A systematic review of the relation between interleukin-2 schedule and outcome in patients with metastatic renal cell cancer.

In Europe, interleukin 2 (IL-2) is one of the two treatment modalities officially approved for patients with metastatic renal cell cancer. Traditionally, IL-2 has been administered by three different routes: intermittent bolus injection (BIV), continuous intravenous infusion (CIV) and subcutaneous injection (SC). There have been few randomized trials designed to compare these routes of administration. This paper describes a systematic review of the literature in which an attempt has been made to determine which schedule of administration is superior. Heterogeneity of the data makes firm conclusions difficult. It appears that the number of complete remissions (CR) is similar between BIV and SC routes and that these are higher than for CIV schedules. The durability of the CRs induced by BIV appeared superior to those induced by SC IL-2 and definitely higher than with CIV protocols. This analysis highlights some of the difficulties of using evidence-based medicine to determine standard of care when the clinical-trial data are heterogeneous. These data emphasize the importance of randomized clinical trials in determining what should be regarded as optimum therapy.