The lack of immunogenicity of naturally occurring tumors is often understood in terms of a suboptimal condition in the tumor microenvironment to generate protective immunity, regulatory T-cell activity, dendritic cell dysfunction, production of suppressive factors such as IL-10, or changes in the pattern of antigen expression [1,3,26], but so far there was no example of complete suppression of tumor antigen expression, especially if this antigen is the major transforming protein. This evidence concerns the gene IL10 and neoplasm.