Determination of the diagnostic potential of research methods in the differentiation of pancreatic cancer and chronic pancreatitis based on evidence-based medicine

Background. Currently, the use of the principles of evidence-based medicine is an integral part of assessing the effectiveness and safety of modern technology for the diagnosis and treatment of any disease or clinical condition. Differential diagnosis of pancreatic cancer and chronic pancreatitis is one of the most controversial issues in surgical pancreatology. The reduced number of cases of resectable pancreatic cancer indicates the need to develop programs for the differentiation of these pathologies with the wide implementation of modern diagnostic methods. Purpose − to compare the results of diagnostic methods (which are standardly used in accordance with clinical guidelines for the diagnosis of chronic pancreatitis) based on evidence-based medicine and quantitative assessments of their specificity, sensitivity, and general accuracy in terms of the differential diagnosis of chronic pancreatitis and pancreatic cancer in order to determine the most significant results for the differentiation of these pathologies. Materials and methods. The results of diagnostic methods were compared in 80 patients, among them 38 (47.5%) had pancreatic cancer, and 42 (52.5%) − chronic pancreatitis with predominant lesion of the pancreatic head. The patients underwent general clinical blood and urine tests, biochemical blood tests, and the following procedures and examinations available in the clinic: ultrasound examination of the abdominal organs, spiral computed tomography, fibrogastroduodenoscopy, endoscopic retrograde cholangiopancreatography, magnetic resonance imaging, CA 19-9 tumor marker test, ultrasound-guided percutaneous puncture of the pancreas, aspiration of pancreatic juice, urgent intraoperative biopsy, and histological examination of surgically resected areas of the pancreas. Based on the received data, we performed a comparison of their quality, accuracy, and informativeness. Results. Ultrasound imaging is a screening method for suspected pancreatic cancer, however, the overall accuracy, sensitivity, and specificity of the method are quite low (82.5%, 76.32%, 88.10%, respectively). When analyzing the qualitative characteristics of endoscopic retrograde cholangiopancreatography, the overall accuracy, sensitivity, and specificity indicators for the differential diagnosis of pancreatic cancer were 71%, 78.6%, and 63.3%, respectively. The interval assessment of the accuracy of the method of transcutaneous biopsy of the pancreas aimed at determining chronic pancreatitis was (34.9; 96.8)%; for pancreatic cancer – (8.5; 75.5)%. The interval assessment of the accuracy of the method of endoscopic aspiration of pancreatic juice for chronic pancreatitis was (6.8; 93.2)%; for pancreatic cancer – (19.4; 99.4)%. An increase in the level of CA 19-9 was found in 40.5% of patients (CI95% from 27.0% to 55.5%), while the average level was significantly higher in pancreatic cancer. The level of the CA 19-9 tumor marker depended on the size of the tumor and the spread of the process, and during the dynamic observation in the settings of treatment, it had a tendency to decrease, which indicated chronic pancreatitis. The significance of intraoperative morphological verification of the diagnosis of pancreatic cancer in histological examination was 98%, in cytological examination – 95.3%, in 4.7% urgent intraoperative biopsy was questionable. In all examinations, the surrounding tumor tissue showed a morphological pattern of chronic pancreatitis, in 36 (88%) cases – with foci of metaplasia and intraductal neoplasia of the epithelium, which can be considered as a background for the development of intraductal adenocarcinoma. At the same time, cancerous occlusion of the ducts led to their expansion above the point of narrowing with pronounced fibrous changes and inflammatory reaction of the stroma that was accompanied by widespread atrophy of the parenchyma. Conclusions. On the basis of evidence-based medicine, it was established that spiral computed tomography is the most informative method for the differential diagnosis of pancreatic cancer with chronic pancreatitis, with an overall accuracy of 92.2%, sensitivity of 89.2%, and specificity of 95%. The low qualitative indicators of ultrasound diagnostics can be increased due to its complex combination with the CA 19-9 tumor marker test with an overall accuracy of 92.3%, with sensitivity and specificity of 95% and 91%, respectively, which is significantly different from such indicators when the method was used separately (82.5%, 76.3%, and 88.1%, respectively). In the cases when the complex combination of endoscopic retrograde cholangiopancreatography with the measurement of the level of the CA 19-9 tumor marker was used, the overall accuracy of the method was 95.2%, with sensitivity of 95% and specificity of 95.5%, which is significantly different from such indicators obtained when the method was used separately (71%, 78.6% and 63.3%, respectively). Advances in modern imaging methods cannot replace histological examination as the «gold standard» for the correct determination of the morphological substrate of these pancreatic lesions.