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Lung cancer- a preventable disease

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					     Lung cancer: a preventable
     disease

                       Epidemiology
                         addresses issues
                         related to 
                        Heredity,
                        Life-style, and
                        Environment.

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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

                              140

       Yearly Incidence per
                              120
              100.000         100
                              80
                              60
                              40
                              20
                               0
                                    Males          Females
                                                         Sex distribution

                                              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          10% of lung cancer
    cases are associated           cases are associated
    with many years of             with exposure to
    tobacco smoking,               occupational
    and can therefore              carcinogens, and
    be AVOIDED.                    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          In females 35 – 75
 years:                     years:
Squamous cell             Adenocarcinoma
 carcinoma                 Small cell cancer
Small cell cancer         Squamous cell
Adenocarcinoma             carcinoma
Large cell cancer         Large 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 prevention
85 – 87% of lung cancers are caused by
tobacco smoking
 Secondary prevention
Diet 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?
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