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All lectures of the course Oncology
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This document contains all the lectures from the course Oncology.
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Oncology – LecturesLecture 1;
Question: what is the life-time risk (85 yrs) of cancer in females?
- 38% (more than 1 in 3 females)
Question: what is life-time risk (85 yrs) of cancer in males?
- 45% (almost 1 in 2 males) → more males smoke, and recently they found that males get
more cancer because they have genetic differences
The risk in both males and females differs with different kinds of cancer. Female have more chance
of getting breast cancer, while for males getting prostate cancer is highest.
Why is cancer epidemiology important? → knowledge about trends in incidence and
survival/mortality after cancer to;
- Make informed decisions regarding health policy
- Adequately evaluate clinical developments
Key epidemiological concepts:
- Prevalence
- Incidence
- Mortality
- Relative survival
Prevalence= # of people with cancer / population at risk (at a certain moment in time)
e.g. 5 year prevalence at 1 january 2019 in the NL: all living cancer patients who have been diagnosed
in the previous 5 years in the NL.
Incidence= # of newly diagnosed cases of cancer / population at risk (in a certain time period)
e.g. incidence in 2018 in the NL: number of newly diagnosed cancer cases in 2018 in the NL
- 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= # of cases that died from cancer / population at risk (in a certain time period)
e.g. mortality in 2018 in the NL: number of cases that died from cancer in 2018 in the NL (also
expressed as CR, ESR, WSR (similar to incidence))
Relative survival= 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
Question: how many persons are diagnosed with (invasive) cancer every year in the Netherlands? →
about 118.000
The relative mortality total cancer in NL is decreasing, this is because it is diagnosed earlier and the
treatment of cancer is already much better
Lung cancer is the most important cause of death for both males and females.
Question: what is the most important risk factor for cancer in general? → Age
With increasing age the number of diagnoses is increasing.
,Why age?; time needed for accumulation of damage to daughter cells. Mutations in regulatory
genes: spontaneous, chemical substances, radiation, viruses (the longer you are exposed to these
substances, the more change of getting mutations/cancer)
Protective tools:
- Repair of blueprint (DNA repair)
- Clean suicide (apoptosis)
- Mitosis stops (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
Enormous public health problem;
- Double ageing phenomenon
- Better survival because of;
o Early detection
o Improved treatment
- More expensive health care;
o Diagnosis
o Treatment
➔ Conclusion: focus on prevention
How do you identify causes of cancer?
- Accidental finding / keep alert
- Systematic counting / trends
- Focussed research
o Human observational
o Model experimental
- Exploration
Accidental finding → in 1713 a researcher found that nuns have more changes of getting breast
cancer (they do not have children, are not sexually active) → so conclusion is that it is depending on
hormones. Having no children or having an early cycle / menopause increases the risk of getting
breast cancer
Systemic counting / trends → for example following people who moved from Japan to USA, then the
researchers saw that the stomach cancer is decreasing per generation, while breast cancer is
increasing.
The melanoma cancer increased a lot first, but then sunscreen was promoted and there was/is a
drop of melanoma cancer
Focussed research →
Do a case-control study. This is to see if there
are differences in risk factors between cases
and control that may be related to the disease
, this is a prospective cohort study. Here you start
with all healthy individuals and you use mostly
questionnaires to ask questions about smoking or
something like that. And then you compare the
ones that are exposed to a certain risk factor and
those that are not.
Question: which % of cancers can be prevented by a healthy diet, body weight and physical activity?
→ 33%
Grading the evidence:
- Convincing
- Probable
- Limited evidence – suggestive
- Limited evidence – no conclusion
- Substantial effect on risk unlikely
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
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
Population attributable (preventable) fraction (PAF)
- PAF= p(RR – 1) / p(RR – 1) + 1
RR= relative risk of disease for the risk factor
p= prevalence (proportion) of the risk factor in the population
Randomized controlled trials;
- Ethical ?
- Lack of compliance
- Short duration
- Intermediate endpoints
- Timing of exposure
- Costly
Conclusions: do not smoke, avoid overweight, be
active and eat healthy
, Not only life style is influencing the risk of cancer, but also biological, social and physical
environment.
Only 5-10% of the cancer is inherited, and 90% is because of gene-environment interactions
Lecture 2
Point mutations, intrachromosomal rearrangement and copy-number change can happen that then
causes cancer
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