Cancer

1. Epidemiology of cancer
Dr Kawkab Al-Haddad

2. Objectives
1. Define cancer
2. Recognize the global burden of cancer
3. Identify causes and risk factors of cancer
4. Understand the different methods of cancer Prevention
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3. Definition of Cancer
A group of diseases characterized by :
1. abnormal growth of cells
2. ability to invade adjacent tissues and even distant
organs
3. the eventual death of the affected patient if the
tumour has progressed beyond that stage when it
can be successfully removed.
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4. Major Categories of Cancer
 Carcinomas , arise from epithelial cells lining the internal
surfaces of the various organs ( mouth, esophagus, intestines,
uterus) and from the skin epithelium.
Sarcomas, arise from mesodermal cells of CT ( fibrous tissue, fat
and bone)
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5. Major Categories of Cancer
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Lymphomas, myeloma and leukaemias arising from the cells of
bone marrow & immune systems
Cancer can occur at any site or tissue of the body and may involve
any type of cells.
primary tumour" is used to denote cancer in the organ of origin
secondary tumour" denotes cancer that has spread to regional
lymph nodes and distant

6. Global burden of cancer
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Global burden of cancer rose to an estimated 18.078 million new cases
with 9.55 million deaths. (2018)

7. Global burden of cancer
1. cancer lung 2.09 million
(11.6%)
2. cancer breast 2.08 million
(11.6%)
3. colorectal cancer 1.849
million (10.2%)
4. cancer prostate 1.276 million
(7.1 %)
5. stomach cancer 1.033 million
(5. 7%).
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8. Cause of cancer deaths
1. Lung 1.76 million (18.4%)
2. Colorectal cancer 0.88 million (9.2%)
3. Cancer stomach 0. 782 million (8.2%),
4. Cancer liver 0. 781 (8.2%)
5. Cancer breast 0.626 million (6.6%)
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9. Sex Spesfic Morbidity and Mortality
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 Lung cancer is the most commonly diagnosed cancer and the leading
cause of cancer death in males, followed by prostate and colorectal
cancer for incidence, and liver and stomach cancer for mortality.
Among females, breast cancer is the most commonly diagnosed
cancer and the leading cause of cancer death, followed by colorectal
and lung cancer for incidence and vice versa for mortality; cervical
cancer ranks fourth for both incidence and mortality.

10. Global burden of cancer
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> 60 % of the worlds total cases occur in Africa, Asia, and Central
and South America, and these regions account for about 70 % of
the world's cancer deaths. Situation is made worse by the lack of
early detection and access to treatment
Decline in cancer incidence rate of cervix uteri and stomach, and
increasing incidence rates of breast, prostate and colorectal
cancers. Reduction in infection-related cancers and increase in cancers associated with reproductive, dietary and hormonal
RF

11. Cancer prognosis
lung cancer accounts for most deaths from cancer in the world
annually, since it is most invariably associated with poor
prognosis.
Appropriate intervention is often effective in avoiding fatal
outcome following diagnosis of breast cancer.
 Hence breast cancer, which rank second in terms of incidence,
is not among the top three causes of death from cancer, which
are respectively cancers of the lung, stomach, and
liver.
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12. Time Trends
Few decades ago, cancer was the sixth leading cause of death
in industrialized countries; today, it is the second leading cause
of death. There are a number of reasons for this increase,
1. longer life expectancy
2. more accurate diagnosis
3. rise in cigarette smoking, especially among males.
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13. Cancer patterns
There are wide variations in the distribution of cancer
Stomach Ca is very common in Japan, and has a low incidence in
United States.
In the South-East Asia , the great majority are oral &cervical Ca.
These international variations of cancer are attributed to
multiple factors e.g EV factors, food habits, lifestyle, genetic
factors or even inadequacy in detection and reporting of cases.
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14. Yemen
Facilities for screening and proper management of cancer
patients are grossly limited in yemen . Most cancer patients are
already in an advanced and incurable stage at the time of
diagnosis. Appropriate strategies should be developed , including
creating public awareness about cancer, tobacco control and
application of self or assisted screening technique for oral,
cervical, and breast cancers. (national cancer program ??)
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15. Causes of cancer
As with other chronic diseases, cancer has multifactorial
etiology.
Environmental factors:
tobacco ,alchol , dietary factors, occupational exposures,viruses,
customs, habits& lifestyles, others
Genetic factors
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16. Environmental factors
• Responsible for 80 to 90 % of all human cancers.
• Tobacco in various forms of its usage (e .g. , smoking, chewing)
is the major environmental cause of cancers of the lung, larynx,
mouth, pharynx, oesophagus, bladder, pancreas and probably
kidney.
•It has been estimated that cigarette smoking is responsible >
one million premature deaths/Y
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17. Environmental factors
Alcohol : Excessive intake of alcoholic beverages is associated
with oesophageal and liver cancer.
Some recent studies have suggested that beer consumption may
be associated with rectal cancer .
It is estimated that alcohol contributed to about 3% of all
cancer deaths .
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18. Environmental factors
 Dietary factors are also related to cancer.
Smoked fish is related to stomach cancer, dietary fibre to
intestinal cancer, beef consumption to bowel cancer and a high
fat diet to breast cancer. A variety of other dietary factors such
as food additives and contaminants have fallen under suspicion
as causative agents
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19. Environmental factors
OCCUPATIONAL EXPOSURES :
 Exposure to benzene, arsenic, cadmium, chromium, vinyl
chloride, asbestos, polycyclic hydrocarbons, etc.
 Risk of occupational exposure is considerably increased with
smoke cigarettes.
 Occupational exposures are usually reported to account for 1 to
5% of all human cancers
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20. Environmental factors
Viruses :
 Hepatitis B and C virus is causally related to hepatocellular
carcinoma.
High RR of Kaposi's sarcoma occurring in patients with HIV .
Non-Hodgkin's lymphoma is a late complication of AIDS
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21. Environmental factors
 EBV is associated with 2 human malignancies, viz. Burkitt's
lymphoma and nasopharyngeal carcinoma.
 CMV is a suspected oncogenic agent and classical Kaposi's
sarcoma
HPV is a chief suspect in cancer cervix.
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22. Environmental factors
Parasitic infections may also increase the risk of cancer, as
for example, schistosomiasis in Middle East producing
carcinoma of the bladder
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23. Environmental factors
Customs, habits and lifestyles :
 Demonstrated Association Between Smoking and Lung Cancer,
Tobacco and Betel Chewing & Oral Cancer.
Others : There are numerous other environmental factors such as
sunlight, radiation , air and water pollution, medications (E.G.,
Oestrogen) and pesticides which are related to cancer.
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24. Genetic Factors
Retinoblastoma
 Mongols are more likely to develop cancer (leukaemia) .
 Genetic factors are less notifiable and more difficult to identify.
 There is probably a complex interrelationship between hereditary
susceptibility and environmental carcinogenic stimuli in the
causation of a number of cancers.
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25. Cancer Control
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26. 26
Levels of Prevention

27. 27

28. Level Phase of disease Aim Action target
Primary prevention Specific causal
factor
Reduce the
incidence
of disease
Protection of health by
personal and community
efforts, such as enhancing
nutritional status,
immunizations, eliminating
environmental risks.
Total population,
selected
groups and individuals
at
high-risk; achieved
through
public health
programmes
Secondary
prevention
Early stage of the
disease
Reduce the
prevalence
of disease by
shortening
its duration
Measures available to
individuals
and communities for early
detection and prompt
intervention
to control disease and
minimize
disability (e.g. through
screening programmes).
Individuals with
established
disease; achieved
through
early diagnosis and
treatment
Tertiary prevention Late stage of the
disease
Reduce the
number
and/or impact of
complication
Measures aimed at softening
the
impact of long-term disease
and
disability; minimizing
suffering; maximizing
potential years
Patients; achieved
through
rehabilitation

29. Primary prevention
1. Control of tobacco and alcohol consumption
2. Personal Hygiene: Improvements in personal hygiene may lead
to declines in the incidence of certain types of cancer, e.g. , Ca
cervix.
3. Radiation: Special efforts should be made to reduce the amount
of radiation (including medical radiation) received by each
individual to a minimum.
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30. Primary prevention
4. Occupational Exposures : Measures to protect workers from
exposure to industrial carcinogens should be enforced in
industries.
5. Immunization : immunization against hepatitis B virus and
for prevention of cancer cervix immunization against HPV
presents an exciting prospect.
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31. Primary prevention
6. Foods, Drugs And Cosmetics: These should be tested for
carcinogens.
7. Air Pollution : Control of air pollution
8. Legislation For example, legislation to control known
environmental carcinogens (e.g. , tobacco, alcohol , air pollution).
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32. Primary prevention
Cancer Education
 It should be directed at "high-risk" groups. The aim of cancer
education is to motivate people to seek early diagnosis and early
treatment.
 Remind the public of the early warning signs ("danger
signals") of cancer.
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33. Danger signals of cancer
1. lump or hard area in the breast
2. change in a wart or mole
3. persistent change in digestive and bowel habits
4. persistent cough or hoarseness
5. excessive loss of blood at the monthly period or loss of blood
outside the usual dates
6. blood loss from any natural orifice
7. swelling or sore that does not get better
8. unexplained loss of weight.
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34. Secondary Prevention
1. Cancer registration
2. Early detection of cases
3. Treatment
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35. Cancer Registration
 Mandatory for any cancer control programme.
It provides a base for assessing the magnitude of the problem and
for planning the necessary services.
 Cancer registries are basically of two types :
1. Hospital-based R
2. Population based R aim is to cover the complete cancer situation in a given
geographic area.
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36. Early Detection of Cases
Cancer screening is the main weapon for early detection of
cancer at a pre-invasive (in situ) or pre-malignant stage.
Effective screening programmes have been developed(Yemen?)
for Cx cancer, breast cancer and oral cancer.
 Early Dx has to be conducted on a large scale; however, it may
be possible to increase the efficiency of screening by focussing on
high-risk groups.
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37. Early Detection of Cases
There is no point in detecting cancer at an early stage unless
facilities for treatment and after-care are available.
Early detection programmes will require mobilization of all
available resources and development of a cancer infrastructure
starting at the level of primary health care, ending with complex
cancer centres or institutions at the state or national levels.
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38. Treatment
Treatment facilities should be available to all cancer patients.
 Surgical removal, while some others respond favourably to
Radiation or Chemotherapy or both.
Multi-modality approach to cancer control has become a
standard practice in cancer centres all over the world.
In the developed countries today, cancer treatment is geared to
high technology.
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39. Tertiary prevention
For those who are beyond the curable stage. The goal must be to
provide pain relief.
 A largely neglected problem in cancer care is the management of
pain.
The WHO has developed guidelines on relief of cancer pain .
"Freedom from cancer pain" is now considered a right of cancer
patients.
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40. Cancer Screening
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41. Screening for cancer cervix
Visual inspection based screening tests such as visual inspection
with 5 per cent acetic acid (VIA). visual inspection post application
of Lugol's iodine (VIL)
A periodic pelvic Ex& Pap smear(every 3 y or 5yr)
Colposcopy
 biopsy done to ensure the Dx
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42. Screening for breast cancer
1. Breast self-examination (BSE) by the patient
2. Palpation by a physician
3. Thermography not a sensitive tool.
4. Mammography (sensitive and specific)
500 milliroentgen compared to a 30-40 milliroentgen dose received in chest X-ray
Women under 35 years of age should not have X-rays unless they are symptomatic or a FH
of early onset of breast cancer
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43. Screening for lung cancer
1. chest radiograph
2. sputum cytology.
It is doubtful whether the disease satisfies the criteria of suitability for screening
??
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