Oligometastatic Pancreatic Cancer to the Liver in the Era of Neoadjuvant Chemotherapy: Which Role for Conversion Surgery? A Systematic Review and Meta-Analysis

SIMPLE SUMMARY: The development of new polychemotherapy regimens in patients with metastatic pancreatic cancer (mPDAC) have demonstrated significant improvement in clinical outcome, but evidence of the role of surgery following a favorable response to initial chemotherapy (IC) is still poor. The aim of the study is to analyze the impact of surgery following IC on survival in mPDAC, focusing on oligometastatic disease to the liver. Data retrieved from available literature confirm increased survival in selected oligometastatic patients treated with surgery + IC compared to IC alone (23–56 months vs. 11–16.4 months), suggesting a potential role for conversion surgery in a tailored and multimodality approach to pancreatic cancer patients. Better knowledge of tumor biology and a wide consensus on diagnostic criteria could lead to the consideration of oligometastatic disease as a particular and different stage of disease. ABSTRACT: Background: the improved survival rates achieved using new polychemotherapy regimens in patients with metastatic pancreatic cancer (mPDAC) have suggested a potential role for surgery following a favorable response to initial chemotherapy (IC). The purpose of this systematic review is to summarize the available evidence on the role of surgery following IC in mPDAC, focusing on oligometastatic disease to the liver (lmPDAC). Methods: studies reporting on patients with lmPDAC undergoing surgery after IC were included. The main outcome was overall survival (OS). Results: six observational retrospective studies were included in the qualitative analysis. Data were retrieved on 2087 patients. The most common IC regimen in patients undergoing surgery was FOLFIRINOX (N 84, 73%). Only three studies reported survival comparison among patients treated with IC+surgery vs. IC alone. Median OS varied from 23 to 56 months after conversion surgery vs. 11 to 16.4 months after IC alone. Conclusions: despite wide heterogeneity of chemotherapy regimens, different downstaging criteria and potential selection biases, patients with oligometastatic lmPDAC undergoing surgery after IC have significantly higher survival rates compared to patients treated with IC alone. Future trials are needed for definition of univocal criteria of downstaging, oligometastatic definition and indications for surgery.