The Correlation Between Salivary α-amylase Activity And Pain Rlieving Scale In Cancer Patients With Bone Metastasis Treated With Radiotherapy

OBJECTIVE:Nowadays, evaluation of pain intensity has relied on subjective assessment tools, Visual analogue scale (VAS) is one of the most commonly used to assess pain intensity because of its higher credibility, However, the VAS is of limited value if patients fail to reliably report,therefore alternative objective assessment methods are clearly preferable. Recently, measurement of salivary biomarkers such as cortisol (SC), a-amylase (SAA) which can be sampled noninvasively, have been evaluated as stress biomarkers. In addition, several reports suggest that psychosocial stress increases the release of salivary a-amylase, which reflects activity of the sympathoadrenal medullary (SAM) system. As painful stimuli activate the SAM and hypothalamic-pituitary-adrenal axis (HPA), salivary a-amylase may reflect pain-associated stress. In this study, we have determined the changes in cancer patients with bone metastasis treated with radiotherapy to discuss the correlation between VAS and SAA activity.METHODS:All cases were diagnosed in Qilu Hospital of Shandong University from June,2010 to March,2011.30 patients (male/female= 13/17, age:63.44±7.29years) with chronic cancerous pain undergoing radiotherapy for cancer pain were recruited. All Patients were located under the analog machine first and then radiated in vitro with X-ray or E-line using the same type of dose fraction radiotherapy:3Gy/f*10,5f/w,DT 30Gy.Heart rate(HR),blood pressure(BP,VAS,SAA,SC were assessed before(do) and 5 times(d5) and 10 times(d10) after the radiotherapy.SAA was measured using a portable analyzer. Then the relationship between VAS and SAA in chronic cancerous pain patients was assessed.RESULTS:The radiotherapy markedly decreased the VAS pain scale from 82.93±9.29 to 31.43±16.73mm (P<0.001) and SAA from 109.40±26.38 to 36.03±19.40U/ml (P <0.001).Moreover, there is a significant correlation between the two measures (P<0.01, r=0.541). HR decreased by 6.5% after radiotherapy, but have no significant correlation with VAS (P>0.05). In contrast, SC and BP didn't change significantly in the study (P >0.05).CONCLUSIONS:Radiotherapy can markedly decreased the VAS pain scale, therefore it's an efficient analgesic mean to cancer patients with bone metastasis. Because there was a significant correlation between VAS pain scale and salivary a-amylase, we suggest that biomarker may be a valuable and sensitive index for the objective assessment of pain intensity. In addition, SAA, which reflects activity of the SAM, can be a promising candidate for a reliable, noninvasive marker of psychosocial stress.