Growth of human tumors in cortisone-treated laboratory animals: the possibility of obtaining permanently transplantable human tumors.

A preliminary paper reported that human neo plasms, implanted as either a suspension of cells or a fine mince, often proliferated extensively for 810 days in the subcutaneous tissues of adult, x-radiated heterologous hosts before changes asso ciated with regression occurred; they did not sur vive in nonirradiated animals (2). Subsequently, it was noted that human tissues, similarly implanted in x-radiated rats of weanling age, could grow progressively for 12-14 days or longer (3, 4), a period which allowed the more vigorously growing tumors to be of practical value for the testing of chemotherapeutic agents (6). More recently, it was learned that human cancer cells showed a higher percentage of "takes" and proliferated con siderably longer in x-radiated weanling rats treated with cortisone than in hosts which had re ceived roentgen treatment alone (5). The present paper is concerned with observations on the growth and serial transplantation of human tumors in both x-radiated and nonirradiated ani mals (rats and hamsters) treated with cortisone. The findings have been favorable enough so that the ultimate goal of obtaining one or more human neoplasms that can be maintained as serially transplantable tumors in large numbers of labora tory animals, seems in sight.