A Efficacy and Safety Trial of Controlled Release (CR) Morphine in Cancer Patients

Inclusion Criteria: * The patient has stable strong opioid use equipotent to 30-240 mg oral morphine sulphate daily for a minimum of 2 weeks prior to entering the run-in phase. * The patient has opioid-sensitive pain caused by active cancer. * The patient is aged minimum 18 years. Exclusion Criteria: * The patient has a life expectancy less than 2 months. * The patient has received chemotherapy or radiation therapy less than 4 weeks prior to entering run-in phase * Patients with medical conditions contraindicating morphine treatment * The patient has hepatic disease or impaired kidney function * The patient is taking monoamine oxidase inhibitors (MAOIs) or has taken a MAOI within two weeks prior to entering baseline. * The patient is taking other opioid agonists or antagonists, zidovudine or cimetidine.