Cancer

Question 1

What is cancer?

Answer 1

Cancer is the uncontrolled cell division and proliferation of a group of cells
within, the body. These are altered cells which lack in some way the normal
constraints on cell division

Question 2

What are tumours?

Answer 2

Enlarged groups of cells, being either benign or malignant.

Question 3

What are benign tumours?

Answer 3

Benign
tumours, usually slow growing masses of tissue that compress rather than
invade surrounding tissues; they are not cancerous in that they do not invade
other areas of the body; however they can cause problems in that they can
occupy space that other tissues should be in

Question 4

What are malignant tumours?

Answer 4

Malignant tumours are cancerous, they invade nearby tissues initially then can
spread throughout the body; when they spread to other areas of the body they
are referred to as metastases. They are generally fast growing, rapidly invade
surrounding tissue and extensively colonise distant organs often distributed
through the lymphatic system and lymph nodes. The original site of the cancer
is referred to as the primary, the colonisation of distant sites are secondaries

Question 5

What is a carcinoma?

Answer 5

Carcinoma’s are cancers derived from epithelial tissues and are the most
common cancers for example breast, colon and lung cancer.

Question 6

What are sarcoma’s?

Answer 6

Sarcoma’s are cancers from mesenchymal cell origin – connective tissue,
bone and muscle, these are much more rare in humans as primary cancers.

Question 7

What are lymphoma’s?

Answer 7

Lymphoma’s usually originate in bone marrow and are due to the abnormal
development of white blood cells, hence the name

Question 8

What are the steps in the development of cancer?

Answer 8

Normal cell –> Persistent genetic damage –> somatic change –> Tumour formation –> vascularisation –> invasiveness –> Metatasis

Question 9

What happens when cells develop genetic damage?

Answer 9

You start with
normal cells to start and for some reason these normal cells develop a degree
of genetic damage. The majority of those damaged cells will be taken out by
the immune system, but every now and again one will get through and that
genetic damage will lead to the production of mutant cells.

Question 10

How can tumours grow?

Answer 10

Those cells may
grow to form a tumour, as its size increases so it will induce blood vessels to
grow into it and support it

Question 11

How do malignant tumours spread?

Answer 11

If tumour is malignant, one that’s going to spread
throughout the body, it will start locally invading the tissues around the
tumour, and then cells will start to spread more widely often through the
lymphatics and then the blood to be transported throughout the body.

Question 12

What do lymph nodes do?

Answer 12

Note
lymphatic system passes through lymph nodes which are major sites of
immune activity and consequently a number of cells will be picked up and
stopped at those points. Eventually the cancer cells will invade the lymph
nodes and on into other tissues of the body a process called metastasis.

Question 13

What are carcinogenics?

Answer 13

Things that trigger the development of cancers

Question 14

What are examples of carcinogenics?

Answer 14

Chemicals, ionising radiation and ultraviolet radiation, viruses, and family history.

Question 15

What are the hallmarks of cancer?

Answer 15

Sustaining proliferative signalling, evading growth suppressors, activating invasion and metastasis, enabling replicative immortality, inducing angiogenesis, resisting cell death.

Question 16

How do cancer cells sustain proliferative signalling?

Answer 16

normal tissues tightly
regulate the growth and division of cells to maintain the cell number and
normal structure and function of tissues. But in cancer cells they are
deregulated which gives the cells the ability to enhance and sustain cellular
proliferation, they are out of control, the normal controls that is.

Question 17

What do growth factors do?

Answer 17

Growth
factors control progression through the cell cycle and growth. In normal cells
and tissues the production of growth factors is strictly limited by spatial
interactions and over time. Cancer cells can overcome these limitations in a
number of ways.

Question 18

How can cancer cells overcome growth factor limitations?

Answer 18

They can themselves produce growth factor ligands, similar chemicals which
stimulate growth inn the same way as the naturally occurring growth factors;

they can stimulate adjacent normal cells to produce growth factors, these
normal cells close to the tumour are identified as the tumour associated
stroma and are under the influence of the tumour cells.

They can also increase
the production of receptor proteins for the growth factors and so make
themselves, the tumour cells hyper responsive to any growth factor that is in
their vicinity.

And perhaps the most sneaky trick is to avoid the regulator
points completely and stimulate the reactions further down the chain.

Question 19

How do cancer cells evade growth suppressors?

Answer 19

Avoid the checkpoint by bypassing it.

Inactivate the tumour suppressor gene: . The tumour suppressor genes function
as regulatory points managing the decision to activate self destruction through
senescence or apoptosis linked to the RB (retinoblastoma) and TP53 proteins.

Question 20

What is apoptosis?

Answer 20

Apoptosis or programmed cell death is a natural barrier to cancer
development. It is a process where the internal structure of the cell break
down in an orderly manner, the cell shrinks and is finally removed by
macrophages phagocytosing the remnants. Unlike necrosis, apoptosis does not
induce an acute inflammatory response.

Question 21

What triggers apoptosis?

Answer 21

. Apoptosis is normally triggered by
physiological stress which in the case of cancerous cells oncogene activity
and increased DNA damage associated with hyperproliferation.

Question 22

What is autophagy?

Answer 22

Autophagy is a process of intra-cellular tidying, damaged cellular organelles,
defective proteins and other materials in the cells that could cause damage are
collected and fused with a lysosome containing enzymes that break down
these defective bits for reuse within cellular metabolism.

Question 23

How do cancer cells enable replicative immortality?

Answer 23

The successful cancer cell will continue dividing in an uncontrolled manner
unlike normal cells which will be limited by senescence which is an
irreversible transition into a functioning but non proliferative state; or crisis
which leads to cell death. Cancer cells have the ability to avoid these and
become immortal.

Question 24

What is angiogenesis?

Answer 24

Tumours are very active tissues and need a ready supply of nutrients and
oxygen alongside the removal of waste products and CO2, angiogenesis is the
process by which the blood supply to the tumour is developed, it involves the
development of new endothelial cells assembling them into tubes creating
new blood vessels. In the adult vasculature this process is switched off other
than in wound healing and in the female reproductive cycling

Question 25

How does cancer progress into adjacent tissues?

Answer 25

In normal cells attachment to adjacent cells and the extracellular matrix
inhibits further cell division. This is mediated by a cell to cell adhesion
molecule E-cadherin. Cancer cells lose this molecule or downregulate it
allowing further growth and cell division of the cancer and its progress into
adjacent tissues.