Why is cancer so aggressive? understanding its behaviour.
What is cancer?
Cancer is a disease in which cells grow uncontrollably and has the ability to spread to other parts of the body. Cancers can start growing in any part of the body and metastasize (spread) from there. There are more than 100 types of cancer and they are usually named depending on where they were originated. For instance:
Lymphoma is originated in the cells of the lymphatic system.
Leukaemia is one type of cancer that develops in the bone marrow, where white blood cells are formed and affect the cells in the blood.
Myeloma develops in the plasma cells.
Carcinomas start in the cells that are between the skin and body cavities.
Sarcomas grow in tissues such as muscle, bone and fatty tissue.
How does cancer start…
Normally, the cells in our body grow and multiply, through a process called cell division, to form new cells. Later, once the cells grow old or become damaged, they die, and new cells take their place and this process is regulated by signals the body sends to those cells.
Sometimes this regulation process breaks down, and abnormal or damaged cells which should be killed and replaced, are able to grow and multiply. These cells may form tumours, which are lumps of tissue. Tumours can be cancerous or non-cancerous (benign).
The difference is that benign tumours do not spread to other parts of the body and when they are removed they usually don’t grow back. However, cancerous tumours, also known as malignant tumours, sometimes do grow back after been removed and do spread to other parts of the body (metastasis). Benign tumours can sometimes be quite large and can cause serious symptoms or be life-threatening, such as benign tumours in the brain.
Malignant tumours can either be solid or liquid, this last one would be for example the cancers of the blood like leukaemia.
Why do cancer cells grow abnormally…
Cancer cells, as mentioned previously, have the ability to avoid the signals telling them not to grow and also do not need any signal to continue growing. Normal cells only grow and stop growing when they receive such signals.
Cancer cells invade nearby tissues and spread to other areas of the body. They also are able to tell blood vessels to grow toward tumours, in order to receive oxygen and nutrients and remove waste products from tumours.
Something that is being studied a lot at the moment is how they have acquired the ability to hide from the immune system, which is responsible for eliminating damaged or abnormal cells.
Not only it’s able to avoid the immune system but also trick it into helping cancer cells stay alive and grow. For instance, some cancer cells convince immune cells to protect the tumour instead of attacking it.
Cancer cells accumulate multiple mutations in their chromosomes ( duplications and deletions of chromosome parts) and double the abnormal number of chromosomes.
Some cancer cells make energy from nutrients in a different way than most normal cells and this contributes to the aggressive behaviour cancer cells have.
