Inclusion Criteria

DISEASE CHARACTERISTICS: Chronic visceral or somatic pain due to cancer or prior cancer
therapy No pain primarily classified as neuropathic or unknown in nature Required opioid
analgesic at least 5 days/week for at least 2 weeks prior to study Expectation of
continued requirement for daily opioid medication (morphine sulfate, oxycodone, or
hydromorphone)

PATIENT CHARACTERISTICS: Age: Legal age and over Performance status: Karnofsky 60-100%
Life expectancy: At least 4 months Hematopoietic: Platelet count at least 40,000/mm3 No
platelet function disorder Hepatic: No known significant hepatic insufficiency Renal:
Creatinine less than 1.5 mg/dL BUN less than 1.5 times upper limit of normal Creatinine
clearance greater than 50 mL/min No known renal insufficiency Gastrointestinal: No
diagnosis of esophageal, gastric, pyloric channel, or duodenal ulceration within the past
30 days No history of esophageal or gastric cancer No intractable nausea or vomiting No
inability to swallow tablets or to tolerate oral medication Other: Weight at least 50 kg
No AIDS or AIDS-related cancers No history of hypersensitivity to cyclooxygenase
inhibitors (e.g., NSAIDs or specific COX-2 inhibitors) or opiates No significant alcohol,
analgesic, or narcotic substance abuse within the past 6 months No history of unstable
disease or condition that would preclude study Not pregnant or nursing Negative pregnancy
test Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: At least 3 weeks
since initiation of new chemotherapy agent No concurrent participation in an
investigational chemotherapy trial Endocrine therapy: At least 2 weeks since initiation of
corticosteroids as an analgesic adjuvant Radiotherapy: At least 4 weeks since prior
radiopharmaceutical therapy or radiotherapy No concurrent radiopharmaceutical therapy or
radiotherapy Surgery: No concurrent therapeutic procedure (e.g., surgery or biopsy) that
would affect pain intensity Other: No prior participation on this study At least 30 days
since prior investigational agent At least 30 days since prior treatment for esophageal,
gastric, pyloric channel, or duodenal ulcer At least 8 weeks since initiation of
bisphosphonates At least 2 weeks since anticancer therapy that would affect study
evaluation At least 2 weeks since initiation of antidepressants, anti-epilepsy drugs, or
antihistamines as an analgesic adjuvant At least 5 half-lives since prior specific COX-2
inhibitors or non-steroidal anti-inflammatory drugs (NSAIDs) No concurrent other
investigational agent No concurrent anticancer therapy that would affect study evaluation
No concurrent other analgesics, specific COX-2 inhibitors, or NSAIDs except as
specifically permitted on study Concurrent acetaminophen less than 2 g/day allowed if
given 2 days or fewer per week Concurrent acetylsalicylic acid no greater than 325 mg/day
allowed