What is cancer?

Every human body consists of billions of small cells. These form different tissues and organs such as skin cells, bone cells, blood cells, liver cells and many other kinds of cells. The cells have a variety of functions, the skin protects the body, the blood transports sustenance and oxygen, the muscles enable movements and so on.

The body’s cells have varying life spans. Old cells die and are replaced through cell division with similar cells which then continue to function in the same manner. The normal cell division of tissues is governed by the cell’s thousands of genes which contain genetic materials that are passed on from one generation of cells to the next. The cell division of a normal, healthy cell is therefore a strictly regulated process. Millions of cell divisions take place in our bodies every hour and in many cases defective cells are formed, which are then destroyed by the immune system.

Cancer is a consequence of a disturbance in the balance of normal cell division, where the cell division continues even after it should have stopped. The cell becomes genetically modified by a variety of causes and eventually the cancer cells form small lumps, tumours that grow and spread. This process is long and it can take decades for us to discover the cancer.

Just as there are several different types of cells and body tissues, there are also different forms of malignant conditions that are called cancer, sarcoma, lymphoma and leukaemia, depending on where they have developed, such as lung cancer, breast cancer, renal cancer. Malignant tumours in the connective tissues, for example in bones, muscles and fat tissues, are called sarcomas. Malignant tumours in lymph nodes are called lymphomas and malignant changes in the different cells of the bone marrow give rise to leukaemia.

For further reading see these links:

http://www.cancer.gov/cancertopics/cancerlibrary/what-is-cancer
http://www.cancerfonden.se/sv/cancer/Vad-ar-cancer/
http://www-genvagar.slu.se/evolution/gymnasie/cancer3.htm
http://www.novartis.se/behandlingomraden/cancer/om_cancer.shtml