The definition of sub-health was studied from the angle of tumor dormancy again. We believe it is necessary to further supplement the present definition, diagnosis criteria, and assessment means. The definition of sub-disease and the division of a disease into four development stages (health --> sub-health --> sub-disease --> disease) were also brought up. Furthermore, we believe that application of regulating sub-health as preventive and therapeutic strategies for tumor is an anti-cancer method with Chinese features, which enriches the modern theories of tumor prevention and therapy.