Each of us has cancer a couple of times per day but our lymphocytes let us not worry about it. All that was wrote above means that cancer is 1) the disease of age and 2) disease of the immune system.
At the moment there's no single treatment which results in a high amount of defeating cancer. Usuaully, the main cancer mass will be removed surgically and then followed up whith chemo-threapy.
You could try wikipedia if you just want a little more information (although I wouldn't recommend citing them from there for say a research paper or something as people can openly edit articles on the site).
