Cancer is a disease that begins inside cells and so being with a person who has cancer is not dangerous and you cannot catch it from them. It is perfectly safe to visit and touch the person who has cancer. There may be times when you should not be in close contact with someone who has cancer but the reason for that would be to protect them from infections that you might pass on and not to protect you from them.
You could take a look in the section called "About cancer" to find out more about cancer and how it develops.
Page updated 23 April 2015