What is cancer and how does it develop?

Cancer is a disease where the cells grow abnormally, out of control, in the wrong place.
Our bodies are made from billions of cells, like bricks make a house. The cells in our bodies that make up the heart, lungs, kidneys, muscles and skin are all quite different.
When cells are damaged, they can start growing in a way that is not normal and the uncontrolled cells will form a lump called a tumour.

Cancer can affect men, women and children, young and old, rich and poor.
You cannot catch cancer from someone else nor give it to others. With new methods of treatment, many people recover from cancer now.
You can have cancer anywhere in the body, including the bones and the skin.

How do I know that I have cancer?

If you have had one of the following problems for over 3 weeks and it is not getting better with ordinary treatment, you should visit a doctor or clinic.

How does cancer develop?

Cells are constantly renewing themselves. Each day cells die and are then replaced by new cells; this is how we stay healthy. But sometimes during this renewing, a healthy cell changes into a cancer cell and starts growing out of control.

Tumour growth

When the tumour grows, some of the cancer cells damage normal cells and can then move into different parts of the body. The cells that travel into other parts of the body are called metastases.
These cancer cells travel through the blood or the lymphatic system to distant parts of the body where they form new tumours. In this way, breast cancer for example can spread to glands under the arm, the lung or the brain.

The doctor will speak of “stages”. This explains how much cancer is in a person’s body and where it is located.

Stage 1 and 2 means that the cancer is in an early phase, still small and responding well to treatment. Stage 3 and 4 shows that the cancer cells have travelled to nearby organs or have spread through the blood vessels and is more difficult to treat.

Stages of Breast Cancer

How does the doctor find cancer?

First the doctor will listen to your story and do a physical examination. Then he can use a number of ways to find out if it is cancer or not.


 A small piece of the tumor is cut out and looked at under a microscope to determine the type of cancer.


Endoscopy is a medical procedure where a doctor puts a tube-like instrument into the body to look inside. There are many types of endoscopy, each of which is designed for looking at a certain part of the body e.g. gastroscopy for the stomach and cystoscopy for the bladder.

CT scan or MRI scan

The machine takes many pictures (x-rays) of the body taken from different angles. These pictures are combined to give a detailed picture of internal organs. Doctors are then able to look for tumours. The CT and MRI scans are painless.


Is a special type of low dose x-ray used to detect breast cancer. The breast is compressed (squeezed by a machine) during the procedure and so it may be a bit uncomfortable.


Sometimes cancer cells give off substances that can be detected in the blood. This tells the doctor that there is cancer somewhere in the body. They are called blood markers.

Why do I have cancer?

It is difficult to know why certain people get cancer, and others don’t. Doctors use the term risk factors to describe things that damage the cells so they can grow into tumours.

Risk factors include:

  • Smoking cigarettes or using tobacco products like snuff, pipe or chewing tobacco.
  • Having been sunburned often
  • Some viruses: HIV, HPV and Hepatitis B virus
  • Unhealthy lifestyle: being overweight, limited physical exercise, too much alcohol, too many sugars and too much red meat, not enough vegetables and fruit
  • Inheritance: a family history of cancer – some of your close relatives (father, mother, brothers or sisters) have had cancer: breast, bowel, melanoma and ovarian cancers).
  • Pollution and toxins in the environment (dirty air and water, smoke and chemicals that we breathe in).

Why is it important to go to a doctor when you notice symptoms?

Many people recover from cancer every year, completely or temporarily.
Doing so is easier when cancer is diagnosed at an early stage as treatment is often simpler and more likely to be effective. So finding cancer early can make a real difference.
Sometimes, people put off seeing their doctor because they’re worried about what the doctor might find, but it is important to remember that advances in the way cancer is diagnosed and treated have led to real improvements over the years. The earlier, the better!

(see “CAUTION” above)