Ketamine Hydrochloride and Best Pain Management in Treating Cancer Patients With Neuropathic Pain

DISEASE CHARACTERISTICS: * Histologically confirmed cancer * Index neuropathic pain ≥ 4 on 0-10 (as defined by Leeds Assessment of Neuropathic Symptoms and Signs) that is related to underlying malignancy or resulting from treatment received for this malignancy * McGill Sensory Scale Score \> 5 * Received a trial of an adjuvant analgesic (gabapentin or amitriptyline or both) PATIENT CHARACTERISTICS: * Life expectancy ≥ 2 months * Fertile patients must use effective contraception * Able to comply with study procedures * Diastolic blood pressure ≤ 100 mm Hg at screening * No seizures in past 2 years * Not actively hallucinating * No cerebrovascular disease (strokes) * No psychotic disorders or cognitive impairment PRIOR CONCURRENT THERAPY: * See Disease Characteristics * At least 6 weeks since prior and no concurrent chemotherapy or radiotherapy that is likely to affect neuropathic pain * No change in tumoricidal treatment during the period of the study that is likely to alter pain during the course of the study * No concurrent class I antiarrhythmic drugs