to Cable Forum
Unfortunately combined ADSL modem with routers do not operate on cable systems. There is no provision on such combined kit to output the router only function to a WAN connection that would attach to a cable modem or Set Top Box. ADSL and cable are different technologies so ADSL modems are incompatible with cable.
best suggestion, if you opt for cable is to ebay your existing kit, and buy a new router. If you then ever return to ADSL the router standalone could be used on ADSL simply by adding an ADSL modem.