On immunosurveillance in human cancer.

The extraordinarily high incidence of cancers of many different varieties--carcinomas and lymphomas--in organ-transplant patients being maintained for long periods of time with immunosuppressive drugs is briefly reviewed. The role of immunosurveillance as a primary defense mechanism against cancer in human beings is consistent with these observations and is in need of further investigation. Conceivably, this mechanism may play a somewhat different role in humans from what has been observed in most experimental animal models.