Five RCTs (n=302) were included.
Only one study was judged to be of adequate quality. Three studies were double-blinded and two were unblinded. Only one study described the method and generation of allocation concealment.
Pain control: the mean baseline VAS score was 5.0. The mean VAS pain score was statistically significantly lower in patients who received NCPB at 4 weeks (WMD -0.50, 95% CI: -0.85, -0.15, p=0.005; 3 studies, 117 patients) and at 8 weeks (WMD -0.60, 95% CI: -0.82, -0.37, p<0.00001; 4 studies, 204 patients) compared with the control group. The mean VAS pain score was also
lower in patients who received NCPB after 2 weeks, but the difference was not statistically significant (random-effects WMD -0.34, 95% CI: 1.03, 0.34, p=0.33; 3 studies, 126 patients). A funnel plot at 8 weeks showed no asymmetry, suggesting the absence of publication bias.
Opioid use (3 studies): the mean daily opioid use was statistically significantly lower in patients who received NCPB at 2 weeks (WMD -39.99 mg, 95% CI: -60.08, -19.91, p<0.0001), 4 weeks (WMD -53.69, 95% CI: -79.65, -27.73, p<0.0001) and 8 weeks (WMD -80.45, 95% CI: -134.66, -26.24, p=0.0004) compared with the control group.
QOL: one study reported no significant difference in the FACT-PA between the NCPB and control groups. The other study reported no consistent differences between treatment groups
Survival: there was no statistically significant difference in survival between the NCPB and control groups at 8 weeks (based on 4 studies).
Adverse events: the only significant difference in adverse events was a significant reduction in constipation in the NCPB group compared with the control group (RR 0.67, 95% CI: 0.49, 0.91, p=0.01).