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ISLAMIC MEDICAL EDUCATION RESOURCES01

9711-EPIDEMIOLOGY OF CANCER

Lecture to 1st year students, Kulliyah of Medicine, International Islamic University, Kuantan on 14th November 1997 by Prof Dr Omar Hasan Kasule, Sr. Deputy Dean for Research and Post-graduate Affairs

OUTLINE

INTRODUCTION

HISTORY OF CANCER EPIDEMIOLOGY

DESCRIPTIVE EPIDEMIOLOGY OF CANCER

PURPOSES OF DESCRIPTIVE EPIDEMIOLOGY

MEASUREMENT OF CANCER

TRENDS OF CANCER

TYPES OF CANCER DATA

SOURCES OF DATA ON CANCER

METHODS OF CANCER EPIDEMIOLOGY

ENVIRONMENTAL RISK FACTORS

 

INTRODUCTION

Cancer Epidemiology deals with the distribution, determinants (causes) and prevention of cancer. It also extends to deal with aspects of cancer treatment. Epidemiology being a quantitative medical science deals with numbers and figures.

 

Cancer is not one disease. It is many diseases each with its risk factors and different methods of treatment and prevention.

 

Cancer is a global problem affecting all countries of the world and all humans irrespective of ethnicity, age, and socio-economic status

 

 

HISTORY OF CANCER EPIDEMIOLOGY

1713:               Ramazzini recorded high cancer in nuns (nulliparous)

18th century      Hill observed cancer of the nose in snuff users

18th century      Soemmering observed cancer of the lower lip in pipe

                        smokers

?                      Percival Pott recorded high cancer of the scrotum in

                        chimney sweeps

1895:               Bladder cancer associated with work in the dye stuff

                        industry

1956                Smoking and lung cancer among British doctors

 

DESCRIPTIVE EPIDEMIOLOGY OF CANCER

Geographical variation

Ethnic/racial variation

Socio-economic variation

Socio-cultural variation

Age distribution

Sex distribution

Time trends

Migratory patterns

Site distribution

 

PURPOSES OF DESCRIPTIVE EPIDEMIOLOGY

Understand the public health impact of cancer

Study how cancer burden varies from place to place

Understand temporal changes and trends

Get clues about causation and avoidability

 

MEASUREMENT OF CANCER

Incidence

Prevalence (cancer burden)

Mortality

Survival

 

TRENDS OF CANCER

There are approximately 8 million new cases of cancer a year. With the decrease of infectious diseases, increasing life-spans in all countries of the world in addition to increasing exposure to environmental and industrial cancer risk factors, incidence and mortality due to cancer are increasing as a proportion of total morbidity and mortality. 

 

TYPES OF CANCER DATA

Epidemiological

Laboratory (biological, pathological, chemical, molecular)

Clinical

Environmental

 

SOURCES OF DATA ON CANCER

National or Regional Cancer Registries

Death Certificate Data

Hospital Records

Special Surveys and Studies

 

 METHODS OF CANCER EPIDEMIOLOGY

DESCRIPTIVE

Incidence

Prevalence

 

ANALYTIC

Causal association

Prospective and retrospective

Correlation

Migratory studies

 

INTERVENTION

Primary prevention

Diet

Environment

Education

Control infections

Secondary prevention

Tertiary prevention

           

PREVENTION

Epidemiological data used to prevent cancer even without knowing the exact cause(s)

Epidemiology helps cancer prevention by manipulation of exposure to environmental exposures and life-style

Education

Intervention

Screening for early detection

Prevention strategies for given cancers

Lung                 stop smoking, new cigarettes, diet

Mouth              stop quid smoking, stop tobacco chewing

Liver                HBV immunisation, aflatoxin

Cervix              genital hygiene, sexual behaviour

ENVIRONMENTAL RISK FACTORS

Time of exposure

Duration of exposure

Age at exposure

Identified risk factors

Tobacco

Occupation

Radiation

Alcohol

Diet

Drugs

Reproductive Factors

Air Pollution

Microbial agents

 

TREATMENT OF CANCER

Strategies

Curative eg BL, leukemia

Supportive

Treatment modalities

Surgery

Chemotherapy

Irradiation

Immunotherapy

 

LIFE-TIME CANCER RISK: PROBABILITY OF DEVELOPING CANCER WITHIN SPECIFIED PERIODS OF TIME BY PERSONS AT SELECTED AGES PREVIOUSLY UNDIAGNOSED WITH CANCER OF THAT SITE BY RACE AND SEX US 1970

 

SEX     RACE                          AGE 20                                   AGE 50                      

                                    10 yrs   20 yrs   Eventually         10 yrs   20 yrs   Eventually

 

Male    White               0.33%  0.90%  26.87%                        4.93%  13.91%            27.12%

            Non-White       0.24%  0.82%  24.49%                        6.48%  15.55%            27.48%

 

Female White               0.41%  1.53%  27.84%                        5.50%  12.64%            27.48%

            Non-White       0.48%  1.79%  22.21%                        4.94%  11.00%            20.37%

 

 

Adapted from: Seidman et al. Probabilities of Eventually Developing and Dying of Cancer. CA 28:33-44, 1978

 

CANCER ADMISSIONS & DEATHS IN MALAYSIA 1989-1993

 

 

 

ESTIMATED NEW CANCER CASES AND DEATHS BY SEX FOR ALL SITES, US 1995

 

LEADING SITES OF NEW CANCER CASES AND DEATHS, 1995

 

CANCER DEATH RATES BY SITE FOR MALES, US 1930-91

 

CANCER DEATH RATES BY SITE FOR FEMALES, US 1930-91

 

CANCER AROUND THE WORLD, 1988-1991, DEATH RATES PER 100,000 POPULATION FOR 46 COUNTRIES

 

BASIC TERMINOLOGY OF CANCER BIOLOGY

Hyperplasia is increase in the number of cells

Dysplasia is a reversible regressive change in cells marked by variation in size, shape, and orientation

Anaplasia is irreversible change toward lesser differentiation

Tumor or neoplasm is an autonomous new tissue

Benign tumor is non-invading. Non-metastasising and slow-growing

Malignant Tumor is the opposite of benign

Cancer is a malignant neoplasm

Grade refers to the degree of histological differentiation of a tunor

Primary tunor is one that is contigous with the site of origin

Metastatic or secondary tumor is one that originates from a previously existing, anatomically separate tumor

Stage is the degree to which a tumor extends beyond its site of origin. In-situ is entirely confined to the tissue of origin. Localised is confined to the organ of origin. Regional is confined to tissue adjacent to the organ of origin including regional lymph nodes. Distant extends beyond the bounds of the regional

Carcinoma is a malignant neoplasm of epithelial cells, It can be epidermoid or squamous cell carcinoma, transitional cell carcinoma, or an adenocarcinoma. Most of cancers are epithelial

Sarcoma is a malignant neoplasm of connective tissue

Lymphoma. Myeloma, and leukemias are malignant neoplasms of hematopoietic cells

Initiation is an irreversible alteration in a tissue induced by exposure to a carcinonogen. Irradiation is an example of an initiator

Promotion is a process in which a initiated tissue is selectively stimulated to develop focal proliferation. Saccharin is an example of a promoter

Progression is the process by which initiated/promoted cells turn into cancer. Estrogens are an example of a progression agent

Induction period

latent period

 

INTRODUCTION

 

Cancer Epidemiology deals with the distribution, determinants (causes) and prevention of cancer. It also extends to deal with aspects of cancer treatment. Epidemiology being a quantitative medical science deals with numbers and figures.

 

Cancer is not one disease. It is many diseases each with its risk factors and different methods of treatment and prevention.

 

Cancer is a global problem affecting all countries of the world and all humans irrespective of ethnicity, age, and socio-economic status

 

HISTORY OF CANCER EPIDEMIOLOGY

 

1713:               Ramazzini recorded high cancer in nuns (nulliparous)

 

18th century      Hill observed cancer of the nose in snuff users

 

18th century      Soemmering observed cancer of the lower lip in pipe

                         -smokers

 

?                                  Percival Pott recorded high cancer of the scrotum in

                         chimney sweeps

 

1895:               Bladder cancer associated with work in the dye stuff

                         industry

 

1956                Smoking and lung cancer among British doctors

 

 

DESCRIPTIVE EPIDEMIOLOGY OF CANCER

 

Geographical variation

 

Ethnic/racial variation

 

Socio-economic variation

 

Socio-cultural variation

 

Age distribution

 

Sex distribution

 

Time trends

 

Migratory patterns

 

Site distribution


PURPOSES OF DESCRIPTIVE EPIDEMIOLOGY

 

Understand the public health impact of cancer

 

Study how cancer burden varies from place to place

 

Understand temporal changes and trends

 

Get clues about causation and avoidability

 

MEASUREMENT OF CANCER

 

Incidence

 

Prevalence (cancer burden)

 

Mortality

 

Survival

 

TRENDS OF CANCER

 

There are approximately 8 million new cases of cancer a year

 

With the decrease of infectious diseases, increasing life-spans in all countries of the world in addition to increasing exposure to environmental and industrial cancer risk factors, incidence and mortality due to cancer are increasing as a proportion of total morbidity and mortality. 

 

TYPES OF CANCER DATA

 

Epidemiological

 

Laboratory (biological, pathological, chemical, molecular)

 

Clinical

 

Environmental

 

 

SOURCES OF DATA ON CANCER

 

National or Regional Cancer Registries

 

Death Certificate Data

 

Hospital Records

 

Special Surveys and Studies

 

METHODS OF CANCER EPIDEMIOLOGY

 

DESCRIPTIVE

Incidence

Prevalence

 

ANALYTIC

Causal association

Prospective and retrospective

Correlation

Migratory studies

 

INTERVENTION

Primary prevention

Diet

Environment

Education

Control infections

 

Secondary prevention

 

 

Tertiary prevention

           

PREVENTION

Epidemiological data used to prevent cancer even without knowing the exact cause(s)

 

Epidemiology helps cancer prevention by manipulation of exposure to environmental exposures and life-style

 

Education

 

Intervention

 

Screening for early detection

 

Prevention strategies for given cancers

Lung                 stop smoking, new cigarettes, diet

Mouth              stop quid smoking, stop tobacco chewing

Liver                HBV immunisation, aflatoxin

Cervix              genital hygiene, sexual behaviour

 


ENVIRONMENTAL RISK FACTORS

 

Time of exposure

 

Duration of exposure

 

Age at exposure

 

Identified risk factors

Tobacco

Occupation

Radiation

Alcohol

Diet

Drugs

Reproductive Factors

Air Pollution

Microbial agents

 

TREATMENT OF CANCER

 

Strategies

Curative eg BL, leukemia

Supportive

           

Treatment modalities

Surgery

Chemotherapy

Irradiation

Immunotherapy

 

LIFE-TIME CANCER RISK: PROBABILITY OF DEVELOPING CANCER WITHIN SPECIFIED PERIODS OF TIME BY PERSONS AT SELECTED AGES PREVIOUSLY UNDIAGNOSED WITH CANCER OF THAT SITE BY RACE AND SEX US 1970

 

SEX     RACE                          AGE 20                                   AGE 50                      

                                    10 yrs   20 yrs   Eventually         10 yrs   20 yrs   Eventually

 

Male    White               0.33%  0.90%  26.87%                        4.93%  13.91%            27.12%

            Non-White       0.24%  0.82%  24.49%                        6.48%  15.55%            27.48%

 

Female White               0.41%  1.53%  27.84%                        5.50%  12.64%            27.48%

            Non-White       0.48%  1.79%  22.21%                        4.94%  11.00%            20.37%

 

 

Adapted from: Seidman et al. Probabilities of Eventually Developing and Dying of Cancer. CA 28:33-44, 1978

 

CANCER ADMISSIONS & DEATHS MORTALITY IN MALAYSIA 1989-1993

 

ESTIMATED NEW CANCER CASES AND DEATHS BY SEX FOR ALL SITES, US 1995

 

LEADING SITES OF NEW CANCER CASES AND DEATHS, 1995

 

CANCER DEATH RATES BY SITE FOR MALES, US 1930-91

 

CANCER DEATH RATES BY SITE FOR FEMALES, US 1930-91

 

CANCER AROUND THE WORLD, 1988-1991, DEATH RATES PER 100,000 POPULATION FOR 46 COUNTRIES

 

BASIC TERMINOLOGY OF CANCER BIOLOGY

Hyperplasia is increase in the number of cells

Dysplasia is a reversible regressive change in cells marked by variation in size, shape, and orientation

Anaplasia is irreversible change toward lesser differentiation

Tumor or neoplasm is an autonomous new tissue

Benign tumor is non-invading. Non-metastasising and slow-growing

Malignant Tumor is the opposite of benign

Cancer is a malignant neoplasm

Grade refers to the degree of histological differentiation of a tunor

Primary tunor is one that is contigous with the site of origin

Metastatic or secondary tumor is one that originates from a previously existing, anatomically separate tumor

Stage is the degree to which a tumor extends beyond its site of origin. In-situ is entirely confined to the tissue of origin. Localised is confined to the organ of origin. Regional is confined to tissue adjacent to the organ of origin including regional lymph nodes. Distant extends beyond the bounds of the regional

Carcinoma is a malignant neoplasm of epithelial cells, It can be epidermoid or squamous cell carcinoma, transitional cell carcinoma, or an adenocarcinoma. Most of cancers are epithelial

Sarcoma is a malignant neoplasm of connective tissue

Lymphoma. Myeloma, and leukemias are malignant neoplasms of hematopoietic cells

Initiation is an irreversible alteration in a tissue induced by exposure to a carcinonogen. Irradiation is an example of an initiator

Promotion is a process in which a initiated tissue is selectively stimulated to develop focal proliferation. Saccharin is an example of a promoter

Progression is the process by which initiated/promoted cells turn into cancer. Estrogens are an example of a progression agent

Induction period

latent period

Professor Omar Hasan Kasule November 1997