The relationship of plasma β-endorphins and pain dimensions in primary liver cancer patients using the Chinese Cancer Pain Assessment Tool

Evidence suggests a mind-body link in pain experience. Many studies have focused on the link between endorphins and pain intensity. However, there is a lack of research that examines the bio-psycho-socio-cultural link from a multidimensional perspective in cancer pain experience. Methods: This cross-sectional correlational study investigated the relationship between plasma β-endorphin level (objective variable) and the pain dimensions (subjective variables). Venous blood samples were taken from 76 Chinese primary liver cancer patients by convenience in a cancer centre and plasma β-endorphin levels were measured by radioimmunoassay. The Chinese Cancer Pain Assessment Tool (CCPAT) was employed to assess the pain dimensions which include: functional, psychosocial, pharmacological, emotional, pain beliefs and meanings, pain intensity. Results and Discussion: Sixty-eight men and eight women were recruited the mean age was 49.8 (±12.2) years. Thirty-two (42.1%) patients experienced varying degrees of pain. The mean β-endorphin level was 270.4 (± SEM 11.4)pg/ml. The mean weighted CCPAT scores were 27.8 (±8.9), 14.6 (±2.1), 19.0 (±4.1), 23.1 (±6.4), 70.1 (±8.3) and 0.8 (±1.5) for functional, psychosocial, pharmacological, emotional, pain beliefs and meanings, pain intensity dimensions respectively. Spearman's correlations demonstrated a significant relationship between β-endorphin level and the psychosocial dimension scores (r = -0.25, p = 0.028) in the pain and control groups. Inverse correlations between plasma β-endorphin level and all CCPAT pain dimension scores were found. The results are consistent with those of a previous study by Chung et al. in 2002. Conclusions: Our study suggests that there is a mind-body link in cancer pain experience. Establishment of this link will enhance more accurate pain assessment and provide a basis for multidisciplinary pain interventions, fostering better pain management.