Regression of cancer following surgery.

Postsurgical tumor regressions are rare but well-recognized entities. The causes of such phenomena are unknown but probably are multiple. Regression of any tumor must ultimately come about by changes in the host-tumor interaction which suddenly becomes unfavorable for tumor growth. This is likely a manifestation of changes in the immunocompetence of the host. There are many variables influencing the host-tumor interaction, and the study of tumor immunology is stil in its infancy. It is through the exploration and investigation of basic mechanisms of the immunology of cancer that the most potentially fruitful associations between tumor growth or regression and surgical manipulations may be made and applied to the treatment of cancer patients.