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Lung cancer: a preventable disease

Epidemiology addresses issues related to

Heredity,Life-style, andEnvironment.

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Lung cancer: how did it start?

First described in 1420 in Schneeberg-Austria after the opening of cobalt- and nickel mines.

Incidence was very low in the 19th century. Is now worldwide the commonest form of

cancer in men, and the fifth most frequent cancer in women.

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Cause and effect: cigarette smoking lung cancer

Men started smoking cigarettes in 1920s 20 years later, incidence of lung cancer in men climbed sharply.

In 1940s, women became cigarette smokers 20 years later, a similar dramatic increase in lung cancer among women.

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Yearly incidence rates of lung cancer

0

20

40

60

80

100

120

140

Males Females

Sex distribution

Yea

rly

Inci

denc

e pe

r 10

0.00

0

Maoris in New Zealand

American blacks in San Francisco Bay Area

Inhabitants of West Scotland

Belgium

India

African populations

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Risk factors

1. Tobacco (and passive) smoking 2. Air pollution in urban areas 3. Chronic conditions: COPD 4. Occupational exposure (man-made

mineral fibre)

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Genetic factors

Aryl-hydrocarbon-hydroxlase system (AHH) converts weak carcinogens in cigarette smoke into active carcinogens

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Prevention of lung cancer

80% of lung cancer cases are associated with many years of tobacco smoking, and can therefore be AVOIDED.

10% of lung cancer cases are associated with exposure to occupational carcinogens, and can therefore be AVOIDED.

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Histological types of lung cancer

2 major types: small-cell lung cancer, and nonsmall-cell lung cancer, which is further

subdivided into: squamous cell carcinoma, adenocarcinoma, and large-cell carcinoma.

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Origin and characteristics of various types of lung cancer

Squamous cell lung cancer: commonest type in males, central origin, manifests early

Adenocarcinoma: commonest type in females, peripheral origin, manifests late

Large cell lung cancer: least common type, peripheral origin

Small cell lung cancer: most aggressive type, central origin, spreads quickly

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Snap: Lung Cancer:

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Histological distribution of lung cancer depends on age and sex

In males 35 – 75 years:

Squamous cell carcinoma

Small cell cancerAdenocarcinomaLarge cell cancer

In females 35 – 75 years:

AdenocarcinomaSmall cell cancerSquamous cell

carcinomaLarge cell cancer

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Biology of lung cancer

Oncogenic event pluripotent cell

small cell lung cancer large cell lung cancer squamous cell lung cancer adenocarcinoma

Souhami

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Histological diversity of lung cancer (SCLC)

Pluripotent cell or stem cell can differentiate into:

Small cell lung cancer classical cell line (70%) variant cell line (30%)

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Histological diversity of lung cancer (NSCLC)

Pluripotent cell or stem cell can differentiate into:

Non-small cell lung cancer Squamous cell lung cancer Non-squamous cell lung cancer

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Early detection of lung cancer

High mortality rate is related to low cure rate (13%)

Low cure rate is related to lack of early detection measures

Past screening measures: annual chest x-rays, quarterly sputum cytology have not been successful

Biologic and genetic features offer new possibilities

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Prevention of lung cancer

Primary prevention85 – 87% of lung cancers are caused by tobacco smoking Secondary preventionDiet and vitamin consumtion may play a role. Prevention strategies based on genetic and

biologic changes Replacement of missing suppressor genes?

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Conclusions

No currently established means for the screening or early detection of lung cancer

85-88% of all lung cancers are caused by active or passive exposure to tobacco smoke

Reduction of tobacco consumption still is the most important strategy

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Recommended literature

Doll, Peto et al. “Mortality in relation to smoking: 20 years observation on male British doctors”. Br. Med. J., 1976 (2) pp 1525-1536.

Law MR. “Genetic predisposition to lung cancer”. Br J Cancer 1990 (61); 195-206.

Carney DN. “The biology of lung cancer”. Current topics in lung cancer 1991, pp 3-14.

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More Information on the WWW

CancerNet: Statistical Data Sources UICC GLOBALink Institute of Epidemiology Department of Epidemiology – Links SEER Cancer Statistics Review, 1973-1996 Cancer Epidemiology, Biomarkers Prevention

Table of Contents Lecture Link Application Today’s??-Smoking and Kreyberg Lung Tumors What if I smoke cigarettes?