes (helicobacter pylori)
- tobacco use
- diet
- alcohol consumption
- sexual and reproductive behavior (increase risk for cervical cancer)
- air pollution (free radicals)
- occupational hazards
- ultraviolet radiation (skin cancer)
- ionizing radiation
- sex hormones
- others
how is diet a risk factor for cancer?
- xenobiotics (substitute acts like a drug, hormone or toxin)
- nitrates (lunchmeats)
- low fiber (colon cancer risk)
- obesity
- omega 6 fatty acid: increases risk
- omega 3 fatty acids: decreases risk
- many others
Carcinogenesis
- origin or production or development of cancer
- normal cell division, proliferation, and differentiation is strictly regulated by genetic control
- regulatory genes “turn on” resting cells so that they will divide, and “turn off” proliferating cells
- damage of these genes leads to carcinogenesis
damage of what kind of genes leads to carcinogenesis?
mutations of:
- genes that encode growth factors
- genes that encode growth factor receptors
- genes that regulate apoptosis
- genes that regulate repair of damaged DNA
Oncogenes
regulatory genes, that if damaged may lead to neoplasia
- proto-oncogenes
- tumor suppressor genes
- “proof-reading” genes
Proto-oncogenes
genes that in their normal, non-mutant state, lead to proliferation of cells (code for various pro-growth signals)
Tumor suppressor genes
Genes that in their normal, non-mutant state, stop excessive cell proliferation (code for various antigrowth signals)
“proof-reading” genes
genes that code for DNA error repair enzymes
Telomere
normal cap on DNA at the end of a chromosome
Telomerase
an enzyme that can build the telomere back up (turned off in every adult cell except sperm cells)
Cancer transformation requires multiple mutations
- self-sufficiency in growth signals
- insensitivity to antigrowth signals
- evading apoptosis (via telomerase)
- limitless replicative potential
- sustained angiogenesis (new blood vessels form to supply it)
- tissue invasion and metastasis
transformation
the process by which a normal cell becomes a tumor cell
Tumor progression
- transformation occurs
- benign tumors may further mutate into malignant tumors
- many tumors become more aggressive and acquire greater malignant potential over time
- subpopulations of cells can develop
- most benign tumors stay benign
- frequently reproduces
Differentiation
- process by which cells become different from each other
- normal cells become irreversibly more specialized
- as they become more differentiated, they may lose their ability to replicate
- genes that are normally “turned off” during differentiation can be mutated or reactivated by carcinogenic agents
oncology
backwards embryology
three germ layers
epiderm (skin, neuro)
mesoderm (musculoskeletal)
endoderm (digestive, urinary)
totipotent cell
- undifferentiated
- has the potential to become anything
multipotent cell
germ lines
pluripotent stem cell
more stem-ish than others
Unipotent cell
white blood cells (cells that can only differentiate into one type of cell)
Differentiation of tumor cells
-extent to which the tumor cells resemble their normal forebears, both morphologically and functionally
differentiation of benign tumors
- well differentiated and closely resembles their normal counterparts
- may produce functional hormones, etc.
Differentiation of malignant tumors
- range from well-differentiated to totally undifferentiared (anaplastic)
- a spectrum
Dysplasia
- dysplasia is a disorderly but non-neoplastic proliferation of (usually epithelial) cells
- loss of uniformity (pleomorphic)
- loss of architectural orientation
- mitotic figures more abundant & in abnormal locations
- mild to moderate dysplastic changes may be reversible
- dysplastic changes are often found adjacent to cancerous foci “pre-cancerous”
Carcinoma in SItu
- contained in one spot
- pre-invasive epithelial tumors (NOT pre-cancerous)
- have not yet broken through the basement membrane
- may be erroneously confused with benign tumors
- may be non-invasive for variable periods of time before progressing to invasive carcinomas
- e.g. cervix, breast (DCIS)