BACKGROUND: We studied the influence of interleukin-2 (IL-2) therapy on tumor growth and prevention of metastasis in metastatic, hormone-refractory prostatic carcinoma (PCa) in an animal model orthotopically (ortho) and subcutaneously (s.c.). MATERIALS AND METHODS: 75 juvenile male Copenhagen rats were divided into five groups of 15 rats each. MatLyLu-PCa (MLL) was implanted ortho (n = 30) in 2 groups or s.c. (n = 30) in 2 groups and were treated locally at the tumor site with micro-osmotic pumps. The rats in 2 groups received IL-2 pumps with 36 x 10(6) IU of IL-2 and the rats in 2 other groups were treated with pumps delivering albumin only as a control. The rats in the last group received ortho MLL and s.c. IL-2 (n = 15). Survival time was then monitored. RESULTS: Prostatic tumor was found in all ortho animals. Additionally lymphogenic and pulmonary metastasis was found in all animals. The orthotopic and s.c. IL-2-treated groups showed a statistically significantly increased survival compared with the orthotopic and s.c. albumin-treated groups. When treating the ortho MLL with s.c. IL-2 there was still a statistically significant longer survival than in the control groups. CONCLUSION: IL-2 therapy significantly reduces tumor growth of rats with metastatic, hormone-refractory prostatic cancer MatLyLu.
