Anything is possible with linux.
Now type "df -h" at the command line. Look at the last column, see if you have anything mounted at /home
If not you should next time. One of the great parts about linux is a multi-partition setup allows you to replace your entire os without loosing your home directory.
If you don't have a dedicated home partition, the easy solution would be to back it up to disk before formatting. If it is extremely large, and you do indeed only have one partition, it might be possible to use gparted to shrink that partition and make a home partition in advance. However this would kinda be a pain, and probably take forever on a large hard drive.