INDEED, YOU MUST NOT FORMAT IT!!!
ISOBuster should be able to read it even though Windows Explorer can't read it. It will probably ask if you would like to create a managed image of the disc, just do that and work on the image created.
Edit: If that CD-RW is written using the UDF filesystem, I think ISOBuster has to be registered as Professional to help you out in all aspects of the filesystem, more information thereof: http://www.isobuster.com/license-models.php