During Phase 2, patients requiring =96 mg OROS® hydromorphone HCL every 24 hours converted to a once-daily dosing OROS® hydromorphone HCL dose at approximately a 5:1 morphine to hydromorphone equivalent ratio. OROS® hydromorphone HCL dose titration (25-100% baseline dose) was allowed every 2 days to achieve stabilization. OROS® hydromorphone HCL dose reduction was allowed during Phases 2 and 3 for opioid-related adverse events (AEs). Rescue medication, Dilaudid IR (immediate release) was allowed during all 3 phases. During Phase 3, patients attended 4 weekly study visits to provide diary information about study medication and rescue medication usage, daily pain relief scores and adverse events, and to receive weekly supplies of study medications. OROS® hydromorphone HCL tablets of 8,16, 32, or 64 mg depending on Phase I stable baseline oral or transdermal opioid medication, 2-7 days; study drug dose titration was allowed every 2 days to achieve stabilization in Phase II, 3-14 days; Phase III , maintenance therapy phase 28 days; study drug dose reduction was allowed during Phase 2 and 3 for opioid-related adverse events. Rescue medication of Dilaudid IR (immediate release) 2, 4, 8mg tablets were allowed during all phase.