custom data in url

You can use the details here in this answer to solve your problem :

Pretty URL with add_query_var

Something along the lines of

add_rewrite_endpoint('item', array(EP_PAGES)); 

resulting in a rewrite rule that would let you use /prof/vac/item/1234 which you would then check in the vac pages template for a query variable ‘item’ and pull its value ( in this case 1234 )

Of course one must then avoid having a page with the slug ‘item’ else bad things will happen.