Metformin use and pancreatic ductal adenocarcinoma outcomes: a narrative review.

[BACKGROUND] Metformin is a diabetes medication with anti-mitotic properties. A narrative review was performed to investigate people using metformin and the risk of developing pancreatic ductal adenocarcinoma (PDAC) as well as survival outcomes in established PDAC.

[METHODS] Relevant studies on metformin use and PDAC were retrieved from PubMed including observational studies on metformin and the risk of developing PDAC and survival outcomes in PDAC, and randomized controlled trials of metformin as a treatment in PDAC.

[RESULTS] Of the 367 studies searched, 26 studies fulfilled the criteria for this review. Metformin was not consistently associated with a reduced risk of developing PDAC. However, metformin use, especially higher cumulative doses, in some studies was associated with longer survival in patients with established PDAC, especially in the subgroup with resectable PDAC. Metformin use was not associated with longer survival in more advanced (non-resectable metastatic) PDAC.

[CONCLUSION] Metformin was not consistently associated with a reduced risk of developing PDAC. Metformin may be associated with overall survival benefits in patients with PDAC including the resectable PDAC subgroup but not in the metastatic PDAC subgroup. The evidence to date does not support the routine use of metformin as an adjuvant therapy for advanced PDAC.