The only way to know is after surgery. A biopsy following a colonoscopy can tell if there is cancer present, but the only way to know for sure if the lymph nodes have been invaded is after surgery (which is only performed if the tumor has gone into the colon wall–otherwise, there is no way the lymph nodes are invaded, since they are on the outside of the colon). the part that is removed will be inspected, and they will check then to see how many lymph nodes (if any) have been invaded.
go to your doctor!