Epidemiology of Cancer and Chemical Carcinogenesis Flashcards Preview

Disease and Defense: Unit 2 > Epidemiology of Cancer and Chemical Carcinogenesis > Flashcards

Flashcards in Epidemiology of Cancer and Chemical Carcinogenesis Deck (39)
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1
Q

80% of neoplasms are caused by what?

A

Environmental factors

2
Q

Give one example of regional difference in cancer.

A

Rate of melanoma more prevalent in the southern half of the U.S. and Colorado where exposure to ultraviolet light is higher

3
Q

Give one example of worldwide differences in rates of specific cancer

A

Esophageal cancer is about 300 times higher in Iran than Nigeria

4
Q

True or False: Second and third generation migrants adopt the cancer risk of the country to which they move.

A

True

5
Q

Tobacco is responsible for ____% of all cancers

A

30

6
Q

Cigarette smoke is responsible for ___% of lung carcinoma

A

85

7
Q

What types of cancer does cigarette smoke cause?

A
Oral pharynx
Larynx
Esophagus
Pancreas 
Bladder
8
Q

What are the top three leading causes of cancer deaths in males in the US?

A

Lung 34%
Prostate 12%
Colon/ Rectum 11%

9
Q

What are the top three leading causes of cancer deaths in females in the US?

A

Lung 21%
Breast 18%
Colon/Rectum 13%

10
Q

What is the lifetime risk of cancer in men in Colorado?

Women

A

1 in 2

2 in 5

11
Q

What is the most common cancer in men?

A

Prostate

12
Q

What did Pott do in 1775?

A

Noted an increased incidence of scrotal cancer among chimney sweeps, attributed it to chronic soot exposure

13
Q

What did Kenneway and Heiger do in 1935?

A

Identified polycyclic aromatic hydrocarbons as the active carcinogens in coal tar

14
Q

What did Berenblum do in 1941?

A

Reported croton oil (a plant oil) “promotes” but does not “initiate” skin tumors in rodents

15
Q

Name four environmental carcinogens.

A
  1. Polycyclic aromatic hydrocarbons
  2. Aromatic amines
  3. Nitrosamines
  4. Aflatoxins

*They become carcinogens once metabolized by CYP450

16
Q

Describe polycyclic aromatic hydrocarbons

A

Formed from incomplete combustion of fossil fuels

Ultimate carcinogen is the diol, epoxide

17
Q

Describe aromatic amines

A

Used in inductrial and consumer products

N-hydroxylation and sulfation are required

18
Q

Describe nitrosamines

A

Formed when 2- amines in food react with nitrous acid in the stomach. (Nitrous acid is produced when dietary nitrite, a common food preservative, comes in contact with stomach acid)

Microsomal hydroxylation leads to a carbonium intermediate

19
Q

Describe aflatoxin

A

Common in moldy grains and ground nuts, especially in the tropics and developing nations where most foods are not refrigerated.

In the US found in moldy corn and wheat

Microsomal epoxidation is required

20
Q

What bacteria produces aflatoxin?

A

Aspergillus flavus

21
Q

Active metabolites are strong….

a. Neutrophil
b. Electrophil

A

Electrophil

22
Q

How do electrophils damage cells?

A

They modify proteins, RNA, and DNA

23
Q

True or False:

All carcinogens need activation by microsomal enzymes

A

False. Some chemicals are direct carcinogens

24
Q

Name two direct carcinogens.

A
  1. Alkylating agents

2. Acylating agents

25
Q

Attack by electrophilic species to generate modified bases or bulky adducts causes what two kinds of mutations?

A

Mispairing and Frameshift

26
Q

Name three examples of non-environmental carcinogens

A
  1. Metal vapors
  2. Arsenic exposure
  3. Thorotrast
    Also…..
    Exposure to vinyl chloride
    Asbestos
    Benzene
    and Radon
27
Q

How does the Ames test work?

A

Measures the ability of a given chemical to mutagenize a specific strain of Salmonella typhimurium

28
Q

Why is the Salmonella typhimurium used in the Ames test unique?

A

Because it is genetically altered to have a nonfunctional histamine gene so it can’t synthesize histamine

29
Q

How does an Ames test work?

A

Place 10^8 His- bacteria on a media plate lacking histamine with a crude fraction of liver enzymes. Place a drop of chemical on and see if bacteria begin to grow

30
Q

Name some foods in which mutagens can be found.

A

Every good food and figs

31
Q

True or False:

Chemicals are generally dose-dependent in causing cancer

A

True for the most part

32
Q

True or False:

Specific carcinogens often cause one specific type of cancer

A

True

33
Q

The greatest risk for developing cancer occurs carcinogens effect which cell population.

A

stem cells

34
Q

Do fully differentiated cells become malignant?

A

No

35
Q

What are the two distinct stages of cancer development?

A
  1. Initiation- Irreversible and direct effect of carcinogen

2. Promotion- Reversible; noncarcinogen

36
Q

What are promoters?

A

They promote cell proliferation

They are often irritants that can cause inflammation

They are not mutagens or carcinogens

37
Q

Name an example of promoters in:

Lung Cancer

Colon Cancer

A

Phenols in cigarette smoke

Bile salts promote cancer in benign polyps

38
Q

Name three disorders that are characterized by defects in DNA repair activities and are prone to develop cancer at a young age.

A

Xeroderma pigmentosum

Ataxia-telangiectasis

Fanconi’s anemia

39
Q

Name two epigenetic effects of carcinogens.

A
  1. Carcinogens can covalently modify proteins and RNAs

2. Many chemical carcinogens are toxic to cells