This exact form of the surname is very rare with Jewish families.
Consolidated Jewish Surname Index (CJSI), www.avotaynu.com/csi/csi-home.html
, a database of 370,000 different Jewish surnames from many sources, lists only 3 sources for this surname, fron Russia and Latvia.
An address of a researcher for KADAN from Russia can be found at www.jewishgen.org/jgff/jgffweb.htm
A record for one Jew named Judel Kadan, who avoided paying tax in Vilnius, Latvia, can be found at www.jewishgen.org/databases/Latvia/