Subject: How can you tell if a tumor is cancerous or benign -if it will metastasize?

Both cancerous and benign tumors consist of cells that are dividing at
an uncontrolled rate - right? Then how can you tell if it's cancerous
or not? I understand that it is considered cancerous if it metasticizes,
but how can a doctor tell if it is going to metastasize? Is there some-
thing different about the cells of benign tumors that a doctor can see
that they won't metastasize? This has been bugging me for ages!

Re: How can you tell if a tumor is cancerous or benign -if it will metastasize?