Is there a connection between stomach cancer and colorectal cancer?

Maybe: But only in the rare case of non-hereditary polyposis colorectal cancer is there an association. It is an extremely rare inherited condition(nhpcc).

No?: In practical terms there is not. Gastric or "stomach cancer" is more common in japan, iceland, chile and costa rica were "volcanic" soil is common and diet is rich in fruit and vegetables. Colon cancer is common in societies ( like usa) were diet is poor in fiber & diet relies on more refined foods (from canned or processed food). I guess one can metastasize into the other. Exceptions do exist.