Cancer is a sickness that destroys cells. Cells become damaged and abnormal in the individual who has cancer. When cells become unhealthy they are supposed to die and new healthy ones are supposed to develop. Abnormal cells do not die when a person has this sickness instead the abnormal cells reproduce. The abnormal cells eventually form a tumor. Specialists are doctors who have completed eight years of training and three to seven years of internship in a specific area of medicine. After the internship the doctor can take an exam to become a certified specialist.