Analysis of National TCM Master ZHOU Zhongying's Clinical Thoughts of the Relation between Healthy Qi and Pathogenic Factors in Treating Cancer

National TCM master Zhou Zhongying is good at treating cancer with rich clinical experience and academic theories. He has come up with the cancerous toxin theory in guiding the clinical work. The cancerous toxin is the critical role in the course of the disease. So the aim of this article is to clarify the importance in anti-cancerous toxin and the therapeutic principles.