Oncology 1
HC 1
1.1
Cancer is a group of genetic diseases characterized by unregulated cell growth and invasion,
along with the spreading of the cells from the site of origin, to distant sites in the body. It is
indeed a group of diseases, as there are several types of cancers, each with distinguishable
characteristics. Especially the site of origin is a classifying feature, with cancers arising in
epithelial tissues being termed carcinomas, those from mesodermal tissues sarcomas and
those from glandular tissues adenocarcinomas. Cancer arising from (progenitors) of white
blood cells are termed lymphomas. Each cancer has different risk factors and molecular
mechanisms, and thus requires different treatment options.
However, 10 hallmarks of cancer have been identified – characteristics all cancers share.
These include: angiogenesis, invasion/metastasis, tumor-promoting inflammation, unlimited
replicative potential, avoiding immune destruction, evasion of inhibitory signals, growth
signal autonomy, reprogramming of energy metabolism, evasion of cell death and lastly,
genome instability and mutation. Each hallmark poses as a new gateway for selective
therapy.
There furthermore ought to be a distinction between benign and malignant tumors. The
former is not evidence of cancer, as they do not spread throughout the body. They are still
dangerous as they may mechanically obstruct or increase pressure on certain organs.
Malignant tumors are examples of cancer, as these do not remain encapsulated, invade and
metastasize; they thereby compete with healthy cells for nutrients/oxygen, impair the
normal organ functioning and they may cause obstructions.
Some other definitions associated with cancers include:
- Incidence: the number of new cases that is registered within a certain time period.
This number appears to be increasing over the years, as the overall population is
ageing and there is better screening or diagnostics. The incidence of prostate (males)
and breast cancer (females) is highest.
- Prevalence: all people who somewhere in time have been diagnosed with cancer and
are still living at a certain date. These also include those that are cured.
- Mortality: the number of patients who died as a result of cancer within a certain
time period. Also this number is increasing lately, which is also due to the ageing
population – as is it due to the in general increasing population. Mortality numbers
change over the years because of lifestyle changes; men quit smoking but drink
more.
- Survival: the percentage of patients still living at a certain period after diagnosis. This
survival is corrected for the expected death within a population (specifying gender,
age and calendar year). Not all tumors, moreover, have the same survival curve.
1.2
Most agents that cause cancer, carcinogens, induce changes and alterations in the DNA
sequence of cells; mutations (mutagens). A large amount of evidence furthermore suggests
that cancer is a disease that arises from DNA mutations, ranging from subtle point
mutations to large chromosomal aberrations, like deletions and translocations. One
mutation however is not sufficient to directly change a normal cell into a tumor cell, an
HC 1
1.1
Cancer is a group of genetic diseases characterized by unregulated cell growth and invasion,
along with the spreading of the cells from the site of origin, to distant sites in the body. It is
indeed a group of diseases, as there are several types of cancers, each with distinguishable
characteristics. Especially the site of origin is a classifying feature, with cancers arising in
epithelial tissues being termed carcinomas, those from mesodermal tissues sarcomas and
those from glandular tissues adenocarcinomas. Cancer arising from (progenitors) of white
blood cells are termed lymphomas. Each cancer has different risk factors and molecular
mechanisms, and thus requires different treatment options.
However, 10 hallmarks of cancer have been identified – characteristics all cancers share.
These include: angiogenesis, invasion/metastasis, tumor-promoting inflammation, unlimited
replicative potential, avoiding immune destruction, evasion of inhibitory signals, growth
signal autonomy, reprogramming of energy metabolism, evasion of cell death and lastly,
genome instability and mutation. Each hallmark poses as a new gateway for selective
therapy.
There furthermore ought to be a distinction between benign and malignant tumors. The
former is not evidence of cancer, as they do not spread throughout the body. They are still
dangerous as they may mechanically obstruct or increase pressure on certain organs.
Malignant tumors are examples of cancer, as these do not remain encapsulated, invade and
metastasize; they thereby compete with healthy cells for nutrients/oxygen, impair the
normal organ functioning and they may cause obstructions.
Some other definitions associated with cancers include:
- Incidence: the number of new cases that is registered within a certain time period.
This number appears to be increasing over the years, as the overall population is
ageing and there is better screening or diagnostics. The incidence of prostate (males)
and breast cancer (females) is highest.
- Prevalence: all people who somewhere in time have been diagnosed with cancer and
are still living at a certain date. These also include those that are cured.
- Mortality: the number of patients who died as a result of cancer within a certain
time period. Also this number is increasing lately, which is also due to the ageing
population – as is it due to the in general increasing population. Mortality numbers
change over the years because of lifestyle changes; men quit smoking but drink
more.
- Survival: the percentage of patients still living at a certain period after diagnosis. This
survival is corrected for the expected death within a population (specifying gender,
age and calendar year). Not all tumors, moreover, have the same survival curve.
1.2
Most agents that cause cancer, carcinogens, induce changes and alterations in the DNA
sequence of cells; mutations (mutagens). A large amount of evidence furthermore suggests
that cancer is a disease that arises from DNA mutations, ranging from subtle point
mutations to large chromosomal aberrations, like deletions and translocations. One
mutation however is not sufficient to directly change a normal cell into a tumor cell, an
