Immunologic approach to cancer therapy.

The resistance that many cancer patients show to the progress of their disease, attested to by well documented cases of spontaneous regressions as in neuroblastoma, hypernephroma, choriocarcinoma and malignant melanoma, and the long-term dormancy of multiple metastases seen particularly after removal of a primary mass, can be explained only by host defense mechanisms. Attemps at immunotherapy over the years are reviewed and new directions are presented.