Yes you can use channel cache in a conditional node. Below is a sample custom script
var value = (channelCache.getValue('TEST') !== null ? channelCache.getValue('TEST') : new java.lang.String('')); return value.equalsIgnoreCase('test');
var value = (channelCache.getValue('TEST') !== null ? channelCache.getValue('TEST') : new java.lang.String(''));
return value.equalsIgnoreCase('test');