Epidemiology of Cancer(Environmental Biology of

Cancer)

Folder Title: Epidemio

Updated: January 29, 2013

EpiTitle

Epidemiology of DiseasesDistribution of patterns of health and disease.Determination of potential causation that leads to the observed

distribution.

Observational vs Experimental Sciences:• Observe episodes of disease appearance (e.g. geographic "hot-spots"

or occupational or familial patterns) • Retrospective analysis of potential causative associations• Prospective trials to determine causative sources

Determine "Relative Risk" or "Odds Ratio"• Small vs large Relative Risk Values

Association or Correlation is not Causation

Complications in Epidemiological Observations Reliable reproducible data and conclusions vs.

firmly held beliefs or "common sense" assumptions.

Problems with acquisition of data and data reliability:• Time patterns of exposure vs appearance of disease• Combinations of causative sources and sequences of exposures• High background appearance (non-rare diseases)• Usually small impact of an agent on an individual or population• Retrospective data: recall bias and data reporting• Prospective trials: Costs, ethical problems, subject cooperation

Deducing Actual Causation from Epidemiological Data

Epidemiological data comparing high and low incidence rates based on different population groups poses the questions:

1.Why is one group presenting high risk for a given type of cancer?

2.Why is another group presenting relatively low risk for that type of cancer?

3.What does that tell us about causation?

4.Does that present possibilities for prevention and diagnosis?

Breast Cancer Relative Risks

Epidemiological data comparing high and low incidence rates based for different types of cancer based on different countries poses the questions:

1.Why is a given cancer (e.g. liver cancer) high in one set of countries?

2.Why is that same cancer very low in other countries?

3.What does that tell us about causation?

4.Does that present possibilities for prevention and diagnosis?

Table 2.5 part 1 of 2 The Biology of Cancer (© Garland Science 2007) p. 44

Table 2.5 part 1 of 2 The Biology of Cancer (© Garland Science 2007) p. 44

Solar exposure & skin pigmentation?

Epstein-Barr Virus Association?

Hepatitis B VirusPapilloma viruses Papilloma viruses

Helicobacter pylori infectionSmoking

??

Please respond to this question as a fill-in-the-blank question using the directions provided in the hand-outs.

Liver cancer is greatly elevated in Hong Kong and in other places in South East Asia. This is due to

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There is elevated risk of breast cancer depending on whether a woman has had a baby or not, and depending on how many

babies she has had. What does this suggest as a plausible response to reduce the risk of death from breast cancer?

1. Get pregnant as often as possible.

2. Monitor and control hormonal status.

3. Deny the evidence and don’t worry about it.

4. Eat a low fat diet.

5. Monitor the high risk group more stringently than the lower risk group.

6. Carry out ovariectomy as early in adult life as possible.

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Epidemiological Data can also sometimes provide clues about the biological mechanisms

underlying certain types of cancers.

Malignant Melanoma (Solar radiation exposure)

Burkitt’s Lymphoma(Co-infection with virus transmitted by

mosquitos also transmitting malaria)

Lifetime Melanoma Risk: 1935 to 1996Figure 7-8, Biological Basis of Cancer, 1998, p 194

MelRisk

White Males

White Females

Black Males & Females

MelRace

Cancer Incidence and Changes in Gene Expression:

Reciprocal Translocation

9 to 22 Reciprocal Translocation:Chronic Myelogenous Leukemia (CML)

8 to 14 Reciprocal Translocation:Burkitts Lymphoma

Figure 1.11b The Biology of Cancer (© Garland Science 2007)

Fluorescent in situ

hybridization (FISH) of

normal metaphase

human chromosomes

using chromosome specific DNA probes with

different fluorescent dyes

Figure 2.23b The Biology of Cancer (© Garland Science 2007)

Chromosome-specific Probe Analysis of Reciprocal Translocation (9 to 22) in Chronic Myelogenous Leukemia

Chromosome 9 (White); Chromosome 22 (Purple)

Reciprocal translocation between chromosomes 9 and 22 produces fusion of a cancer-inducing gene, the abelson or abl

gene with information on another chromosome and gives fusion protein

involving the abl gene product that is mis-expressed and drives cell division in

leucocytes leading to chronic myelogenous leukemia.

Figure 4.13a The Biology of Cancer (© Garland Science 2007) p. 109

Reciprocal Translocation (8 to 14) in Burkitt’s Lymphoma

Figure 4.12 The Biology of Cancer (© Garland Science 2007)

Incidence of Burkitt’s Lymphoma in Relation to Infectious Disease Etiology:Aedes simpsoni mosquito transmission vector for malaria

and Epstein Barr Virus co-infection

Figure 4.13b The Biology of Cancer (© Garland Science 2007 p. 109)

Myc Oncogene (Chromosome 8) Expression Controlled by Fusion with Immunoglobulin Heavy Chain Gene (Chromosme 14) in Burkitt’s Lymphoma

Burkitt’s Lymphoma is Associated with co-infection with a virus carried by mosquitos. This is because the virus:

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1. Causes point mutations

2. Activates antibody synthesis

3. Turns off a cancer suppressor gene

4. Induces a high fever

5. Secretes a potent chemical carcinogen

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What is this slide showing?(Short answer question)

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Epidemiology of Cancer Based on Age

AgeEffct

See Figure 11.1, Cancer incidence at various ages for men and women. p. 400. Weinberg.

Note maximum incidence per 100,000 population at about age 70, then drop off after that age. Serious incidence begins around age 35 except for breast cancer which can have an earlier onset depending on genetics.

Incidence of Various Kinds of Cancers in Men and Women as a Function of Age

Cancer in children and younger adults has an incidence rate of 11% of the total cancers, but accounts for only 5% of the total cancer deaths. Why is that the case? What does that difference between incidence and

mortality tell us about cancers in younger persons? (This is a fill-in-the-blank question. Keep it brief. You

can use abbreviations if they are clear).

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Specific Cancer Incidence and Migratory Patterns:

Cancers and Environmental Effects

See also Figure 7-6, Biological Basis of Cancer, p 191

EatFat

Figure 2.20 The Biology of Cancer (© Garland Science 2007)

Cancer Incidence Following Migration

p. 45

(When this slide opens you do not have to send in your name under “Send User Data” unless you borrowed a Response Card from us this morning.If you borrowed a Card be sure to remove the previous name and enter

your names.

The two previous slides show patterns of cancer incidence within one or two generations in populations

of persons who have migrated .What do these data tell us about causation of these

cancers?You can abbreviate as long as I reasonably can figure

out your meaning.

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Figure 11.2 The Biology of Cancer (© Garland Science 2007)

Cigarette Consumption and Lung Cancer: 1880 to 2000

Carcinogenic Agents and co-Carcinogenic

Agents:Interacting Causations

CigDose

Table 2.6 The Biology of Cancer (© Garland Science 2007)p. 46

CigBooze

Environmental and Occupational

Cancers

CxCauses

WorkCx

Journal of the National CancerInstitute,July, 1996

Kids&Rad

Cultural Associations and Specific Cancers

Journal of the NationalCancer InstituteOctober, 1996

StomCxEthnic

Table 2.7 The Biology of Cancer (© Garland Science 2007) p. 47

Detailed analysis of the epidemiology of cancers is important in cancer medicine because it helps us to

understand __ ___ ___ ___ ___ ___

(or to)

__ __ __ __ __ __ __ some cancers

You only need one response

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Cancer in children 0 to 14 years of age occurs in 15 per 100,000 as the incidence rate. Cancers in that same group accounts for 2.5 deaths per 100,000. What does that tell us

about cancers that affect children ages 0 to 14? (This is a fill-in-the-blank question. Keep it brief. You can

use abbreviations if they are clear).

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Figure 11.3 The Biology of Cancer (© Garland Science 2007)

Male Cancer Death Rates for Various Carcinomas, 1939 to 1947. Log-Log Plot

Slope of 5 indicates a series of rate limiting steps

Figure 11.4 The Biology of Cancer (© Garland Science 2007)

Squamous cell carcinoma in mice.

Mesothelioma in human insulation workers

Cancer Incidence and Carcinogen Exposure

Understanding the epidemiology of cancers allows us not only to understand the causes of some cancers but

also helps us to design programs for the _ _ _ _ _ _ _ _ _ _ of some cancers.

One word only!

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