Summary Oncology
Chapter 1, Introduction – The nature of cancer
Definitions
Incidence
The incidence of cancer is defined to be the number of new cases that is registered within a
certain period (mostly 1 year). To be able to follow the incidence in time, or to enable
comparison between regions, the incidence is mostly expressed as the number of new cases
per 100.000 inhabitants/persons each year: the crude incidence rate.
Prevalence
The prevalence of cancer comprises all persons who somewhere in time have been
diagnosed with cancer; and are still living at a certain date. Hence, this is a diverse group,
ranging from persons who have been cured from cancer in the past to persons who just have
been diagnosed with cancer. The period can be unlimited, but also defined. As an example:
the 5-year prevalence on January 1st, 2020, comprises all still living people who have been
diagnosed with cancer since January 1st, 2015.
Mortality
The mortality of cancer comprises the number of patients who died as a result of cancer
within a certain period (mostly 1 year).
Survival
Survival is the percentage of patients still living at a certain period after diagnosis. The
presented survival is a relative survival that approaches the “cancer-specific survival”. This
means that the survival observed is corrected for the expected death within a comparable
population (with respect to country/region, gender, age and calendar year).
Cancer incidence
How many new patients were diagnosed with cancer in The Netherlands in 2021?
Increase in incidence of cancer over the years. The dip in the graph indicates COVID as at
that time people went less to the GP.
• 5-year cancer prevalence (2022): ~390.000
• Mortality (2021): ~46.000 (The mortality of cancer has in the last 5 years not increased)
,Survival in time
as function of time after diagnosis, per decade (1961-2020)
Every decade the percentage of survival increased. Thus, we are improving the treatments.
Cancer incidence and mortality per tumor type
What can we conclude from this overview?
Blue= incidence; red= mortality
- Note that cancer is more common (with higher incidence) in high-income countries,
as people get older and the diagnosis is better developed.
- Some cancers can be cured (thyroid) as other have high mortality (lung)
Regional differences in cancer mortality
Top ranking of cancer as leading couse of premature death partly reflects marked declines in
mortality rates of stroke and coronary heart disease in many countries.
,Cancer mortality trends: 2010 vs 2000
Some striking differences, why?
- Mortality as a result of smoking increased in women while it decreased in males
(women started smoking later while some males already stopped smoking)
- Melanoma mortality increased (more common to go on vacation)
What is cancer? What is the clinical definition of cancer?
- Cancer is a group of diseases
- More than 100 cancer types can be distinguished
- Uncontrolled cell growth
- Invasive and forming metastases
Does a patient with a tumour always have cancer? NO
• A tumor is a mass of cells.
• Not every tumor is invasive and metastasising.
• Benign tumors are no cancer, only malignant tumors are cancer.
Why is a malignant tumour life-threatening?
- Invasion of organs disturbs organ function
- Cancer cells compete with normal cells for nutrients and oxygen
- Growing tumours can cause obstructions
What is the difference between carcinoma, adenocarcinoma, sarcoma and lymphoma?
• Carcinomas arise from epithelia (~85% of all cancers).
• Adenocarcinomas arise from glandular tissues (e.g breast).
• Sarcomas arise from mesodermal tissues (e.g. bone, muscle).
• Lymphomas arise from (progenitors of) white blood cells.
Why is the incidence of carcinomas much higher than other cancers?
• Carcinomas are derived from epithelial cells.
• Epithelial cells align our body (inside and outside) (they align your body and therefore
encounter damage often)
• Epithelial cells are most exposed to carcinogens
, Carcinogens
• A carcinogen is an agent causing cancer (compound, radiation, etc.).
• A carcinogen causes alterations in the DNA of a cell. (chapter 2)
• Cancer cells contain many alterations in the DNA.
• The accumulation of mutations in the DNA of a cell causes stepwise development of cancer
(oncogenesis, carcinogenesis).
Development of cancer (oncogenesis)
Multiple accumulations of mutation: First a single mutation and when it proliferates there
will be more mutations but they will all contain the first mutation (Clonal). But are
heterogenous as they contain multiple different mutations.
Cancer is therefore always clonal and heterogenous.
Is cancer inheritable?
• No. Almost all of the mutations develop in somatic cells and will not be passed to the next
generation of offspring.
• However, some inherited germline mutations can increase the chance to develop cancer
and can be passed on to the next generation of offspring. These mutations are rarely
involved in causing cancer immediately. (chapter 6)
Why does the risk to develop cancer increase at older age?
• An accumulation of mutations in the DNA is needed for the development of cancer.
• It is a matter of chance and time (exposure to carcinogens).
• The incidence of cancer is increasing due to longer life expectancy.
Chapter 1, Introduction – The nature of cancer
Definitions
Incidence
The incidence of cancer is defined to be the number of new cases that is registered within a
certain period (mostly 1 year). To be able to follow the incidence in time, or to enable
comparison between regions, the incidence is mostly expressed as the number of new cases
per 100.000 inhabitants/persons each year: the crude incidence rate.
Prevalence
The prevalence of cancer comprises all persons who somewhere in time have been
diagnosed with cancer; and are still living at a certain date. Hence, this is a diverse group,
ranging from persons who have been cured from cancer in the past to persons who just have
been diagnosed with cancer. The period can be unlimited, but also defined. As an example:
the 5-year prevalence on January 1st, 2020, comprises all still living people who have been
diagnosed with cancer since January 1st, 2015.
Mortality
The mortality of cancer comprises the number of patients who died as a result of cancer
within a certain period (mostly 1 year).
Survival
Survival is the percentage of patients still living at a certain period after diagnosis. The
presented survival is a relative survival that approaches the “cancer-specific survival”. This
means that the survival observed is corrected for the expected death within a comparable
population (with respect to country/region, gender, age and calendar year).
Cancer incidence
How many new patients were diagnosed with cancer in The Netherlands in 2021?
Increase in incidence of cancer over the years. The dip in the graph indicates COVID as at
that time people went less to the GP.
• 5-year cancer prevalence (2022): ~390.000
• Mortality (2021): ~46.000 (The mortality of cancer has in the last 5 years not increased)
,Survival in time
as function of time after diagnosis, per decade (1961-2020)
Every decade the percentage of survival increased. Thus, we are improving the treatments.
Cancer incidence and mortality per tumor type
What can we conclude from this overview?
Blue= incidence; red= mortality
- Note that cancer is more common (with higher incidence) in high-income countries,
as people get older and the diagnosis is better developed.
- Some cancers can be cured (thyroid) as other have high mortality (lung)
Regional differences in cancer mortality
Top ranking of cancer as leading couse of premature death partly reflects marked declines in
mortality rates of stroke and coronary heart disease in many countries.
,Cancer mortality trends: 2010 vs 2000
Some striking differences, why?
- Mortality as a result of smoking increased in women while it decreased in males
(women started smoking later while some males already stopped smoking)
- Melanoma mortality increased (more common to go on vacation)
What is cancer? What is the clinical definition of cancer?
- Cancer is a group of diseases
- More than 100 cancer types can be distinguished
- Uncontrolled cell growth
- Invasive and forming metastases
Does a patient with a tumour always have cancer? NO
• A tumor is a mass of cells.
• Not every tumor is invasive and metastasising.
• Benign tumors are no cancer, only malignant tumors are cancer.
Why is a malignant tumour life-threatening?
- Invasion of organs disturbs organ function
- Cancer cells compete with normal cells for nutrients and oxygen
- Growing tumours can cause obstructions
What is the difference between carcinoma, adenocarcinoma, sarcoma and lymphoma?
• Carcinomas arise from epithelia (~85% of all cancers).
• Adenocarcinomas arise from glandular tissues (e.g breast).
• Sarcomas arise from mesodermal tissues (e.g. bone, muscle).
• Lymphomas arise from (progenitors of) white blood cells.
Why is the incidence of carcinomas much higher than other cancers?
• Carcinomas are derived from epithelial cells.
• Epithelial cells align our body (inside and outside) (they align your body and therefore
encounter damage often)
• Epithelial cells are most exposed to carcinogens
, Carcinogens
• A carcinogen is an agent causing cancer (compound, radiation, etc.).
• A carcinogen causes alterations in the DNA of a cell. (chapter 2)
• Cancer cells contain many alterations in the DNA.
• The accumulation of mutations in the DNA of a cell causes stepwise development of cancer
(oncogenesis, carcinogenesis).
Development of cancer (oncogenesis)
Multiple accumulations of mutation: First a single mutation and when it proliferates there
will be more mutations but they will all contain the first mutation (Clonal). But are
heterogenous as they contain multiple different mutations.
Cancer is therefore always clonal and heterogenous.
Is cancer inheritable?
• No. Almost all of the mutations develop in somatic cells and will not be passed to the next
generation of offspring.
• However, some inherited germline mutations can increase the chance to develop cancer
and can be passed on to the next generation of offspring. These mutations are rarely
involved in causing cancer immediately. (chapter 6)
Why does the risk to develop cancer increase at older age?
• An accumulation of mutations in the DNA is needed for the development of cancer.
• It is a matter of chance and time (exposure to carcinogens).
• The incidence of cancer is increasing due to longer life expectancy.
