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Hallmarks of Cancer
The name cancer is from the ancient Greek word for crab – karkinos
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But, for the first time ever the number
of people dying from cancer is equal to the number of people surviving cancer
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Chemotherapy is only effective in 25% of cancer cases
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) may
lead to a higher percentage of people surviving
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Chemotherapy
Chemotherapy is a broad name for a collection of drugs with various different
mechanisms of action
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 Inhibitors of DNA synthesis
o Alkylating Agents and Platinum Based Drugs
o Antimetabolites
 Inhibitors of microtubule formation
 Hormones
 Organic Drugs
Radiotherapy
Radiotherapy uses radiation to produce Reactive Oxygen Species inside cells
that cause extensive damage to DNA – this will result in the death of the cell
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E
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The radiation may cause more
tumour formation by damaging healthy cells
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There are over 200 different types
of cancer
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An uncontrollable proliferation of cells
2
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Cancer cells usually travel in blood vessels or through the lymphatic
system
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Examples of benign tumours include
moles and warts – these are abnormalities but they don’t metastasis
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Types of Cancer
Carcinomas – originate from cells that cover external and internal body
surfaces
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Sarcomas – cancer arising from cells in the supporting tissues such as bine,
cartilage, fat, connective tissue and muscle
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Leukaemias – cancers of the immature blood cells that grow in the bone
marrow and are found in large numbers in the blood stream
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For example, skin
cancer can be caused by UV radiation, ionising radiation, polycyclic aromatic
hydrocarbons
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Ionising radiation can cause
myeloid leukaemia, osteosarcoma (bone cancer), thyroid cancer, skin cancer or
breast cancer
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Age, UV exposure, skin
pigmentation and DNA repair capacity
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Numerous chemicals have been linked to causing cancer
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It was found to be caused by carbon particles found in the
chimney soot
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This cancer has a very long lag phase
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Malignant Transformation – Cancer Progression
Cancer develops in cells via a stepwise accumulation of mutations
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There are three types of ‘cancer genes’:
1
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Mutation turns these genes “on”
b
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Tumour Suppressor Genes
a
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Turns the ‘brakes’ of division off
3
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Mutation turns these genes “off”
Radiation
Hiroshima 6th August 1945
70,000 killed by the initial nuclear blast
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Leukaemia and solid tumours were some
of the most frequently reported cancers
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Heredity
Some cancers have been found to be a case of ‘bad luck’ while some have been
found to have heredity links
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These are tumour
suppressor genes and are involved in repairing DNA damage
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There is strong evidence to support this:

Average Population
Risk
BRCA1/BRCA2
mutation

% Chance of Developing Breast Cancer
By Age 40
By Age 50
By Age 70
0
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Angelina Jolie is a recent and
well known example
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The hormone diethylstilbestrol was prescribed to women between 1940 and
1971 to prevent miscarriage
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Androgens (anabolic steroid e
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testosterone) are linked to prostate cancer
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These hormones are considered initiators of cancer because they increase the
proliferative capacity of target tissues
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Some breast cancer
patients receive anti-oestrogen therapy
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Recently, the World
Health Organisation has put processed and red meats in the same group as
tobacco as ‘cancer causing’
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Obesity in women has been linked to an increased risk of breast cancer (in
older women), endometrial kidney, colon, and oesophagus cancer
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Morphology of Cancer Cells
 Cancer cells can grow indefinitely in culture
o Henrietta Lacks died of cancer in October 1951
o Her cells are used all over the world for research
o They divide once every 24 hours – strongest cells known to
science
 They can pile up on each other
o No contact inhibition
 They can have multiple nuclei
 The chromosome number and structure can be abnormal
The overall morphology of a cancer cell can be completely different to that of
its parent
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The grade of the cancer (I-IV) is determined by the morphology of the cancer
cells – i
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how the cell looks under a microscope
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A patient’s chance for survival is better if the cancer is at a lower
stage
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Deregulation is a result of
genetic changes that confer a growth advantage to the cell
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A cell returning to mitosis does so at early G1
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’ This is where the
eukaryotic cell spends the majority of its life
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Interphase can be split into 3 sub phases:
1
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b
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d
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S
a
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Also known as the Swanson phase
3
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Cell resumes its growth in preparation for division
The duration of time spent in interphase and in each sub phase is variable and
depends on the cell type and the species that the organism belongs to
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Prophase
This is the first stage of mitosis
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Major problems occur here in cancer
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Cyclin/Cdk Complexes
These complexes are key regulators of the cell cycle – activation of a given
kinase activates the proteins required for progression from one stage of the
cell cycle to the next
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They are then degraded usually by
ubiquitination – this is a signal for production of another cyclin and a signal for
the cell to progress into the next step of the cell cycle
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Apoptosis
Apoptosis is the highly regulated method of programmed cell death
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Extrinsic causes of apoptosis is caused by the death ligand and the death
receptor which is mediated by caspase 3
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Mitochondria play a critical role in apoptosis as
shown opposite
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Cytochrome C (CytC) is released from
the mitochondria, among other proteins, which
ultimately causes death of the cell by apoptosis

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