This introductory module describes the purpose of the human immune system, components of the immune system, and innate and adaptive immune responses.

The immune system has a well-established role in human cancers. Recently, many advances in the treatment of cancer have been due, in part, to manipulation of the immune system. This module provides users with a brief overview of the history of cancer immunotherapies and includes a description of a newer hallmark of cancer – evasion from the immune system. The module concludes with an explanation of the theories of immune surveillance, immunoediting and the cancer-immunity cycle.