World Health Organization (WHO) three-step ladder oral analgesic program for managing cancer pain. Source: Chapter 48. Pain Management and Symptom Control, The MD Anderson Manual of Medical Oncology, 2e Citation: Kantarjian HM, Wolff RA, Koller CA. The MD Anderson Manual of Medical Oncology, 2e; 2011 Available at: http://accessmedicine.mhmedical.com/DownloadImage.aspx?image=/data/books/kant2/kant2_c048f002.gif&sec=39909346&BookID=379&ChapterSecID=39902080&imagename= Accessed: December 30, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved