Endothelin-1 (ET-1) may be involved in driving pain in patients with advanced cancer. However, a few studies focus on the role of ET-1 in breakthrough pain (BP). The aim of this pivotal study was to explore the correlation between the plasma (ET-1) level and BP intensity. A total of 40 patients were enrolled in the study, and they were divided into two groups: BP group and non-BP group. Moreover, 20 healthy adults were used as the normal control group. Pain intensity was measured using visual analog scale (VAS) scores of 1-10. Plasma ET-1 levels were detected by an ET radioimmunoassay kit. Subsequently, the correlation of ET-1 level with the VAS score and cancer types was analyzed by Pearson's correlation coefficient. The plasma ET-1 level in the BP group (35.31±8.02 pg/mL) was higher than that in the non-BP group (29.51±6.78 pg/mL) and the normal control group (24.77±10.10 pg/mL, P<0.05). In addition, the VAS score in the BP group (7.45±0.82) was higher than that in the non-BP group (2.80±1.23, P<0.05). The plasma ET-1 level was positively correlated with the VAS score of the BP group (Pearson's r=0.42). There was no significant correlation between the plasma ET-1 level and VAS score of the non-BP group (Pearson's r=-0.22) or/and cancer types (P>0.05). The elevated plasma ET-1 levels were positively related to BP, and targeting ET-1 may provide a novel pain-reducing therapeutic treatment in BP.
Keywords: background pain; cancer types; correlation; visual analog scale.