Download Title: What is Cancer?

Title: What is Cancer? - Dr Vani Jain
Description: The podcast covers basic information on the development of cancer
within the body.
Transcript
This podcast will explain what we know about cancer and how we know that the risk
of developing it can be inherited.
Cancer is a term used for diseases in which abnormal cells divide without control.
There are many different types of cancer depending on which tissue or organ they
come from - for example, cancer that begins in the cells of the large bowel is called
colon cancer.
Normally body cells grow and divide in a controlled way to produce more cells as
they are needed to keep the body healthy. When cells become old or damaged, they
are either repaired or they die and are replaced with new cells. This is all occurs in a
controlled way and means that damaged cells don’t divide but, sometimes this
process goes wrong. The cells don’t die like they should and continue to divide and
make cells even though they aren’t needed. If these extra cells form a mass of tissue,
this is can lead to the development of a tumor.
For cells to divide when they shouldn’t the genetic material or DNA of a cell needs to
be damaged or altered in some way. These changes are called mutations and if a cell
accumulates a number of mutations, this mutated cell can develop the ability to
divide without control.
The abnormal cells may also spread to other parts of the body through the blood.
This explains why cancer can spread around the body is a process called metastases.
Cancer is a common illness with about 1 in 3 people in the UK being diagnosed with
cancer during their lives. Most people who get cancer are over 65. It is relatively rare
for young people (those under 50) to get cancer.
These cancers are called sporadic. It is due mutated cells dividing, as explained
earlier but these mutations accumulate in cells over many years and if a particular
cell acquires enough of these, it can become cancerous. This is the case with most
cancers and if you have only one elderly relative with cancer, you’re not usually at a
significantly increased risk of getting the same cancer yourself.
People sometimes think that several cases of cancer in their family may be
connected, and that they have inherited an increased risk of developing cancer. But
only a minority of cancers (5–10%, or less than 1 in every 10 cases) are clearly linked
to an inherited change in the DNA.
DNA is made up of small packets of information called genes. We all inherit a set of
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genes from each of our parents. This includes genes that are important in the control
of cell repair and replication called cancer susceptibility genes and when functioning
normally, they don’t increase the risk of cancer developing.
Inherited or familial cancers are seen when there is a mutation in one of these
genes. This mutated gene can be passed from generation to generation and those
who carry it have an increased risk of developing cancer.
More than one mutation is needed for a cancer to develop. So inheriting a cancer
susceptibility gene doesn’t mean a person has cancer but that they are at an
increased risk of developing certain types of cancer which is higher than the risk to
normal population.
The discovery of inherited, cancer susceptibility genes and an increased
understanding of their role in the disease, has meant that there are now predictive
genetic tests available. These can determine whether an individual with a strong
family history of cancer is at an increased risk of developing the disease.
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