| Background Esophageal cancer is one of the prevalent malignancies,which is divided into Esophageal Adenocarcinoma(EAC)and Esophageal Squamous Cell Carcinoma(ESCC).In recent years,ESCC incidence rate significantly exceeded EAC in more than 90% countries worldwide,of which China remained the highest incidence rate of ESCC.Early diagnosis and timely treatment are essential for the improvement of the prognosis and survival rate of ESCC patients.However,traditional diagnostic methods such as fiber endoscopy and mucosal tissue biopsy have limitations,and conventional tumor markers also meet problems such as lack of sensitivity or specificity.Recently,the correlation of Cysteine Protease Inhibitors(Cystatin,CST)with malignancies has attracted extensive attention.Some scholars believe that there is an important balance between cysteine protease and CST,aberrant regulation of which will be responsible for the occurrence and progression of malignancies.Our previous study has shown cystatin 1(CST 1)is highly expressed in ESCC tissues.As a result,whether CST1 is aberrantly expressed in sera of ESCC patients is worth exploring.By established chemiluminescence immunoassay(CLIA)method,we detected serum CST1 in a small cohort of 50 early ESCC patients,50 benign lesions(EBL)patients,and 50 healthy controls,and found that serum CST1 level in early ESCC group was significantly higher than that in EBL and HC group(P<0.01),which indicates that CST1 detection might contribute to the early diagnosis of ESCC patients.Objectives Based on our previous study,we aim to comprehensively evaluate the detection performance of established chemiluminescence immunoassay for serum CST1;explore the values of early diagnosis,illness assessment,effect monitoring and prognosis judgement of serum CST1 detection for ESCC patients;establish a panel of serum CST1 with conventional tumor antigen markers to further improve the diagnostic sensitivity at high specificity for ESCC patients at early stage.Methods1.Immunohistochemical assay was used to detect the expression of CST1 protein in cancerous tissues and matched paracancerous tissues of 22 early ESCC patients.2.Detection performance of the established CLIA for serum CST1 was evaluated by lineality reference range,detection limitation,accuracy,precision,interference,sample stability and reagent stability.3.By established CLIA method,a large serum sample cohort of 121 patients with early ESCC at TNM 0/I/II phase,101 patients with late ESCC at TNM III/IV phase,107 patients with EBL such as esophageal erosion,esophageal leiomyoma,etc.,and 151 health controls was detected to define the early diagnosis and illness assessment of serum CST1 for ESCC patients.4.Serum CST1 levels of 28 ESCC patients before and after surgery were compared to evaluate the effect monitoring value of serum CST1 for ESCC patients.5.Recurrent ESCC parients after withdrawl of treatment by clinical data retrospection and telephone follow-up were recruited to explore prognosis judgement of serum CST1 detection for ESCC patients.6.By chemiluminescence immunoassay,serum conventional antigen markers including CEA,SCC and CYFRA21-1 were detected to explore their early diagnostic performances for ESCC patients.7.All possible combinations of CST1 with 3 conventional antigen markers including CEA,SCC and CYFRA21-1 were analyzed to establish the optimal combination for the further improvement of diagnostic performance for ESCC patients.Results1.There is a good linear relationship in the range of 6.25-400 U/ml.The detection limitation was 1.35 U/ ml.The average recovery rate was 102.65%(85%-115%).The precisions within batches for low and high CST1 level were4.43% and 1.94%,respectively,all of which were <1/4 TEa.The precisions between batches were 1.39% and 1.90%,respectively,all of which were <1/3 TEa.Hemoglobin and rheumatoid factor had no interference for serum CST1 detection,while bilirubin and triglyceride presented certain interferences for CST1 detection in sera with low CST1 level.Stability evaluation showed serum samples were stably preserved at 4℃ and the detection reagent had good 25 ℃ and 37℃ thermal stability as well as 4 ℃ validity period stability.2.The positive rate of CST1 in ESCC tissues was 81.8%(18/22),while the CST1 expression in matched paracancerous tissues was negative.3.Taking 68.33U/ ml as cutoff value,serum CST1 level and positive rate in early ESCC group were significantly higher than that in EBL and HC groups(P<0.05).The diagnostic sensitivity of CST1 for early ESCC patients were 31.25%at 92.64% specificity,and AUC is 0.654.4.Serum CST1 level in advanced ESCC patients was 81.29±56.17 U/ml,which was significantly higher than 60.08±42.36 U/ml in early ESCC patients(P<0.05).5.Serum CST1 level in 28 ESCC patients after surgery was 37.49±23.98U/ml,which is significantly lower than 53.32±23.37 U/ml in patients before surgery(P<0.05).6.Serum CST1 level in 20 ESCC patients with follow-up recurrence was88.46±50.39U/ml,which was significantly higher than 53.92 ± 37.98 U/ml in no recurrence group(P<0.05).Additionally,serum CST1 level of 50% ESCC patients with follow-up recurrence exceeded normal reference level 68.33U/ml.7.The level and positive rate of CEA in early ESCC group were significantly higher than that in EBL/HC group(P<0.05).The positive rate of CYFRA21-1and SCC in early ESCC group were significantly higher than that in EBL/HC group(P<0.01),while there was no significant difference of the level of CYFRA21-1 and SCC between early ESCC group and EBL/HC group(P>0.05).The diagnostic sensitivity of 3 conventional antigen tumor markers for early ESCC group ranged from 10.81%-29.73%,at >92.0% specificity,of which,SCC showed the highest AUC up to 0.722.8.Among all possible combinations of CST1 with 3 conventional antigen markers,a panel of CST1 with CEA and SCC exhibited the highest AUC up to0.726(95%CI 0.649-0.798),with sensitivity44.59% at specificity 92.0%.Conclusions1.The established chemiluminescence immunoassay has good detection performance for serum CST1.2.Serum CST1 detection has the values of early diagnosis,illness assessment,effect monitoring and prognosis judgement for ESCC patients.3.Individual detection of CEA,SCC and CYFRA21-1 have rather limited value for early diagnosis of ESCC patients,while the combination of CST1 with CEA and SCC might further improve the early diagnostic performance for ESCC patients. |
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