Cancer Epidemiology

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Cancer Epidemiology

• Professor Mostafa Arafa

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Learning Objectives

• Students should be able to
• Appreciate the historical perspective of cancer
  control
• Explain the Global impact of cancer
• Identify the most prevalent cancers world wide
• Identify the leading causes of cancer deaths
• Understand the cancer control continuum and
  explain its implication to public health
• Explain important factors and trends affecting
  cancer control and directions for future research

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What is cancer?

• Definition
• Cancer is a generic term for a group of more
  than 100 diseases that can affect any part of the
  body.
• Other terms used are malignant tumors and
  neoplasm
• 
  ..WHO

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Biologic Basis for Cancer Control
Normal cell
Initiated cell
Pre-cancerous cell
CANCER
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• What Is Cancer?
• Cancer is a group of diseases characterized by
  uncontrolled growth and spread of abnormal cells.
  If the spread is not controlled, it can result in
  death. Cancer is caused by both external factors
  (tobacco, infectious organisms, chemicals, and
  radiation) and internal factors (inherited
  mutations, hormones, immune conditions, and
  mutations that occur from metabolism). These
  causal factors may act together or in sequence to
  initiate or promote the development of cancer.
  Ten or more years often pass between exposure to
  external factors and detectable cancer. Cancer is
  treated with surgery, radiation, chemotherapy,
  hormone therapy, biological therapy, and targeted
  therapy

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Cancer history
Human cancer is probably as old as the human
race. It is obvious that cancer did not suddenly
start appearing after modernization or industrial
revolution.
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Ancient Egypt (3000 BC-1500 BC) 1

• The oldest known description of human cancer is
  found in 7 Egyptian papyri written between
  3000-1500 BC.
• Two of them, known as the "Edwin Smith" and
  "George Ebers" papyri, contain details of
  conditions that are consistent with modern
  descriptions of cancer.

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Hippocrates (460-370 B.C) 1

• He is the first person to clearly recognize
  difference between benign and malignant tumors
• His writings include description of cancers
  involving various body sites

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Hippocrates (460-370 B.C) 2

• Hippocrates noticed that blood vessels around a
  malignant tumor looked like the claws of crab.
• He named the disease karkinos (the Greek name for
  crab) to describe tumors. In English this term
  translates to carcinos or carcinoma.

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Global Burden of Disease

• Total of 58 million deaths worldwide in 2005,
  cancer accounts for 7.6 million (or 13) of all
  deaths
• Main types
• lung (1.3 million deaths/year)
• Stomach (almost 1 million deaths/year)
• Liver (662,000 deaths/year)
• Colon (655,000 deaths/year) and
• Breast (502,000 deaths/year).

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Cancer incidence for the regions of the world
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• The global burden of cancer continues to increase
  largely because of the aging and growth of the
  world population alongside an increasing adoption
  of cancer-causing behaviors, particularly
  smoking, in economically developing countries.
  Based on the GLOBOCAN 2008 estimates, about 12.7
  million cancer cases and 7.6 million cancer
  deaths are estimated to have occurred in 2008 of
  these, 56 of the cases and 64 of the deaths
  occurred in the economically developing world.
  Breast cancer is the most frequently diagnosed
  cancer and the leading cause of cancer death
  among females, accounting for 23 of the total
  cancer cases and 14 of the cancer deaths. Lung
  cancer is the leading cancer site in males,
  comprising 17 of the total new cancer cases and
  23 of the total cancer deaths.

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• Although overall cancer incidence rates in the
  developing world are half those seen in the
  developed world in both sexes, the overall cancer
  mortality rates are generally similar. Cancer
  survival tends to be poorer in developing
  countries, most likely because of a combination
  of a late stage at diagnosis and limited access
  to timely and standard treatment. A substantial
  proportion of the worldwide burden of cancer
  could be prevented through the application of
  existing cancer control knowledge and by
  implementing programs for tobacco control,
  vaccination (for liver and cervical cancers), and
  early detection and treatment, as well as public
  health campaigns promoting physical activity and
  a healthier dietary intake.

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Estimated Cancer Deaths
Men295,280
Women275,000
27 Lung and bronchus 15 Breast 10 Colon and
rectum 6 Ovary 6 Pancreas 4 Leukemia
3 Non-Hodgkin lymphoma 3 Uterine
corpus 2 Multiple myeloma 2 Brain/ONS 22
All other sites
Lung and bronchus 31 Prostate 10 Colon and
rectum 10 Pancreas 5 Leukemia 4 Esophagus 4 Li
ver and intrahepatic 3bile duct Non-Hodgkin
3 Lymphoma Urinary
bladder 3 Kidney 3 All other sites
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ONSOther nervous system. Source American Cancer
Society, 2005.
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Estimated New Cancer Cases
Men710,040
Women662,870
32 Breast 12 Lung and bronchus 11 Colon and
rectum 6 Uterine corpus 4 Non-Hodgkin
lymphoma 4 Melanoma of skin 3
Ovary 3 Thyroid 2 Urinary
bladder 2 Pancreas 21 All Other Sites
Prostate 33 Lung and bronchus 13 Colon and
rectum 10 Urinary bladder 7 Melanoma of
skin 5 Non-Hodgkin 4
lymphoma Kidney 3 Leukemia 3 Oral
Cavity 3 Pancreas 2 All Other Sites 17
Excludes basal and squamous cell skin cancers
and in situ carcinomas except urinary
bladder. Source American Cancer Society, 2005.
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Regional and Local data
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Cancer Epidemiology Concepts
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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
• Cross-sectional
• 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
• Strong and weak effects
• Impact on a population level

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Rates

• Incidence
• Prevalence
• Specific
• Crude
• Adjusted/Standardized
• SMR/SIR

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Cancer EpidemiologySources

• US SEER Registry System (SEER) Surveillance,
  Epidemiology, and End Results http//seer.cancer.
  gov/
• IARC International Registries
• State/Hospital Registries
• Etiologic Clues
• Alert Clinician
• Experimental Studies

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Known Risk Factors for Cancer

• Smoking
• Dietary factors
• Obesity
• Exercise
• Occupation
• Genetic susceptibility
• Infectious agents

• Reproductive factors
• Socioeconomic status
• Environmental pollution
• Ultraviolet light
• Radiation
• Prescription Drugs
• Electromagnetic fields

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Cancer EpidemiologyIIdentified Associations

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

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Prevention Control
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Comprehensive Approach

• Integrated coordinated approach is needed to
  reduce cancer incidence, morbidity, disability
  and mortality through promotion, prevention,
  early detection, management, rehabilitation,
  palliative care
• This involved combined work of public, private as
  well as civil society agencies

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Primary Prevention (Risk Factor Control)

• Cancer education legislation
• Tobacco / alcohol prevention and cessation
• Diet high fiber, low fat, fruits vegetables
• Weight control
• STI prevention and control
• Monitoring exposure to sunlight / radiation
• RF control (within/outside workplace)
• Lowest estrogen dose, upon prescription

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Secondary Prevention

• Cancer registration (hospital-based,
  population-based)
• Early detection / screening best during
  pre-invasive (in-situ) or pre-malignant stages.
  Examples cervical, breast, prostate, colon,
  oral, skin, testis, etc
• Management multi-modal surgical, chemotherapy,
  radiotherapy, pain therapy

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Lung Cancer

• Risk factors
• Cigarette smoking, environmental exposures,
  tuberculosis
• Detection/Prevention
• Reduce exposure to tobacco smoke

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Breast Cancer

• Risk Factors
• Age, family history, biopsy, breast density,
  early menstruation, obesity after menopause,
  recent use of oral contraceptives, hormone
  therapy, late or no children, alcohol, breast
  feeding, exercise
• Early Detection
• Mammography and clinical breast exam every year
  after age 40 (ACS)

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Prostate Cancer

• Risk factors
• Age, ethnicity, family history, dietary fat?,
  weight?
• Early detection/prevention gt50yrs old
• PSA blood test/yr
• Digital rectal exam/yr

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Colorectal Cancer

• Risk factors
• Age, family history, smoking , alcohol, obesity,
  exercise, high fat diet/red meat
• Early Detection/Prevention
• 4 modalities recommended for people age 50 and
  older
• Fecal occult blood test (FOBT) every year
• Flexible sigmoidoscopy every 5 years
• Colonoscopy every 10 years
• Double-contrast barium enema every 5 years

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References -1

• Adami HO, Hunter D, Trichopoulos D. Textbook of
  cancer epidemiology. 2nd edition. Oxford Oxford
  University Press, 2008.
• Dennis LK, Lynch CF, Smith EM. Cancer. In
  Wallace/Maxcy-Rosenau-Last Public Health
  Preventive Medicine. 15th edition. New York
  McGraw, 2009.
• Brownson RC, Joshu C. Cancer. In Chronic disease
  epidemiology and control. 3rd edition. Washington
  DC American public health association, 2010.

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References -2

• Boffetta P, La Vecchia C. Neoplasms. In Detels
  R, Beaglehole R, Lansang MA, Gulligord M. Oxford
  textbook of public health. 5th edition. Oxford
  Oxford University Press.
• International agency for research on cancer.
  http//www.iarc.fr/
• Centers for disease control and prevention.
  www.cdc.gov
• GCC and KSA national cancer registry.
  http//bportal.kfshrc.edu.sa/wps/portal/bportal/KF
  CC
• American cancer society. http//www.cancer.org/

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• Thank you for your kind attention