The efficacy of low-dose transdermal fentanyl in opioid-naïve cancer patients with moderate-to-severe pain

BACKGROUND/AIMS Little is known about the efficacy of low-dose transdermal fentanyl (TDF) patches in opioid-naïve patients with moderate-to-severe cancer pain. METHODS This study had an open-label, prospective design, and was conducted between April 2007 and February 2009 in seven tertiary cancer hospitals; 98 patients were enrolled. TDF was started using a low-dose formulation (12.5 µg/hr), and the dose was adjusted according to the clinical situation of individual patients. Pain intensity, the TDF doses used, and adverse events (AEs) were monitored over 4 weeks. Data were analyzed using the intent-to-treat and per-protocol principles. RESULTS Of the 98 patients enrolled, 64 (65%) completed the study. The median pain intensity decreased from 6.0 to 3.0 (p < 0.001) at the follow-up visit. The efficacy of low-dose TDF on pain relief was consistent across groups separated according to gender (p < 0.001), age (p < 0.001), metastasis (p < 0.001), previous treatment (p < 0.001), and baseline pain intensity (p < 0.001). The decrease in pain intensity was significantly greater in the severe group compared with the moderate group (mean ± SD, 5.10 ± 2.48 vs. 2.48 ± 1.56; p < 0.001). TDF dose (27.8 µg/hr vs. 24.8 µg/hr, p = 0.423) and the mean treatment time (7.5 days vs. 7.9 days, p = 0.740) required for pain control were not different between the two pain-intensity groups. Patients had AEs of only mild or moderate intensity; among these, nausea (38%) was the most common, followed by vomiting (22%) and somnolence (22%). CONCLUSIONS Low-dose TDF was an effective treatment for patients with cancer pain of moderate-to-severe intensity. Further randomized trials assessing the efficacy of TDF for severe pain and/or optimal starting doses are warranted.