The WHO analgesic ladder for cancer pain control, twenty years of use. How much pain relief does one get from using it?

Introduction: Pain is a major problem in the treatment of patients with cancer. This article reviews studies concerning evaluation of patients with cancer pain treated according to The World Health Organization (WHO) analgesic ladder. Materials and methods: Systematic search of PUBMED, MEDLINE, EMBASE, LILACS, BDENF, and OVID and a hand search of reference lists and textbooks from 1982 to 2004 were performed. Result: Analgesia was considered adequate in 45 to 100% of patients analyzed in the studies. Conclusion: However, the evidence that they provide is insufficient to grant the effectiveness of the WHO guidelines because a controlled clinical trial of this intervention has never been published.