Oncology
Lecture 1: Cancer epidemiology
Cancer epidemiology is a broad field.
Descriptive epidemiology: life-time risk in females is 38%. 1 in 3 females will develop cancer.
Life-time risk in men is 45%. 1 in 2 will develop cancer once in their lives.
The older you get the higher the risk you get to develop cancer. Around 128.000 persons are
diagnosed with cancer in the NL per year.
Why is it important?
• Knowledge about trends in incidence and survival-mortality after cancer
• Can be used to develop, implement and evaluate effective policies for cancer control
(e.g. cancer screening, preventive measures, education health care personnel,
planning care facilities)
Prevalence:
e.g. Prevalence in 2018 in the NL: number of newly diagnosed cancers in 2018 in the NL
Incidence:
E.g. incidence in the NL in 2008: number of newly cancer cases in the NL
- Number: absolute number of new cases in a certain period
- CR (crude rate): number of new cases per 100,000 persons per year
- ESR (European standardized rate): number of new cases per 100,000 persons per year,
standardized for the age composition of Europe
- WSR (World standardized rate): number of new cases per 100,000 persons per year,
standardized for the age composition of the world
Mortality:
e.g. mortality in 2018 in the NL: number of cases that died from cancer in 2018 in the NL. Also
expressed as number, CR, ESR, WSR (similar to incidence)
,The percentage of cancer cases alive at a certain time period after diagnosis (not including
those who died from other diseases) e.g. 5-year relative survival: Percentage of cancer cases
who survived 5 years
Western countries show higher percentages cancer. Reasons —> people live longer, different
lifestyles like food consumption, people in other countries might not be properly diagnosed.
More common cancer in females is breast cancer
and in males lung cancer. Stomach cancer is most
common in Asia due to helicobacter pylori and food
consumption. Also, liver cancer due to alcohol
consumption, hepatitis b and Aflatoxin (toxin in
peanuts). Cervix cancer is due to HPV and most
prevalent in Africa.
Mortality is decreasing over time in the NL due to
better screening and treatments. Lung cancer is the first one when it comes to mortality
because it spreads more and is more difficult to treat.
Etiologic cancer epidemiology: Age is the most important risk factor for cancer. Why? Time
needed for accumulation of damage to daughter cells. Mutations in regulatory genes:
- ‘Spontaneous’
- Chemical substances
- Radiation
- Viruses
Protective tools:
- Repair of blueprint (DNA repair)
- Clean suicide (apoptosis)
- Mitosis steps (senescence)
Cancer at older age
- Accumulation of damage / mutations in regulatory genes
- More damage to repair tools / repair tools less effective
- Less control by micro-environment
More people that are alive over 65 years —>
• +25% cancer diagnosis per year,
• survival has improved,
• +13% more deaths per year,
• +46% numbers of patients alive per year
Enormous public health problem:
- Double ageing phenomenon
- Better survival because of
- Early detection
- Improved treatment
—>More expensive health care (Diagnosis, treatment)
,Conclusion: Focus on prevention!!
How do you identify causes of cancer
• Accidental finding / keep alert
• Systematic counting / trends
• Focussed research (human observational studies, experimental studies)
• Exploration
Disadvantage: the information might not be really accurate especially from patients.
You get two groups: disease and no disease and you seek for differences in exposure.
Advantage compared to case control: you ask about the exposure before the development of
the disease. Less chance of recall bias.
Smoking is related to Cancer of the: Lung (95%!), Bladder (50%!), Stomach, Intestine,
Oesophagus, Mouth, Pancreas.But also: Cardiovascular diseases, Impotence. Risk is reduced
the earlier you stop with smoking.
Lifestyle-related risk factors for cancer
, Up to 33% of cancers could be prevented if you have a healthy lifestyle. Depends on cancer
type and country you are in.
Grading the evidence: Convincing
- Strong and unlikely to change in future
- No unexplained heterogeneity
- At least 2 independent cohort studies
- Good quality studies that account for error
- Dose response
- Robust evidence from laboratory studies
Grading the evidence: Probable
- No unexplained heterogeneity
- At least 2 independent cohort or 5 case-control studies
- Good quality studies that account for error
- Dose response
- Plausible evidence from laboratory studies
Obesity and alcohol may increase the risk of cancer. Physical activity may decrease it.
Randomized controlled trials
- Ethical?
- Lack of compliance
- Short duration
- Intermediate endpoints
- Timing of exposure
- Costly
Lecture 1: Cancer epidemiology
Cancer epidemiology is a broad field.
Descriptive epidemiology: life-time risk in females is 38%. 1 in 3 females will develop cancer.
Life-time risk in men is 45%. 1 in 2 will develop cancer once in their lives.
The older you get the higher the risk you get to develop cancer. Around 128.000 persons are
diagnosed with cancer in the NL per year.
Why is it important?
• Knowledge about trends in incidence and survival-mortality after cancer
• Can be used to develop, implement and evaluate effective policies for cancer control
(e.g. cancer screening, preventive measures, education health care personnel,
planning care facilities)
Prevalence:
e.g. Prevalence in 2018 in the NL: number of newly diagnosed cancers in 2018 in the NL
Incidence:
E.g. incidence in the NL in 2008: number of newly cancer cases in the NL
- Number: absolute number of new cases in a certain period
- CR (crude rate): number of new cases per 100,000 persons per year
- ESR (European standardized rate): number of new cases per 100,000 persons per year,
standardized for the age composition of Europe
- WSR (World standardized rate): number of new cases per 100,000 persons per year,
standardized for the age composition of the world
Mortality:
e.g. mortality in 2018 in the NL: number of cases that died from cancer in 2018 in the NL. Also
expressed as number, CR, ESR, WSR (similar to incidence)
,The percentage of cancer cases alive at a certain time period after diagnosis (not including
those who died from other diseases) e.g. 5-year relative survival: Percentage of cancer cases
who survived 5 years
Western countries show higher percentages cancer. Reasons —> people live longer, different
lifestyles like food consumption, people in other countries might not be properly diagnosed.
More common cancer in females is breast cancer
and in males lung cancer. Stomach cancer is most
common in Asia due to helicobacter pylori and food
consumption. Also, liver cancer due to alcohol
consumption, hepatitis b and Aflatoxin (toxin in
peanuts). Cervix cancer is due to HPV and most
prevalent in Africa.
Mortality is decreasing over time in the NL due to
better screening and treatments. Lung cancer is the first one when it comes to mortality
because it spreads more and is more difficult to treat.
Etiologic cancer epidemiology: Age is the most important risk factor for cancer. Why? Time
needed for accumulation of damage to daughter cells. Mutations in regulatory genes:
- ‘Spontaneous’
- Chemical substances
- Radiation
- Viruses
Protective tools:
- Repair of blueprint (DNA repair)
- Clean suicide (apoptosis)
- Mitosis steps (senescence)
Cancer at older age
- Accumulation of damage / mutations in regulatory genes
- More damage to repair tools / repair tools less effective
- Less control by micro-environment
More people that are alive over 65 years —>
• +25% cancer diagnosis per year,
• survival has improved,
• +13% more deaths per year,
• +46% numbers of patients alive per year
Enormous public health problem:
- Double ageing phenomenon
- Better survival because of
- Early detection
- Improved treatment
—>More expensive health care (Diagnosis, treatment)
,Conclusion: Focus on prevention!!
How do you identify causes of cancer
• Accidental finding / keep alert
• Systematic counting / trends
• Focussed research (human observational studies, experimental studies)
• Exploration
Disadvantage: the information might not be really accurate especially from patients.
You get two groups: disease and no disease and you seek for differences in exposure.
Advantage compared to case control: you ask about the exposure before the development of
the disease. Less chance of recall bias.
Smoking is related to Cancer of the: Lung (95%!), Bladder (50%!), Stomach, Intestine,
Oesophagus, Mouth, Pancreas.But also: Cardiovascular diseases, Impotence. Risk is reduced
the earlier you stop with smoking.
Lifestyle-related risk factors for cancer
, Up to 33% of cancers could be prevented if you have a healthy lifestyle. Depends on cancer
type and country you are in.
Grading the evidence: Convincing
- Strong and unlikely to change in future
- No unexplained heterogeneity
- At least 2 independent cohort studies
- Good quality studies that account for error
- Dose response
- Robust evidence from laboratory studies
Grading the evidence: Probable
- No unexplained heterogeneity
- At least 2 independent cohort or 5 case-control studies
- Good quality studies that account for error
- Dose response
- Plausible evidence from laboratory studies
Obesity and alcohol may increase the risk of cancer. Physical activity may decrease it.
Randomized controlled trials
- Ethical?
- Lack of compliance
- Short duration
- Intermediate endpoints
- Timing of exposure
- Costly
