A prospect on cancer immunology.

There are several factors involved in studying cancer immunology. For convenience, those factors can be consolidated into two. Firstly, no definite tumor-specific or -associated antigen has been ascertained as yet, except for certain types of tumor. Secondly, there is no definite pattern of immune response of the host against weak antigenic tumor cells. Nobody knows as to what is the nature of the tumor-specific antigen even if it exists, and nobody knows the escape mechanism of tumor cells from the immune defence of the host. There have been a number of approaches for cancer immunotherapy, but so far there has been no definite answer as to whether immunotherapy is a promising approach for cancer treatment. In this review, cancer immunology is divided into three separate subjects. The first of these is tumor antigen; the second, the immune response against tumor antigen; and the third, methods of attacking tumor cells by immunological means including how to increase the antigenicity of tumor cells (xenogenization), and how to increase the immune response of the host (immunotherapy).