Hi Michelle,
Leukoplakia literally means 'white patch' and can be caused by a number of factors from smoking to ill-fitting dentures. More generally, it is thought to be the result of some sort of chronic irritation. Sometimes removing the source of irritation will result in the disappearance of leukoplakia, but in some percentage of cases, it can be a precursor to oral cancer.

From what I've read, leukoplakia that does not go away with treatment within a few weeks should be followed closely. Typical treatment for removing it can include removal by surgery, burning it off with a laser or freezing it off with a cryoprobe.

The Mayo Clinic website has a pretty good discussion of leukoplakia and its treatment at:
http://www.mayoclinic.com/invoke.cfm?objectid=FA822BBB-FC4E-4F9F-96496DCD1FC7B8CA&dsection=1

In any case, it sounds like your co-worker's husband is getting the appropriate surveillance by the ENT. I don't know what the state of medical care is in Steven's Point but you may want to suggest a second opinion at a larger facility with more experience in treating oral cavity disorders. Hope this helps. - Sheldon