What are the causes of cancer and what causes it to spread?

Mutation: Cancer is an abnormal proliferation of cells. There are mutations in the dna that lead to the uncontrolled growth of the cells.There are certain environmental factors like tobacco smoke or radiation that are clear mutagens.The cells grow rapidly and lose their contact inhibition-thus their local spread and invasion. Cancers can also spread through the blood and set up at distant sites (metastases).