Hi Andy,
the distributed cache is not part of SharePoint itself.
If you are installing it on the same box as SharePoint, then you need to gracefully stop the distributed cache on the SharePoint machine you plan to patch to ensure that it the cached content is sent to the other machines in the cache cluster. After the distributed cache service has been shut down gracefully you can patch the SharePoint machine, do reboots if required and so on.
To gracefully shut down the distributed cache on a specific machine please use this command:
Stop-CacheHost -HostName … -CachePort … -Graceful
See here for details:
https://technet.microsoft.com/en-us/library/jj219613.aspx#graceful
Cheers,
Stefan