Reiki in general has the Ability to treat All conditions - either in a Major way or a Minor way.  Reiki is an Intelligent, Subtle energy that goes to where it is needed. It will Help Kickstart Natural Healing Processes within the Recipient's body if this is for the Recipient's Highest Good.

From a Spiritual Perspective, we have illness in the body as the body is communicating that there is an imbalance somewhere.  Once the imbalance(s) have been corrected, Healing will take place.