Regarding cancer, How exactly does a cell mutation spread to other common cell?

Is it some sort of chemical response or is it just that the cancer cell divide replacing normal cell? read here
http://en.wikipedia.org/wiki/metastasis.
the process is called metastasis
cancer cell divide replacing normal cell.
if the malicious cell infest normal cell.. then its because of virus.
Yep, they divide swiftly and take over once they start forming blood vessel of their own. sometimes cells will break bad and get lodged within other places, and that's why people can attain it in a mixture of spots (not the only rationale though).
cancer cells divide hastily and deprive the normal cell of nutrients for the normal cells' further division.
Cancer cell don't spread to normal cell, they invade them. Cancer cells are regular cell that have an accelerate growth, so they start forming a mass, this mass can do pretty much anything: block, compress, destroy. The everyday cells are still nearby, but they have be squashed by the cancer cells.