Because of the less adverse effects, especially for constipation, transdermal fentanyl might be easier to improve QOL. In present study, 6 trials reported data on QOL and showed either transdermal fentanyl or sustained-release oral morphine improved QOL of cancer patients [9, 14, 17, 32–34]. Especially, one of trials supported more patients got better Daporinad mouse QOL after sustained-release oral morphine transferred to transdermal fentanyl [34]. Cost effectiveness was not an endpoint in the present

systematic review, but it was a valuable index to evaluate a drug for clinical use. 2 out of selected trials reported data about cost effectiveness that transdermal fentanyl had higher expenditure to control certain pain than oral morphine [35, 36]. However, we MK-1775 concentration should keep in mind that cost effectiveness was affected by many factors in fact and only 2 out of 32 trials reported data about cost effectiveness when we concluded cost effectiveness was higher in transdermal fentanyl. Similar with European and American data [4–6], our data also showed that both transdermal fentanyl and find more sustained-release oral morphine were effective in treating stable moderate-severe cancer pain in Chinese population with less

adverse effects for transdermal fentanyl. However, two differences should be pointed out. First, QOL was only analyzed in our study, and data suggested that transdermal fentanyl potentially improved QOL of cancer pain patients and resulted in better compliance compared with oral morphine. Second, more patients were included in the present systematic review and all

patients were Chinese. To explain the results reasonably, several issues should be considered as follow. First, the data source was extracted from abstracted data and not individual patient data (IPD). In general, an IPD-based meta-analysis would give a more robust estimation for the association; therefore, we should interpret the results with care, especially for a positive result. Clearly, further investigations using IPD should be conducted to examine the main end points. Second, all selected trials were cohort studies, which is not most suitable clinical trial to explore the difference of two drugs. Third, 5 FU heterogeneity existed among the trials when pooled analysis of adverse effects (constipation and nausea/vomiting), fortunately, the data was not materially changed in sensitivity analysis. Fourth, side effects seemed to be lower in our selected trials compared with clinical practice. We thought that these results might be explained in two aspects of small sample in single trial and better tolerance in Chinese population. At last, transdermal fentanyl takes 12-24 hours for serum levels to stabilize after starting the patch and dose increment was trouble in clinic practice, so it is less flexible and needs to be used with caution in patients with unstable pain.