A critical examination of the foundations of immunotherapy for cancer.

It is argued that immunotherapy (IMTH) for cancer, as well as the theory of cancer immunogenicity on which it rests, derives no secure foundation either from clinical observations or from experimental study of valid animal tumour models. Discouraging clinical observations include: the long history of failure of IMTH; the rejection of IMTH for choriocarcinoma--a true allograft in the patient; the extreme rarity of spontaneous regression, and progressive discrediting of the theory of immunosurveillance; the high frequency of nodal metastasis; and the failure to demonstrate a tumour-specific antigen in man. The great majority of animal tumours used for experimental studies of IMTH display artefactual immunogenicity associated with their mode of induction or conditions of transplantation and cannot be accepted as valid models of clinical cancer. The author reviews his total failure to demonstrate immunogenicity or successful IMTH using a wide range of animal tumours from which known laboratory artefacts have been strictly excluded. The inordinate promotion of tumour immunology and IMTH in recent years is attributed to unfortunate sociological influences encouraging premature assertion of clinical relevance from experimental research.