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Cancer - a general overviewThis factsheet is for people who have cancer, or would like information about it. Cancer is caused by the cells of the body changing so that they grow in an uncontrolled way. It's estimated that one in three of us will get cancer at some point in our lives. This factsheet is to help you understand more about what cancer is and how it is diagnosed and treated Cancer - a general overview animation
What is cancer?Your body is made up of cells. There are many different types of cells that do various jobs and form the organs (such as the heart, stomach and liver) and tissues (such as bone, muscle and blood vessels) in your body. These cells reproduce by dividing, so one cell will split into two cells, then those two cells will split again and so on. This is how your body grows and repairs itself. Normally cells grow and reproduce in a controlled way - they stop growing when the body tells them to. The control centre for the cells of your body is its nucleus. The nucleus contains genes, which are bits of code that tell the cell what to do. Sometimes, this code goes wrong and the cell keeps on growing and growing, forming a lump called a tumour. There are two main types of tumour: benign tumours and malignant tumours. Malignant tumour is another term for cancer. Benign tumoursTumours that don't invade (grow into) other tissues or spread to other parts of the body are known as benign. Benign tumours are not cancerous. They normally grow slowly and are made up of cells that are very similar to normal cells. As a benign tumour gets bigger, it takes up more space and presses on the organs and tissues next to it. Malignant tumoursTumours that invade surrounding tissue and spread to other parts of the body are known as malignant. Malignant tumours are cancerous. They are usually more "aggressive" and grow faster than benign tumours. They can spread through the bloodstream and lymphatic system to other parts of the body to form secondary tumours. This spreading through the body is called metastasis (pronounced "met-as-tah-sis"). Types of cancerThere are several different types of cancer. They are named by the types of cells they are formed from. CarcinomaThis type of cancer starts off in the cells that line the organs and tissues. These are called epithelial cells. Lung cancer, prostate cancer, breast cancer and stomach cancer are all types of carcinomas. They are the most common type of cancer - up to 85 percent of cancers are carcinomas. There are different types of carcinoma, depending on the type of epithelial cell they come from. There are four main types of epithelial cells:
So, for example, a cancer that starts in squamous epithelial cells is called a squamous cell carcinoma. SarcomaThis type of cancer starts off in the cells of the supportive tissues of the body, such as in bone, muscle, cartilage, blood vessels and fatty tissue. Sarcomas are much less common that carcinomas and make up around six percent of all cancers. There are two main types of sarcomas:
Leukaemia and lymphomaThese cancers start off in white blood cells (which are part of the body's defence system) in the bone marrow and lymphatic system. They make up around five percent of all cancers. OthersOther, rarer, forms of cancer (eg brain tumours) make up the remaining four percent of cancers. Cancers that form from different cell types behave differently - for example, certain cell types are more likely to grow fast and spread than other types. Cancer is not infectious and can't be caught from other people. What causes cancer?One of the biggest risk factors for cancer is increasing age - more than seven in 10 cancers are in people who are over 60. Other risk factors include:
Most cancers are probably caused by a combination of these risk factors. Diagnosing cancerThere are several tests available to diagnose cancer. Normally, you will start by seeing your GP, who may refer you to a specialist for further tests. These tests may include blood tests, X-rays, MRI scans, CT scans, ultrasound scans, cystoscopy and endoscopy - depending on your symptoms and the part of your body that's involved. You will probably need to have a sample (a biopsy) of the abnormal area taken. This will be sent to a laboratory and analysed, to find out if there are cancer cells, and if so what type they are. Primary and secondary cancerThe place where the cancer starts is called the "primary" cancer. Cancer cells can move through your blood vessels and lymphatic system and spread (metastasise) to other parts of your body to form more tumours, called "secondary" tumours. Grading and stagingGrading and staging systems are used to classify cancers to work out how your cancer is likely to behave, and what the best treatment options will be. If you have a scan (eg a CT scan or an MRI scan) and biopsy, these will be used to provide the information for the grade and stage of your cancer. Grades of cancerThe "grade" of cancer means what the cells look like under a microscope. The lower the grade, the more like a normal cell the cancer cell looks. Normal cells are specialised for the different jobs they do in your body. This is called differentiation. Cancer cells tend to be unspecialised, or poorly differentiated. Cancer can be divided into different grades:
A low grade cancer usually grows more slowly and is less likely to spread to other parts of the body. A high grade cancer usually grows more quickly and is more likely to spread to other parts of your body. An example of a grading system is the Gleason grading system, which is used to grade prostate cancer. Staging"Staging" is a system that is used to describe how advanced the cancer is. It describes how large the primary tumour is, and whether it has invaded nearby tissues and spread to other parts of the body. There are several different staging systems, depending on the type of cancer. These include:
TreatmentThe treatment will depend on the specific type of cancer, plus the grade and stage. The most common treatments are chemotherapy, radiotherapy and having surgery to remove the cancer. Other, newer treatments include hormone therapy, gene therapy, immunotherapy and bone marrow transplant. Treatment may be given to:
For more detailed information on specific treatments for a specific type of cancer, please see the separate BUPA health factsheet on the type of cancer you would like to find out about. Help and supportBeing diagnosed with cancer can be distressing for you and your family. An important part of cancer treatment is having support to deal with the emotional aspects as well as the physical symptoms. Specialist cancer doctors and nurses are experts in providing the support you need, and may also visit you at home. If you have more advanced cancer, further support is available to you in hospices or at home, and this is called palliative care. Further information
Sources
Related BUPA factsheetsPublished by BUPA's health information team, healthinfo@bupa.com, May 2007.
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