Three years ago, the successful immunotherapy of a transplantable spontaneously metastasizing mammary adenocarcinoma 13762 in female Fischer 344/N rats with xenogeneic or syngeneic Immune RNA was demonstrated in our l a b o r a t~r y .~~ I n this model, when growing primary tumor transplants are surgically excised 18 days after transplantation, local recurrence does not occur. However, all animals go on to die of metastases to lung and other organs