Severe Weight Loss After Surgery

My husband was diagnosed with bladder cancer in December 2010 and attempted to take chemo prior to surgery to remove his bladder (muscle invasive) but he could not tolerate the chemo or radiation.  His surgery was May 16th and in the hospital for 11 days because he had a reaction to the drug Reglan(?)  Prior to surgery he was in "good health" working out 3 times a week and weight was at 175.  His weight when dismissed was 169 but expected this to drop due to fluid retintion as well as removal of the bladder, prostrate and one lymph node that showed cancer.  He is now going into 6 weeks and his weight continued to drop and now at 152/153 and he is so weak cannot walk well.  The surgeon's last check up was on the 21st of June and seemed to think that due to the extensive surgery it was, his age (81) it would be expected to have a longer recovery.  He has now turned us back to the oncologist for a CAT scan and blood work to begin monitoring any future cancers and to discuss possible appitite enhancer altho he is eating and doing the mid-meal "Boost" high protein type drinks.  The home health care nurse has expressed concerns and arranged to move up his appt with the oncologist to this week.  We will also now be monitored by the local urologist and have a follow up with him on the 7th of July.  Has anyone had experience with this severe a drop in weight, got back up to what would be "normal" and able to function.  He is doing well with the stoma and external pouch routine (well, I am since he is to weak to deal with it himself) and for that we are grateful.  Thank you for any information or comments.