Patients
cancer, cancer pain, pain
CANCER
Patients were eligible for this study if they had been diagnosed with cancer, had an estimated survival of ≥ 3 months from the start of study drug administration, were currently using non-opioid analgesics (nonsteroidal anti-inflammatory drugs [NSAIDs] or acetaminophen [paracetamol]), had not previously used an opioid analgesic, and the physician deemed it necessary to start tramadol to manage cancer pain. Patients used a 100-mm visual analog scale (VAS) to assess their pain at rest on study days − 2, − 1, and 1 (where study day 1 was the day of starting treatment); only patients with a score of ≥ 25 mm averaged over the 3 days were eligible for the study. Other eligibility criteria included patients treated in an inpatient or outpatient setting, age ≥ 20 years, and adequate liver and renal functions. The major exclusion criteria are listed in the Supplementary Methods.