Yes, very much so!
To check for sure then the easiest way is to remove the piece of trim over drivers side rear wheel arch. Its held in place by 2 torx headed screws, and goes from just below the seatbelt to the floor level. You will need to lower the rear seat to get to one screw and remove the rear seat cushion to get to the other one.
If when you remove that there should be half a dozen or so wires taped into a bundle running around the wheel arch - but if its missing then you have a problem as someone has removed the cable with the changer prior to you getting the car! There should be a minimum of a single black wire - thats the aerial cable and doesn't count!
If the cable is missing then I suggest a call to where you got the car from as the radio could never have worked like that as the speakers are disconnected further down the cable which plugs next to the drivers foot.
The good news is that the replacement cable for this comes with the Bose upgrade and is included in the price, so all isn't lost, in fact if the cable were there then you would replace it anyway.
Its important that when you get a Bose kit that you get one with a CCRT700 and the correct CD changer for it. The CCR800 won't work with the display that's in your car, and the CCR800 and CCRT700 have incompatible CD changers.
Estate wiring is rarer than saloon wiring, but can be modified. You will need to get an estate subwoofer though as they are unique.
There are enough people here to give you advice on making this happen - but a few words with where the car came from are required in my view if that cable is missing.
HTH .......... Rob