Epidemiology of Cancer

Question 1

3 top cancers males (incidence)

Answer 1

prostate
lung
colon

Question 2

3 top killer cancers (males)

Answer 2

lung
prostate
colon

Question 3

3 top cancers females (incidence)

Answer 3

breast
lung
colon

Question 4

3 top cancer killers females

Answer 4

lung
breast
colon

Question 5

2 reasons why cancer more common in old

Answer 5

accumulation mutations

decline in immunity

Question 6

unique age demographic

Hodgkins lymphoma?

Answer 6

30

Question 7

unique age demographic

ALL

Answer 7

12ish

Question 8

4 well known chemical carcinogens

Answer 8

polycyclic aromatic hydrocarbons
aromatic amines
nitrosamines / amides
aflatoxins

Question 9

“activation” by microsomal enzymes

Answer 9

large family of microsomal enzymes (p450) that oxidize lipophilic compounds and allow their excretion - oxidation at carbon atoms can form epoxides and at nitrogen and sulfur atoms, can yield products which are mutagenic

Question 10

chemical carcinogenesis - import of microsomal enzymes?

Answer 10

microsomal enzymes metabolize into active forms

the active metabolite is strong electrophile

these electrophyillic species can chemically modify proteins, RNA, and DNA

Question 11

which bases can be attacked by electrophiles?

Answer 11

all 4

Question 12

AMES TEST

Answer 12

measures the abilty of a chemical (in the presence of cytochrom p450 enzymes) to mutagenize salomenella (back to histadine+)

Question 13

what percent of chemicals shown to be carcinogenic in animal testing are mutagens?

Answer 13

90% produce mutations in chromosomal DNA

Question 14

Potency of mutagen parallels its

Answer 14

carcinogenicity

Question 15

are mutagens prevelant

Answer 15

YES! we consume about 1g per day!

Question 16

principles of cancer learned from animals? (7)

Answer 16

the effect of a chemical is generally dose dependent

specific carcinogen –> specific cancer

carcinogenesis requires time

carcinogenesis requires cell proliferation (tissue with rapid division more susceptible)

mutations are stably transmitted to daughter cells

stem cell is the at risk cell - a fully differentiated cell can never become malignant

malignant cell = stem cell that fails to differentiate normally

Question 17

cancer develops in two stages

Answer 17

1. initiation - caused by mutagen - irreversible

2. promotion - caused by chemical which is not mutagenic - is reversible

Question 18

promoter of cancer?

Answer 18

often irritants that cause inflammation and cell proliferation

Question 19

somatic theory of cancer?

Answer 19

cancer cells contain mutations in specific genes that participte in cell growth and differentiation - patients with defect in DNA repair are prone

Question 20

The environment plays a major role in causing cancer - 3 takeaways?

Answer 20

1. significant variation in the incidence of specific cancer seen regionally in countries
2. larger variation in incidence between countries
3. migrants adopt the risk of country they moved to
   * 80% caused by env.

Question 21

what are carcinogens?

Answer 21

highly reactive chemicals that cause mutations in DNA

Question 22

What is a major promoter of cancer?

Answer 22

inflammation 
e.g. 
ulcerative colitis
cholecysitits
osteomyelitis
hepatitis
pancreatitis
schistosomiasis (bladder cancer)