Inhaled Morphine Compared With Morphine By Mouth in Treating Cancer Patients With Breakthrough Pain

DISEASE CHARACTERISTICS: Opioid-sensitive breakthrough pain due to cancer More than 1 episode daily Oral opiate dose of no more than 100 mg of morphine No known allergy to morphine or other opioids No known CNS excitatory response to morphine or other opioids No unstable persistent morbidity due to prior chemotherapy or radiotherapy PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-3 Life expectancy: More than 3 months Hematopoietic: Not specified Hepatic: Bilirubin less than 2.0 mg/dL AST less than 82 U/L ALT less than 72 U/L Renal: Creatinine less than 1.5 mg/dL Pulmonary: No significant history or recent exacerbation of bronchial asthma No chronic obstructive pulmonary disease No significant pulmonary pathology that would preclude study Other: No history of substance abuse, including alcohol, within the past 2 months No other condition that would preclude study Not pregnant or nursing Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: Recovered from prior chemotherapy No concurrent chemotherapy that would cause toxicity (e.g., emesis) Endocrine therapy: Not specified Radiotherapy: Recovered from prior radiotherapy No concurrent radiotherapy that would cause toxicity (e.g., emesis) Surgery: Not specified Other: At least 30 days or 5 half-lives (whichever is longer) since prior investigational drug No concurrent MAO inhibitors