It is possible, but it's NOT easy. To get PHP to read a Word document, you'll first need to be running PHP on a Windows box that has MSOffice installed. Having satisfied that, you'll need PDFlib installed into PHP. If you've managed to satisfy all of those requirements, you can use the COM functions of PHP to open the Word document, and the PDFlib functions to create a document from it. I make this last step sound simple. It isn't.
If you are using this for your own internal purposes, you might look into using GhostScript to to conversions of print captures.