Is Cancer a preventable Disease?

Yes, to a large extent. About 50% cancers are Tobacco related e.g. Lung Cancer, Cancer of Mouth, Cancer of the Voice box, Cancer of the Food pipe, etc.
Avoiding intake of Tobacco can prevent these cancers. Also, avoid alcohol.
Hepatitis B vaccination reduces risk of this infection and subsequent liver cancer.
Good hygiene and having reduced number of sexual partners reduces risk of cervix cancer.