Surgical Treatment of Synchronous Liver-only Oligometastatic Pancreatic Adenocarcinoma: a Systematic Review and Meta-analysis of Long-term Outcomes

Background: The potential long-term survival benefits of surgical resection for synchronous liver-only metastases of pancreatic ductal adenocarcinoma (liver oligo-PDAC) remain controversial. This systematic review and meta-analysis aim to compare the current evidence on long-term survival outcomes between surgical treatment of liver oligo-PDAC and conventional systemic chemotherapy. Materials and methods: A systematic review and meta-analysis were conducted using the PubMed and Scopus databases to identify studies comparing surgery and systemic chemotherapy in terms of long-term survival in oligo-PDAC patients. The search included studies published up to October 2024. The meta-analysis was performed using the Jamovi software. Results: Eleven retrospective studies were selected for a total of 897 patients: 565(63%) underwent synchronous resection of liver metastases and the primary tumor, while 332(37%) received conventional chemotherapy. The majority of patients presented a pancreatic head tumor, and the median number of liver metastases ranged between 1 and 3 in the surgical cohort and 1 and 2 in the non-surgical cohort. The rate of major surgical complications was 14.4% while the cumulative incidence of post-operative mortality was 2.8%. The median overall survival(OS) in the surgical group ranged from 7.6 to 18.4 months, while a lower value comprised between 6 and 9.9 months was evidenced in the non-surgical cohort. Six studies were included in the meta-analysis for the OS evaluation, showing significantly better survival outcomes in the surgical group (OR: 0.286, 95% CI: 0.100-0.409; p <0.0001). According to the Q-test, there was no significant heterogeneity in the true outcomes (Q = 4.063, p = 0.541, I2 = 0 %). A sensitivity analysis, conducted by excluding one study at a time, confirmed the robustness of the meta-analysis findings. Conclusions: Surgical resection of oligo-PDAC may represent a valuable treatment option with potential long-term survival benefits. However, prospective randomized trials are required to further validate these findings.