Cancer Flashcards
cancer
- uncontrolled growth and spread of abnormal cells in the body
- derived from Greek word for crab: karkinos
- group of diseases
- associated with altered genetic expression
- can be fatal
- invasive or metastasizing in nature
- grows rapidly
- angiogenic
- anaplastic - undifferentiated
neoplasm
- “new growth” or “tumor”
- an uncontrolled growth of new cells
- may be benign or malignant
benign
- a neoplasm not capable of metastasizing
- usually not capable of causing death
- can cause illness (due to bulk effect)
malignant
- “cancer”
- neoplasm capable of metastasizing
- capable of causing death
leading cause of cancer death in men and women
lung
incidence of cancer increases with ____
age (77% of cancer diagnosed in people over 55)
lifetime risk of developing cancer in the US
men- 1:2
women- 1:3
5-year survival rate for all cancers
67%
many types of cancer are ____
- 30% of cancer deaths will be caused by ____
- 30% are related to ____
preventable;
tobacco use;
obesity, physical inactivity, and poor nutrition
other preventable causes of cancer
- HPV: vaccine
- HBV: vaccine
- HIV: safe-sex practices, IV drug-use treatment, prophylactic meds
- Helicobacter pylori: antibiotics
- skin cancer: UV protection
cancer can effect ____ parts of the eye
all
~300,000 cases of ocular _____ each year; only 5-10% of ocular tumors are ____
malignancies;
primary to the eye (originate there)
90-95% are metastatic to the eye; frequently spread to the _____
uvea (highly vascularized)
most common cancers that spread to the eye
breast and lung
transformation from normal cells to cancer cell is a ____
years-long process
cancer cells gain ____ through mutation
autonomy
autonomy
independence from normal cellular controls:
- anchorage independent
- immortal
- evade apoptosis
- angiogenic
- self-stimulating
- invasive
telomeres
- protective caps on each chromosome
- become smaller and smaller with each cell division
- loss of telomeres= apoptosis
- telomerase maintains telomeres in stem cells= immortality
- telomerase is reactivated in cancer cells= immortality
non-cancerous cells are anchorage dependent, meaning they only proliferate when ____; cancer cells are ____
attached to a surface; anchorage independent
normal cells exhibit contact inhibition, meaning they ____; cancer cells ___
stop dividing when they form a single layer; do not exhibit contact inhibition, and continue dividing and piling up on top of each other
chronic inflammation creates a ______ environment due to ____
hyperproliferative;
cytokines (cell proliferation, angiogenesis), free radicals (DNA damage leads to DNA mutation)
tumor= wound that ____
fails to heal
cancer causes: 3 main mechanisms
1) chronic inflammation w/o infection (ex: autoimmune disease)
2) chronic infection w/ inflammation (ex: viral, bacterial, parasitic, fungal, etc.)
3) genetic mutations (inherited or environmental)
external causes of cancer
- toxins (workplace, cigarette smoke): DNA damage and/or inflammation
- infections (bacteria, virus, parasite, fungus): DNA damage and/or chronic inflammation
- radiation: DNA damage
internal causes of cancer
- hormonal imbalance (ex: breast, ovarian, colon): hyperproliferation
- autoimmune disease: chronic inflammation
- metabolic disorders: metabolic byproducts can have toxic effects
mutagens
chemical or physical agent that causes a change in the DNA of a cell
carcinogen/carcinogenesis
- any substance that contributes to the development of cancer
- changes DNA or metabolic processes
- causes nonlethal genetic damage**
two types of carcinogens
- initiator (causes genetic damage)
- promoter (promotes tumor growth)
things that are probably carcinogenic
- insecticides
- cisplatin (chemotherapeutic agent)
- nitrates or nitrites
- hairdresser or barber (inhalants)
- very hot beverages
things that are definitely carcinogenic
- plutonium (radioactive)
- benzene (oxidation)
- HPV
- alcoholic beverages
- tobacco smoke
- tanning beds
infection by viruses:
-cause cancer by ____
- inserting genetic material into infected cells
- initiating a chronic inflammatory response
viruses associated with cancers
- hepatitis B and C viruses: hepatic cancer *cause 80% of all liver cancers
- Epstein-Barr virus: Burkitt’s lymphoma
- herpes virus: Kaposi sarcoma
- HPV: cervical cancer*
- lymphoma virus: human T-cell leukemia
infection by bacteria
- helicobacter pylori
- chronic infections = chronic inflammatory response
- more likely with higher concentration of bacteria
- associated with: peptic ulcer disease, stomach carcinoma, mucosa-associated lymphoid tissue (MALT) lymphomas
proto-oncogene
- code for proteins that regulate cell growth and proliferation
- normal and necessary
- capable of becoming an oncogene with one mutation
oncogene
- can cause a cell to become a cancer cell
- come from mutated proto-oncogene
- growth/proliferation no longer regulated
- over-active growth signals (ex: more receptors = more activity)
tumor suppressor genes
- slow down cell proliferation or induce apoptosis when cell damage is present (“anti-oncogenes”)
- mutation allows for unregulated growth by disabling TSG
- both copies must be inactivated for progression of cancer
p53 tumor suppressor gene
- gene products inhibit the cell cycle
- gene activated in presence of damaged DNA
- proteins bind to damaged DNA and stall division
- proteins can initiate apoptosis in the cell at high concentrations
most common type of tumor suppressor gene defect
p53; more than half of all types of human tumors lack functional p53
chemotherapy/radiation triggers ____; ineffective in ____
p53-mediated cell death (cause DNA damage on purpose which should trigger p53 to induce apoptosis);
cancer cells lacking functional p53
point mutations
- changes in one base pair
- can be inherited or acquired
gene amplification
- duplication of a small piece of chromosome over and over
- can result in an increased expression of an oncogene
chromosome translocation (in somatic cells)
- piece of one chromosome is transferred to another
- leads to excess production of an abnormal protein or a novel protein
example of chromosome translocation
- chronic myeloid leukemia and Philadelphia chromosome
- chromosomes 9 and 22= new protein that promotes growth of myeloid progenitor cells
caretaker genes
- maintain genetic integrity (aka. gene repair- review and correct any damage that occurs in DNA)
- loss of these genes leads to increased mutations
chromosome instability
- increased in malignant cells
- occurs during mitosis
chromosome instability can lead to:
- chromsome loss
- loss of heterozygosity
- chromsome amplification
epigenetic mutation
- usually a normal process
- causes: diet, stress, toxins
- effects: inappropriate “gene silencing”
- loss of silencing for oncogenes that leads to cancer
inappropriate gene silencing
- DNA methylation or histone modification
- abnormal silencing of tumor suppressor genes
hereditary cancer characteristics
- germ-line mutations (egg/sperm)
- largely associated with tumor suppressor genes
- rarely associated with oncogenes
- usually heterozygous initially
- at greater risk for cancer resulting from “loss of heterozygosity”, or gene silencing
example of hereditary cancer
Retinoblastoma; approximately half are inherited
Retinoblastoma
- Rb1 gene codes for protein that suppresses cell growth
- Rb1 gene mutated/deleted
- most common primary intraocular malignant neoplasm of childhood
- 5 year survival rate of 93%
- Rb1 gene located on chromosome 13
- can be unilateral or bilateral
- 75% of cases are unilateral
- all bilateral cases are inherited
- usually confined to eye (although it can spread)
clinical signs of retinoblastoma
- leukocoria (white pupil)
- strabismus
- loss of vision
