The organs and tissues of the body are made up of tiny building blocks called cells. Cancer is a disease of these cells. Cells in different parts of the body may look and work differently but most reproduce themselves in the same way. Cells are constantly becoming old and dying, and new cells are produced to replace them. Normally, cells divide in an orderly and controlled manner. If for some reason the process gets out of control, the cells carry on dividing, developing into a lump which is called a tumor.

There are two types of tumors benign and malignant. Benign tumors are not cancer. They often can be removed and, in most cases, they do not come back. Cells in benign tumors do not spread to other parts of the body. As a result, benign tumors are usually not considered life threatening.

Malignant tumors are cancer. Cells in malignant tumors are abnormal and divide without control or order. These cancer cells can invade and destroy the tissue around them. They can also break away from the original tumor, and enter the bloodstream or lymphatic system (the tissues and organs that produce and store cells that fight infection and disease). This process, called metastasis, is how cancer spreads from the original (primary) tumor to form new (secondary) tumors in other parts of the body.

In many cases, the exact cause of the cancer is unknown. However, we do know that there are some things that can increase the risk of different types of cancer.

Family and personal medical history can affect your risk. Exposure to carcinogens in the environment, such as chemicals or radiation, can increase your risk. A carcinogen is a substance that can cause cancer.
In addition, cancer can be more likely to develop when the immune system isn't functioning properly.

How is treated?

There are six main types of treatment for cancer:
Some types of cancer grow very slowly and may cause no problems for many years. In this situation you may not need to have any treatment for some time, but your doctor will monitor you closely so that if the cancer does start to grow you can be given treatment at that time.

Surgery: An operation is done to remove the tumor. Surgery is often used if the cancer is only in one area of the body and has not spread. It may be used to remove lymph nodes if these are also affected by the cancer.

The radiotherapy is the use of high energy x-rays to destroy cancer cells, but cause as little harm as possible to normal cells. The radiotherapy is aimed at the affected area of the body and is very carefully planned. It can cause side effects and the most common is tiredness.

Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. There are more than 50 different chemotherapy drugs. Some are given as tablets or capsules but most are given by drip (infusion) into a vein. The drugs go into the bloodstream and travel throughout the body to treat the cancer cells wherever they are.

Hormonal therapies work by altering the levels of particular hormones in the body. Some cancers depend on certain hormones in order to divide and grow. By altering the level of hormones in the body, or blocking the hormones from attaching to the cancer cells the cancer can be controlled.

Biological therapies use substances that occur naturally in the body to destroy cancer cells. There are several types of biological therapy, including: monoclonal antibodies, cancer growth inhibitors, vaccines and gene therapy.