Everything Life Sciences Grade 10

FACT

WATCHsome
videos to learn
more about how
normal cells turn
cancerous.
See video:
SHORTCODEat
http://www.everythingscience.co.za
See video:
SHORTCODEat
http://www.everythingscience.co.za
See video:
SHORTCODEat
http://www.everythingscience.co.za
See video:
SHORTCODEat
http://www.everythingscience.co.za

FACT
There are hundreds
of different types of
cancer. For a
comprehensive list
visit:http:
//en.wikipedia.
org/wiki/List_
of_cancer_types

the body to stop growing and dividing. However cancer cells do not respond to signals

from the body and keep on dividing.

2.Cancer cells grow new blood vessels: as the tumour grows larger, it begins to release

proteins from the cell to attract new blood vessels. Blood vessels draw nutrients away

from healthy cells and therefore starve them while allowing the growth of the tumour.

The new blood vessels also enable cancer cells to enter the bloodstream and spread to

other parts of the body.

3.Cancer cells spread around the body: another feature of cancer cells is that they can

spread around the body (metastasise). Tumours that have the ability to spread to other

parts of the body are calledmalignant. Cancer cells can spread to surrounding tissues

via the bloodstream or via the lymph system.

As previously mentioned, cancer cells aremalignantwhich means they are able to invade

tissues and spread to other parts of the body. Some tumours cannot spread to other tissues

and are calledbenigntumours. Benign tumours are non-cancerous.

Figure 4.4: Benign tumours are unable to metastasise. Malignant tumours are able to metastasise

away from the original tumour site.

Types of cancers

Cancer can affect almost any tissue in the body. A list of some common cancers includes:

• Breast cancer


• Lung cancer


• Oesophageal cancer


• Leukaemia (blood cancer)


• Melanoma (skin cancer)

Cancers often spread to different organs, however it remains the same type of cancer as the

original cancer, it is simply referred to as a metastasis. Therefore melanoma (skin cancer)

that spreads to the liver is not liver cancer, but a melanoma metastasis to the liver.

104 4.4. Cancer