Neo-Adjuvant Treatment in Primary Resectable Pancreatic Cancer: A Systematic Review and PRISMA-Compliant Updated Metanalysis of Oncological Outcomes

SIMPLE SUMMARY: Pancreatic adenocarcinoma is the fourth leading cause of cancer-related death in industrialized countries. In locally advanced and borderline resectable pancreatic cancer, neoadjuvant therapy (NAT) has been shown to be effective in eliminating potentially circulating tumor cells and distant micrometastases, shrinking local tumors, and identifying high-grade malignancies that do not benefit from surgery. However, in patients with resectable pancreatic adenocarcinoma, who represent 20% of new diagnoses and for whom US followed by adjuvant chemotherapy is the standard of care, NAT is controversial because it carries several potential drawbacks that may prevent surgery and increase the risk of clinical deterioration. Randomized clinical trials, retrospective studies, and a few systematic reviews and meta-analyses reported controversial results, and although the safety and feasibility of such an approach are supported, a wider implementation is still a matter of debate. Considering the different methodological approaches (RCTs vs. retrospective studies), the difficulty in providing high-quality evidence due to small patient numbers, and the emergence of new evidence, an update of the current evidence seems essential to help clinicians and researchers understand the role of NAT and offer a new potentially beneficial treatment approach. Thus, the aim of this systematic review and meta-analysis is to evaluate the role of NAT in prolonging overall survival and disease-free survival and improving R0 and N0 rates compared with upfront resection in patients with resectable pancreatic cancer. ABSTRACT: Background: Despite advances in treatment, the prognosis of resectable pancreatic adenocarcinoma remains poor. Neoadjuvant therapy (NAT) has gained great interest in hopes of improving survival. However, the results of available studies based on different treatment approaches, such as chemotherapy and chemoradiotherapy, showed contrasting results. The aim of this systematic review and meta-analysis is to clarify the benefit of NAT compared to upfront surgery (US) in primarily resectable pancreatic adenocarcinoma. Methods: A PRISMA literature review identified 139 studies, of which 15 were finally included in the systematic review and meta-analysis. All data from eligible articles was summarized in a systematic summary and then used for the meta-analysis. Specifically, we used HR for OS and DFS and risk estimates (odds ratios) for the R0 resection rate and the N+ rate. The risk of bias was correctly assessed according to the nature of the studies included. Results: From the pooled HRs, OS for NAT patients was better, with an HR for death of 0.80 (95% CI: 0.72–0.90) at a significance level of less than 1%. In the sub-group analysis, no difference was found between patients treated with chemoradiotherapy or chemotherapy exclusively. The meta-analysis of seven studies that reported DFS for NAT resulted in a pooled HR for progression of 0.66 (95% CI: 0.56–0.79) with a significance level of less than 1%. A significantly lower risk of positive lymph nodes (OR: 0.45; 95% CI: 0.32–0.63) and an improved R0 resection rate (OR: 1.70; 95% CI: 1.23–2.36) were also found in patients treated with NAT, despite high heterogeneity. Conclusions: NAT is associated with improved survival for patients with resectable pancreatic adenocarcinoma; however, the optimal treatment strategy has yet to be defined, and further studies are required.