* Cancer is the result of changes in cells that leads to uncontrolled growth and
division.
* Benign tumours are growths of abnormal cells which are contained in one area,
usually within a membrane. They do not invade other parts of the body.
* Malignant tumour cells are cancers. They invade neighbouring tissues and spread
to different parts of the body in the blood where they form secondary tumours.
* Scientists have identified lifestyle risk factors for various types of cancer e.g.
smoking and lung cancer, obesity and cancers of the bowel, liver and kidney. U.V.
radiation from the sun can also cause skin cancer.
* Viral infections can also be a risk factors for certain cancers e.g. HPV and cervical
cancer.
* There are also genetic risk factors for some cancers e.g. having certain faulty
genes has shown an increased likelihood of developing breast and ovarian
cancer.
* If your white blood cells have made a particular antibody in the past they can
remember how to make that particular antibody.
* If you have an illness caused by a particular pathogen your white blood cells
produce the correct antibody and destroy the pathogen.
* If you are infected by exactly the same identical pathogen your white blood cells
will remember how to make the correct antibody, produce it quickly and
destroy the pathogen before it can make you ill.
* If the pathogen is different it will have different antigens on its surface and your
white blood cells will need to make a different antibody to destroy it. – You can
become ill while you are waiting for your white blood cells to make the correct
antibody.
