Literature Search Strategy
MEDLINE (1966 through February 2005), EMBASE (1980 through 2005 week 9), and CANCERLIT (1975 through October 2002) databases were searched for relevant papers. MEDLINE was searched using the following medical subject headings: "Carcinoma, renal cell," "kidney neoplasms," "immunotherapy," "interleukin-2," and "interleukin;" EMBASE was searched using the following Excerpta Medica tree terms: "kidney tumor," "kidney cancer," "immunotherapy," and "interleukin 2." In each database, those subject headings were combined with the following disease and treatment-specific text words: "renal cancer," "kidney cancer," "immunotherapy:" "interleukin," and "IL-2." Those terms were then combined with search terms for the following publication types and study designs: randomized controlled trials, controlled clinical trials, meta-analyses, systematic reviews, and practice guidelines.
In addition, the Cochrane Library databases (2004, Issue 4) and the conference proceedings of the American Society of Clinical Oncology (1995-2005) and the American Urological Association (1995-2005) were searched for abstracts of relevant trials. The Canadian Medical Association Infobase (http://mdm.ca/cpgsnew/cpgs/index.asp) and the National Guideline Clearinghouse (http://www.guideline.gov/) were also searched for existing evidence-based practice guidelines.
Relevant articles and abstracts were selected and reviewed by four reviewers, and the reference lists from those sources were searched for additional trials, as were the reference lists from relevant review articles.
Study Selection Criteria
Articles were selected for inclusion in this systematic review if they were fully published reports or abstracts of randomized controlled trials (RCTs) or meta-analyses of randomized controlled trials comparing interleukin-2 (IL-2)–containing treatment regimens to regimens without interleukin-2 in patients with unresectable or metastatic renal cell carcinoma (RCC). Reports were required to provide data on at least one of the following outcomes: survival (i.e., overall, progression-free, or time-to-progression), response rate, toxicity, or quality of life. Reports including non-renal cell carcinoma patients were eligible as long as the outcomes for renal cell carcinoma patients were analyzed separately. Existing systematic reviews or evidence-based practice guidelines relevant to the guideline question were also eligible. Randomized controlled trials that compared either surgery or radiotherapy with interleukin-2 immunotherapy were excluded.