Introduction to Cancer Epidemiology

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Introduction to Cancer Epidemiology

• Faina Linkov, PhD
• Research Assistant Professor of Medicine and
  Epidemiology
• University of Pittsburgh Cancer Institute
• E-mail (preferred mode of communications) fyL1
  (at) pitt.edu

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University of Pittsburgh Graduate School of
Public Health, one of the oldest school to
advocate for chronic disease epidemiology research
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What this course is about

• Learning more about cancer epidemiology
• Investigating risk factors implicated in cancer
  development
• Learning to write grants and critique articles
• Learning to be passionate about chronic disease
  epidemiology

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True or False?

• Smoking causes lung cancer

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True or False?

• Large percentage of cancers are preventable

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True or False?

• In the past 20 years tremendous improvements in
  the treatment of all cancers have been achieved

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True or False?

• Preventing cancer is easier than treating cancer

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True or False?

• Screening tests are available for most cancers

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Epidemiology

• Distribution and determinants of disease
  frequency in human populations

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Cancer EpidemiologyHistorical Perspective

• 1775
• British surgeon, Percival Pott reported probably
  the first description of occupational
  carcinogenesis in the form of scrotum cancer
  among chimney sweeps.

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Cancer EpidemiologyHistorical Perspective

• Tight corsets and cancer
• 1842
• Rigoni-Stern, Italian physician, observed that
  married women in the city were getting cervical
  cancer, but nuns in nearby convents werent. He
  also observed that nuns had higher rates of
  breast cancer, and suggested that the nuns
  corsets were too tight.

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Five Criteria for a Cause ? Effect Relationship
Criteria Risk Factor for Disease
1) Timing Exposure occurs before development of disease or during its progression
2) Strength Is dose-dependent Cessation of exposure can modify disease
3) Prevalence Occurs in multiple populations
4) Relationship to other risk factors Is independent Can also act synergistically
5) Plausibility Produces structural or functional changes which are events in mechanism of disease
anatomic or molecular
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Cancer EpidemiologyHistorical Perspective

• 1700s tobacco and cancer
• Reports of cancer risks associated with tobacco
  in the 18th century included snuff taking and
  nasal cancer, reported by Hill in 1761, and pipe
  smoking and lip cancer by von Soemmering in 1795.

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Cancer EpidemiologyHistorical Perspective

• Tobacco and Lung Cancer
• Asbestos and Lung Cancer
• Leather Industry and Nasal Cancer
• Dyes and Bladder Cancer
• Ionizing Radiation and Many Cancers
• DES and Vaginal Adenocarcinoma
• EBV and Burkitts Lymphoma
• HPV and Cervical Cancer

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Cancer EpidemiologyAn Introduction

• The Epidemiologic Perspective
• Aims of Cancer Epidemiology
• Methods of Epidemiology
• Historical Perspective and Examples
• Contemporary Studies
• The Future

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Aims of Cancer Epidemiology

• Uncover new etiologic leads
• study of the distribution of cancer
• quantify the risk associated with different
  exposures and host factors
• Promote insights into the mechanisms of
  carcinogenesis
• Assess efficacy of preventive measures
• Investigate predictors of survival

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Types of Epidemiologic Studies

• Cohort
• Case-Control
• Cross-Sectional (Prevalence)
• Other

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Methods of Cancer Epidemiology

• Descriptive Studies
• Incidence, mortality, survival
• Time Trends
• Geographic Patterns
• Patterns by Age, Gender, SES, Ethnicity
• Analytic Studies
• Case-control
• Cohort

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Challenges to Interpretation

• Observational vs. Experimental Design
• Cancer clusters
• Study Design and Conduct
• Study Size
• Biases Misclassification, confounding,
  selection
• Exposure assessment important
• Epidemiology and strong and weak effects
• Impact on a population level
• Replication critical

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Cancer EpidemiologySources

• US SEER Registry System
• IARC International Registries
• State/Hospital Registries
• Etiologic Clues
• Alert Clinician
• Experimental Studies

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Cancer EpidemiologyCurrent/Future Topics

• Infectious Agents
• Cancer and inflammation
• Obesity
• Physical Activity
• Diet
• Hormones
• Immunologic Factors
• Cancer disparities
• Inherited Susceptibility (Polymorphisms)

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Cancer EpidemiologyCurrent/Future Topics

• Tumor (somatic) Alterations
• Cancer Classification
• Biomarkers of Exposure/Effect
• Vaccines
• Survivorship
• Cancer and disability
• Alternative therapy