Methadone Hydrochloride as First-Line Therapy in Treating Patients With Chronic Neuropathic Cancer Pain

DISEASE CHARACTERISTICS:

* Patients diagnosed with cancer and experiencing chronic neuropathic pain syndrome

  * Pain syndrome diagnosed by the investigator
  * Pain syndrome related to the effects of cancer or its treatment (i.e., chemotherapy, radiotherapy, and surgery)
  * Meets 1 of the following criteria:

    * Need to be started on strong opioids
    * Require an increase in opioid dose and are currently taking ≤ 75 mg of total daily dose of oral morphine equivalent
* Experiencing pain for ≥ 4 weeks with an average pain score of ≥ 4 or a worst pain score of ≥ 5 (using the 0-10 Brief Pain Inventory Scale) during the past 24 hours
* Requires strong opioids to control pain and is using an oral morphine-equivalent dose of 0-75 mg per day, on average, including breakthrough analgesia, within the past 3 full calendar days
* Mixed pain syndrome allowed provided the neuropathic component is the predominant pain
* Meets 1 of the following criteria:

  * Receiving concurrent chemotherapy but the chronic neuropathic pain is not related to this treatment and is not expected to improve or worsen because of this therapy
  * Received prior chemotherapy but discontinued treatment, has not received chemotherapy within the past 7 days, and no further chemotherapy is planned
  * No prior chemotherapy

PATIENT CHARACTERISTICS:

* Karnofsky performance status 40-100%
* ALT and AST ≤ 3 times upper limit of normal (ULN)
* Creatinine ≤ 2 times ULN
* No other known laboratory abnormality that, in the investigator's opinion, would contraindicate study participation
* Not pregnant or nursing
* Fertile patients must use effective contraception
* Mini-Mental State Examination score ≥ 25/30
* Able to speak, read, and write in either English or French
* Willing to complete study diary and questionnaires
* Available for study treatment and follow up (i.e., within reasonable geographical limits of the participating center)
* Able to swallow and tolerate oral medications
* Patients with prior exposure to methadone hydrochloride must be able to tolerate it
* No intractable nausea and vomiting
* No presence or history of unstable disease or condition that would, in the investigator's opinion, preclude patient participation in study treatment, such as:

  * Head injury
  * Increased intracranial pressure
  * Uncontrolled seizures
  * Uncontrolled asthma
  * Decompensated chronic obstructive pulmonary disease
  * Untreated prostate hypertrophy
  * Acute abdominal conditions
  * Untreated hyperthyroidism and Addison disease
  * Increased cerebrospinal fluid pressure
  * Urethral stricture
  * Severe cardiac arrhythmias (especially prolonged QT interval)
  * Symptomatic hypotension
  * Toxic psychosis
  * Cor pulmonale
  * Sleep apnea
  * Severe obesity
  * Kyphoscoliosis
  * Myxedema
  * Central nervous system depression
  * Coma
* No history of significant alcohol, analgesic, or narcotic substance abuse within the past 6 months
* Able physically and mentally to answer questions and comply with study treatment
* No patient who lives alone and cannot access at least 1 caregiver who can monitor on a daily basis at home

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* More than 3 weeks since prior radiopharmaceutical treatment or radiotherapy
* Concurrent co-analgesics and medications that can affect methadone hydrochloride metabolism allowed provided patients have been on a stable dose for the past 3-5 days and ≥ 5 half lives have passed since any change in dose
* Not scheduled to start chemotherapy during the study treatment
* Not planning on starting or discontinuing medication associated with modified methadone hydrochloride clearance during study treatment
* No concurrent therapeutic procedure that is likely to influence pain intensity during the study period
* No concurrent other opioid medications
* No other concurrent methadone hydrochloride