Treatment for Chronic Pain in Patients With Advanced Cancer

DISEASE CHARACTERISTICS: * Histologically or cytologically proven advanced cancer with chronic pain * Cancer pain requiring strong opioids having an average pain score of less than 6/10 on the visual analog scale within last 24 hours * Pain managed by a stable maintenance dose of MS-Contin formulation of morphine for at least 2 days with no more than 2 breakthrough immediate release morphine doses per 24 hours * Pain that is expected to be controlled by a stable and adequate total daily dose of sustained release morphine for the first 7 days of the study PATIENT CHARACTERISTICS: Age: * 16 and over Performance status: * Not specified Life expectancy: * At least 2 months Hematopoietic: * Not specified Hepatic: * SGOT or SGPT no greater than 3 times upper limit of normal (ULN) * No liver disease Renal: * Creatinine no greater than 2 times ULN * No kidney failure Pulmonary: * No clinically significant respiratory depression * No severe obstructive airway disease Other: * Fluent in English or French * No known hypersensitivity or allergy to study medications or components or other multiple drug allergies * Normal cognition defined by the Folstein Mini-Mental State Questionnaire (at least 24/30 correct) PRIOR CONCURRENT THERAPY: Biologic therapy: * Not specified Chemotherapy: * At least 14 days since prior chemotherapy Endocrine therapy: * Concurrent steroids allowed Radiotherapy: * At least 14 days since prior analgesic radiotherapy Surgery: * Not spec…