Understanding Cancer

What is Cancer?

Cancer is a disease which occurs when changes in a group of normal cells within the body lead to an uncontrolled, abnormal growth forming a lump called a tumour; this is true of all cancers except leukaemia (cancer of the blood). If left untreated, tumours can grow and spread into the surrounding normal tissue, or to other parts of the body via the bloodstream and lymphatic systems, and can affect the digestive, nervous and circulatory systems or release hormones that may affect body function.

Types of Tumours

Cancer tumours can be divided into three groups: benign, malignant or precancerous

  • Benign Tumours

    Benign tumours are not cancerous and rarely threaten life. They tend to grow quite slowly, do not spread to other parts of the body and are usually made up of cells quite similar to normal or healthy cells. They will only cause a problem if they grow very large, becoming uncomfortable or press on other organs - for example a brain tumour inside the skull.

  • Malignant Tumours

    Malignant tumours are faster growing than benign tumours and have the ability to spread and destroy neighbouring tissue. Cells of malignant tumours can break off from the main (primary) tumour and spread to other parts of the body through a process known as metastasis. Upon invading healthy tissue at the new site they continue to divide and grow. These secondary sites are known as metastases and the condition is referred to as metastatic cancer.

  • Precancerous (or premalignant) Tumours

    Precancerous (or premalignant) describes the condition involving abnormal cells which may (or is likely to) develop into cancer.

Types of Cancers

Cancer can be classified according to the type of cell they start from. There are five main types:

  • Carcinoma

    A cancer that arises from the epithelial cells (the lining of cells that helps protect or enclose organs). Carcinomas may invade the surrounding tissues and organs and metastasise to the lymph nodes and other areas of the body. The most common forms of cancer in this group are breast, prostate, lung and colon cancer

  • Sarcoma

    A type of malignant tumour of the bone or soft tissue (fat, muscle, blood vessels, nerves and other connective tissues that support and surround organs). The most common forms of sarcoma are leiomyosarcoma, liposarcoma and osteosarcoma

  • Lymphoma and Myeloma

    Lymphoma and Myeloma are cancers that begin in the cells of the immune system. Lymphoma is a cancer of the lymphatic system, which runs all through the body, and can therefore occur anywhere. Myeloma (or multiple myeloma) starts in the plasma cells, a type of white blood cell that produces antibodies to help fight infection. This cancer can affect the cell's ability to produce antibodies effectively

  • Leukaemia

    Leukaemia is a cancer of the white blood cells and bone marrow, the tissue that forms blood cells. There are several subtypes; common are lymphocytic leukaemia and chronic lymphocytic leukaemia

  • Brain and Spinal cord Cancers

    These are known as central nervous system cancers. Some are benign while others can grow and spread.