If you have set a callback to occur when a cached item is removed, you will be provided with a CacheItemRemovedReason argument. The CacheItemRemovedReason will be Expired if the sliding or absolute expiration time interval passed, Removed if the object was removed programmatically with the Cache.Remove( ) method or by an Cache.Insert( ) method with the same key, DependencyChanged if the object was invalidated because of a dependency, or Underused if it has been removed to free memory.

public enum CacheItemRemovedReason {
   Removed = 1,
   Expired = 2,
   Underused = 3,
   DependencyChanged = 4
}

Hierarchy

System.Object System.ValueType System.Enum(System.IComparable, System.IFormattable, System.IConvertible) CacheItemRemovedReason

Passed To

CacheItemRemovedCallback.{BeginInvoke( ), Invoke( )}