The body is made up of cells which are continually multiplying and working to replace those which have become damaged or worn out. This is a constant process which keeps the body working normally and ‘repairs’ it when, for example, you suffer an injury or have an operation. Cells in different parts of the body have different life cycles and multiply at different rates, but what is common to them all is that they contain signals which tell them how to behave and when to multiply.
Cancer happens when a single normal cell starts behaving abnormally. The cell begins to divide and grow uncontrollably because the signals which tell it how to behave are not working properly. The same happens to the cells it produces but because these cells are so minute, the effect of their growth can remain undetected in the body at this stage. The place in the body where this abnormal growth begins is known as the primary site of the cancer and the resulting tumour as the primary tumour. Although there are many, many different cancers, they are generally described in terms of their site of origin, so that lung cancer refers to a tumour which originated in the lung.
The next stage in the development of the cancer is for the cells to invade the tissue which immediately surrounds them. Next they can circulate to other parts of the body via the bloodstream or lymph vessels, which both reach all parts of the body and therefore provide an easy means of ‘transport’ for the cancer cells. The cancer cells arrive at a new site in the body (which can be quite distant from the primary tumour) and again invade the surrounding tissue. The resulting tumour is known as a secondary tumour or metastasis, and is directly related to the primary tumour. For example, bowel cancer tends to spread via the vascular system to the liver. The secondary tumour in the liver is not referred to as cancer of the liver, but as a ‘secondary cancer of the bowel’. The distinction is important in understanding your cancer: in this example, the spread does not mean that you are suffering from cancer of the bowel and cancer of the liver. It is the ability of the cancer cells to travel around the body and invade other sites which makes cancer such a difficult disease to treat effectively. If it were simply a question of treating a single abnormal ‘lump’, then this could in many cases be removed surgically and the problem eliminated.
Different cancers spread and invade other sites in the body at varying rates, but the sites where they metastasize (form secondary cancers) tend to follow a pattern. For example, testicular cancer spreads first to the lymph nodes in the abdomen, sometimes to the lungs and in some cases to the liver or brain.
Although cancers are generally described by their site of origin, you may also encounter other terms used to describe your cancer, according to the type of tissue where it originated. The most common of these are:
Carcinoma
Carcinomas account for a large proportion of all cancers. A carcinoma is a cancer which originates in the epithelial cells of the body. This is a layer of lining or covering cells which is found in the lungs, the stomach and digestive system and also on the surface of the skin and in glands throughout the body.
Sarcomas are less common. A sarcoma is a cancer which forms in the tissues which connect the parts of the body together – the bones, muscle, cartilage, tendon and so on.
Lymphoma
Lymphoma refers to the cancers which originate in the lymph nodes and lymphatic tissue, although some lymphomas can start in the bone marrow.
Leukaemia
Leukaemias are cancers of blood cells. They originate in the bone marrow and affect the white cells in the blood and, in turn, also the red cells. The white cells are important because they affect your body’s ability to fight infection and the red cells carry oxygen around the body.
A relatively small number of different cancers account for a high proportion of cases newly registered each year, the more common being the lung, colorectal, prostate and bladder cancers. These account for around half of the total cases and, as with many cancers, are most common in older men. The main exceptions to this for men are cancer of the testis whose incidence peaks before the age of 40, and the leukaemias which have two peaks, one before the age of 20 and the other around the age of 70.
*6\118\2*
Leave a Reply
You must be logged in to post a comment.