Schreiber has been a leader in a major revision of scientists' understanding of how the immune system interacts with cancer. His work has helped reveal that the immune system is not only capable of destroying cancers, but also can drive them into a dormant state or, in some cases, enhance their malignance.

The research has had far-reaching effects on clinical efforts to enlist the immune system's help in the battle against cancer. Schreiber's insight that the immune system can drive cancers into dormancy, for example, has suggested that immune therapy may one day allow cancer to become a chronic but controllable condition.