For those who are not familiar with the Immigrant Police files in Belgium, the Belgian gov't essentially kept files on every foreigner living within its borders, from about 1840 to the 1990s. These file vary in size, but I've found files over 80 pages in length (some are just a page or two, most are at least 10). If the person lived in Belgium after WWI there is almost certainly a photograph. Files list where the person came from, the names of their parents and where they were from, and more...
Last year FamilySearch indexed the files (http://goo.gl/sXUV7)
that exist in Antwerp (so just people who lived in Antwerp, not all over Belgium which are centralized in the State Archives in Brussels).
I decided to try searching by location, and the following 7 people show up as being born in Kanczuga:
Mala Frieder, b. 1901
Abraham Silbermann, b. 1904
Naftali Schiffman, b. 1909
Isaak Schupper, b. 1894
Benzion Frommer, b. 1903
Baruch Goldman, b. 1883
Meilech Horowitz, b. 1897 (he's listed twice, as Meilech Horiwitz and Meilich Horowitz, but they list the same file #)
That doesn't tell the whole story, however, as it seems that while it will search for variations of names, it doesn't do that for locations (or at least not well). I looked up the original hand-written index for Mala Frieder and the next line shows a Frieda Frieder also born in Kanczuga (but spelled Kaunczoga). Thus, there are probably more people from Kanczuga in the files.
In addition, some people will only show up in the central file in Brussels. My gg-grandfather Isaac Trauring is in the Brussels files but not listed in the Antwerp files, even though he lived in what is now Antwerp. It is possible that he lived in a different town that only later became part of Antwerp (like Bercham) and thus doesn't show up in these older Antwerp files (which wouldn't include Berchem). I'd have to take a closer look to figure that out, however. There is no way to search the Brussels files by location as they are only indexed by name (and by indexed, I mean on card files in drawers).
Anyways, if one of the above 7 people is a relative of yours, you can have someone go to the Felix Archives in Antwerp and make a copy of the files to a USB drive (the files are on microfilm and they have microfilm scanners) for free. If you don't know anyone in Antwerp, there are volunteers online who can help. For complete coverage of these files, it's worth contacting the State Archives in Brussels (for instances like my gg-grandfather). If you know your family lived in Belgium at some point and need help accessing these files, let me know. This is actually the topic of my lecture at the IAJGS conference in DC next month.