Value of pancreatic cyst fluid SPINK1 and glucose in differentiating potentially malignant cysts from those of benign nature: A prospective cohort study.

Background: Diagnosis of malignant pancreatic cystic lesions (PCLs) is challenging as there is no investigation that offers both high diagnostic sensitivity and specificity for a definite diagnosis. Accurate diagnosis of cyst type is vital in order to not miss opportunities for early treatment of potentially malignant lesions and to avoid unnecessary surgeries. Serine protease inhibitor Kazal type I (SPINK1) and glucose are promising cyst fluid markers for differentiation of mucinous from non-mucinous cysts. We aim to validate the value of SPINK1 and glucose in detecting potentially malignant PCLs.

Methods: A prospective study was conducted on 80 patients presenting with PCLs. Endoscopic ultrasound (EUS) evaluation of detailed cyst morphology and EUS with fine needle aspiration (FNA) were done. Fluid analysis for carcinoembryonic antigen (CEA), glucose and SPINK1 and cytopathology were done. We compared these data with the final diagnosis based on cytopathological and postoperative histopathological examination.

Results: Cyst fluid SPINK1 was significantly higher in malignant or potentially malignant cysts compared to benign cysts (0.91 vs 0.47 ng/ml; P = 0.001). Also, glucose was significantly lower in malignant or potentially malignant cysts compared to benign cysts (21.5 vs 68.5 mg/dl; P = 0.0001). Glucose and SPINK1 had the best sensitivity and specificity for differentiating mucinous from non-mucinous cysts with 84.78% and 73.53% (AUC 0.76; 95% CI [0.65-0.88]; cutoff value = 42 mg/dl), and 70.59% and 65.22% (AUC 0.72; 95% CI [0.64-0.86]; cutoff value = 0.58 ug/L) respectively. CEA level >192 ng/ml, high SPINK1 level and lymph node enlargement were the independent predictors of malignant cysts.

Conclusion: Cyst fluid SPINK1 and glucose are promising diagnostic markers for the diagnosis of potentially malignant PCLs.