Download Cancer Epidemiology

Cancer Epidemiology
Professor Mostafa Arafa
Learning Objectives
• Students should be able to:
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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
Initiation
Normal
cell
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Progression
Promotion
Initiated
cell
Pre-cancerous
cell
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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:
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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
Lung and bronchus
31%
Prostate
10%
Colon and rectum
Men
295,280
Women
275,000
27%
Lung and bronchus
15%
Breast
10%
10%
Colon and rectum
Pancreas
5%
6%
Ovary
Leukemia
4%
6%
Pancreas
Esophagus
4%
4%
Leukemia
Liver and intrahepatic
bile duct
3%
3%
Non-Hodgkin
lymphoma
Non-Hodgkin
Lymphoma
3%
3%
Uterine corpus
Urinary bladder
3%
2%
Multiple myeloma
Kidney
3%
2%
Brain/ONS
All other sites
24%
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Cancer Epidemiology
Source: American Cancer Society, 2005.
22%
All other sites
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Estimated New Cancer Cases
Prostate
33%
Lung and bronchus
Colon and rectum
Men
710,040
Women
662,870
32%
Breast
13%
12%
Lung and bronchus
10%
11%Colon and rectum
Urinary bladder
7%
6%
Uterine corpus
Melanoma of skin
5%
4%
Non-Hodgkin
lymphoma
4%
Non-Hodgkin
lymphoma
4%
Kidney
3%
Melanoma
of skin
Leukemia
3%
3%
Ovary
Oral Cavity
3%
3%
Thyroid
Pancreas
2%
2%
Urinary bladder
17%
2%
Pancreas
All Other Sites
21%
All Other Sites
*Excludes basal and squamous cell skin cancers and in situ carcinomas except urinary bladder.
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Source: American Cancer Society, 2005.
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Regional and Local data
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Cancer Epidemiology Concepts
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
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Incidence
Prevalence
Specific
Crude
Adjusted/Standardized
SMR/SIR
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Cancer Epidemiology
Sources
• 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
• Reproductive factors
• Dietary factors
• Socioeconomic status
• Obesity
• Environmental pollution
• Exercise
• Ultraviolet light
• Occupation
• Radiation
• Genetic susceptibility
• Prescription Drugs
• Infectious agents
• Electromagnetic fields
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Cancer Epidemiology
IIdentified Associations
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Tobacco & Lung Cancer
Asbestos & Lung Cancer
Leather Industry & Nasal Cancer
Dyes & Bladder Cancer
Ionizing Radiation & Many Cancers
EBV & Burkitt’s Lymphoma
HPV & Cervical Cancer
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Prevention & Control
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)
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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, populationbased)
• Early detection / screening: best during preinvasive (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 >50yrs 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
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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/KFCC
• American cancer society. http://www.cancer.org/
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Thank you for your kind attention
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