Endoscopic ultrasound-guided injectable therapy for pancreatic cancer: A systematic review

BACKGROUND: Given the low survival rate in pancreatic cancer, new therapeutic techniques have been explored, especially for unresectable or borderline resectable disease. Endoscopic ultrasound (EUS) provides real-time imaging and minimally invasive access for local and targeted injection of anti-tumor agents directly into the pancreatic tumor. Limited studies have been reported using this technique for the treatment of pancreatic ductal adenocarcinoma (PDAC). AIM: To evaluate the progress made with EUS-guided injectable therapies in the treatment of PDAC. METHODS: All original articles published in English until July 15, 2021, were retrieved via a library-assisted literature search from Ovid Evidence-Based Medicine Reviews and Scopus databases. Reference lists were reviewed to identify additional relevant articles. Prospective clinical studies evaluating the use of EUS-guided injectable therapies in PDAC were included. Studies primarily directed at non-EUS injectable therapies and other malignancies were excluded. Retrieved manuscripts were reviewed descriptively with on critical appraisal of published studies based on their methods and outcome measures such as safety, feasibility, and effectiveness in terms of tumor response and survival. Heterogeneity in data outcomes and therapeutic techniques limited the ability to perform comparative statistical analysis. RESULTS: A total of thirteen articles (503 patients) were found eligible for inclusion. The EUS-injectable therapies used were heterogeneous among the studies consisting of immunotherapy (n = 5) in 59 patients, chemotherapy (n = 1) in 36 patients, and viral and other biological therapies (n = 7) in 408 patients. Eleven of the studies reviewed were single armed while two were double armed with one randomized trial and one non-randomized comparative study. Overall, the included studies demonstrated EUS-guided injectable therapies to be safe and feasible with different agents as monotherapy or in conjunction with other modalities. Promising results were also observed regarding their efficacy and survival parameters in patients with PDAC. CONCLUSION: EUS-guided injectable therapies, including immunotherapy, chemotherapy, and viral or other biological therapies have shown minimal adverse events and potential efficacy in the treatment of PDAC. Comparative studies, including controlled trials, are required to confirm these results in order to offer novel EUS-based treatment options for patients with PDAC.