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51 Cards in this Set
- Front
- Back
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whats more important in cancer exercise or food
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exercise
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what is "environment"
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not just the air you breathe but also the culture, lifestyle and diet
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what % of cancer risk is due to environment? what about heredity
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environment: 80-90%
Genetics: 20-10% |
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how can you determine if its genetic or enviornment
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take a group of japanese (same genetics) and put them in a different environment. immigrants
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what are the 3 ways suspected carcinogens are assessed
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1. Ames tes
2. animal testing 3. epidemiological studies |
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what are the two main categories of carcinogens
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1. initiating agents: damage DNA nad introduce mutations. Na nitrate, heteroclycic amines, alcohol metabolized in the liver
2. Tumor Promoters: facilitates proliforation of initiated cells. ex salt, alcohol in the mouth |
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give an example of initiating carcinogens
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1. Na nitrate
2. heteroclyclic amines 3. polycyclic aromatic hydrocarbons, EtOH in liver **initiators will induce DNA damage |
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give examples of tumor promoter carcinogens
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1. salt in the stomach
2. EtOH in the mouth **promoters will aid in proliforation |
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incopmplete carcinogen
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does ONLY initiation OR promotion but not both
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complete carcinogen
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doese BOTH initiation AND promotion in the same tissue
ex tobacco |
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what does the Ames test do?
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uses bacteria to determine the ability of an agent to CAUSE a mutation
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what does animal testing do?
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can determine cause and/or prevention of an agent in mice/rats
**introduce preventative meds in an environment that the aminal will get tumor **expose animal to suspected carcinogen |
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what do epidemiological studies do?
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uses human populations
Retrospective study analyses past behavior/environment and cancer risk **can also use prospective study to analyze future exposure/behavior and cancer incidence |
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how does the Ames test work
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mutated bacteria are cultured with carcinogens and plated on nutrient deficient agar. if bacteria grow they were mutated such that they can now make the previously mutated gene
**agent is a carcinogen |
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what happens to the bacteria if exposed to a non carcinogen in the ames test? what if the agent was a carcinogen
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they die,
they live |
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can the Ames test be used to test precarcinogens?
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yep. plate with liver homogenate
**precarcinogens become carcinogens after metabolism in the liver |
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a drawback to the AMES test
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mutagens in bacteria arent always the same as ppl mutagens
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what type of carcinogen is exposed by the AMES test, which one is not
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initiators are exposed: they cause DNA damage
Tumor promoters: dont initiate damage but will cause proliforation of mutated DNA are NOT exposed by the ames |
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how are animal studies conducted
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animals are given suspected carcinogens at increasing doses and monitored for tumor development. it is thought that if tumor formation increases as level of carcinogen increases then its cancerous
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what type of carconogen exhibits a linear correlation btwn carcinogen dose and cancer development
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initiating factors
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what type of carcinogen displays a threshold relationship btwn levels of carcinogen and cancer development
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tumor promoters
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whats the doseage problem associated with using aminal models
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researches give MASSIVE doses of carcinogen to speed the process and reduce the number of animals needed
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whats the problem with extrapolating carcinogen doses from a linear high dose curve? what is this term?
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at high doses something may cause Cancer but in lower doses it will not so using an extrapolation isnt accurate
**especially in tumor promoters **threshold |
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do high does studies under or overestimate cancer incidence
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OVER
threshold: cancer will only develop if the level of exposure is above a threshold value, below that no cancer will form **common in tumor promoters to have threshold, initiators will often be linear |
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whats the problem with using mice to estimate cancer risk in human
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not always same risk
*ppl get epithelial cancer (carcinoma), mice get CT (sarcoms) and leukemia cancer **ppl often metastisie, mice rarely do |
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what was the delany amendment
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FDA said additives werent safe if it caused cancer in rats. BUT it didnt give limits, so MASSIVE (unrealistic) doses of sacchrin (sweet n low) were given and ppl stoped eating sweat n low even thouhg it was safe
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what happened with saccharine
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delany made them say it was unsafe even though it way. ppl would have had to had 800 cans of soda a day
**what really happened at such high doses was crystal formation which lead to inflammation and the inflammation caused the cancer |
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what are the 5 biases in epidemiological studies
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1. selection
2. experimenter 3. detection 4. publication 5. confounding factors |
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describe selection bias
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participants in the study can skew the test. lets say we select only kids who go to daycare as a representation of an entire city. BAD selection
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what in the intrinsic bias in secondary preventative studies
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1. selection: they are selecting ppl who previously exhibited a particular cancer to determine the type of chemoprevention on recurrence of same cancer
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describe experimenter bias
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scientist can be influence by the outcome
**ie when a drug company hires the research the research will support the drug company **removes researchers objectivity |
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describe detection bias
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detection may be found more bc ppl in that area are screened more or have better access to care
**detection of cancer is altered for reasons other than prevalence |
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describe publication bias
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journals ususally only publish positive/correlative results
*there may have been 15 that said NO correlation but the one that found a correlation was published |
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describe confounding factors
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ex did one population have much higher BMI?
related to the factor being investigated but independently affect risk *complicate studies and must be adjusted for |
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how can you get better results for suspected carcinogens
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use several tests. epidimological AND animal
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what is a meta analysis
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a comosite of all of the paper of a given topic
of 17 papers 16 said X and 1 said Y |
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what were the results of the human cancer meta analysis. 4 stong correlators of cancer
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1. red/processed meat: colorectal cancer
2. salt: stomach cancer 3. Alcohol: oral liver colorectal breast cancer 4. Obesity: esophageal, pancreatic, colorectal, breast, endometrial, kidney cancer |
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how do cooked meats increase the risk of cancer
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heterocyclic amines: initiating factors formed when cooking at high temp
HA form DNA adducts |
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in what way do heterocyclic amines enter the body
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precarcinogens, then they are metabolized in the liver and make initiating factors: adduct on DNA
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what will decrease the amount of heterocyclic amines that are in meats
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microwaving it a bit first
**high heat causes HA formation |
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what are polycyclic aromatic carbons
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initiating carcinogens from grilled food. they are in the smoke and stick to the food
**they form DNA adducts and introduce mutations |
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what are two initiating factors you can get from grilling food
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1. heterocyclic amines: from the high temp
2. polycyclic aromatic hydrocarbons: from fat dripping and smoking and the smoke sticking to food |
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how do nitrates affect DNA
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causes oxidative deamination that created DNA mispairing
**nitrates are perservatives are found in processed meats: bacon, salami, hot dogs |
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how does salt increase cancer
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salt causes proliforation, tumor promoter
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what causes increased risk of stomach cancer
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H pylori: causes chronic inflammation
salt: increases proliforation |
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why is alcohol an initiating factor inthe mouth
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salivary bacteria metabolize alcohol to acetaldehyde which forms adduct, causes point mutations, and breaks repair mechanisms
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does alcohol in the liver contribute to cancer by the same mech as it does in the mouth?
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Nope, in the mouth acetaldehyde is made and causes damage
*in the liver there is effecient metabolism of aldehydes so thats not the problem, the problem is the oxidative damage that results from free radical formation during EtOH metabolism |
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what does the oxidative damage that results from EtOH metabolism in the liver do?
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ROS created by EtOH metabolism leads to DNA breaks, adduct formation, lipid peroxidation
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why does obesity cause cancer
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the fat cells become unregulated and they secrete insulin, estrogen, insulin like growth factor
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in ppl with the same body weight will the one who is active have higher or lower cancer risk?
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LOWER
**exercise is the BEST way to prevent cancer |
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name 8 ways to prevent cancer
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1. healthy weight
2. exercise 3. avoid excess sugar, E dense foods 4. eat fruits/veggies 5. limit red meat, no processed meat 6. avoid alcohol 7. limit salt 8. get nutrition through diet, NOT supplements |
