By Peter Dull, RN

peter dull
ONS member Peter Dull, RN, is a clinical nurse in the bone marrow and stem cell transplantation program at Mount Sinai Hospital in New York, NY.

Metformin is one of the oldest and most reliable pharmacologic treatments for type-2 diabetes and had, in the past, been suggested as a potential pancreatic cancer risk reducer in the National Comprehensive Cancer Network (NCCN) guidelines for pancreatic adenocarcinoma. Although more recent versions of the guidelines have removed that language, our team was curious about the possible link between metformin and pancreatic cancer risk. 

Considering the drug’s widespread use among patients with type-2 diabetes, our work focused on the available literature to determine whether the drug affected a patient’s risk for pancreatic cancer. Using several of the largest medical publication databases available, our team conducted a structured literary review to identify the current research.

Within the past 10 years, some epidemiologic studies have shown the potential for pancreatic cancer risk reduction with metformin use. We also found that more recent studies have shifted focus to metformin’s ability to increase survival rates in patient who already have pancreatic cancer. Moreover, researchers have been looking at metformin’s impact on risk reduction for many different cancer types beyond pancreatic disease. Although our search was focused on pancreatic cancer, metformin is currently being studied in a variety of cancer-related uses, including clinical trials assessing the drug’s ability to sensitize tumors to radiation treatments. 

One of the biggest challenges we encountered during our search was a lack of randomized, controlled trials among patients with pancreatic cancer. Considering the disease’s relatively low survival rate, coupled with the lack of information specifically highlighting metformin sepa­rate from all antidiabetic medications, the number of articles we examined was limited. A clear gap in available evidence exists, especially for adding the medication to prevention strategies, because of the challenges facing pancreatic cancer survival. 

Ultimately, what the team didn’t find was the most interesting part of our literature review. The evidence was simply not comprehensive enough to support including the drug as a risk reduction strategy in current clinical guidelines. Our team found a total of six applicable articles that met our search criteria containing metformin and pancreatic cancer risk reduction. The findings were split down the middle—three articles supported metformin’s ability to reduce risk and three found insufficient evidence or no discernable change in cancer risk. Based on the current information, our team concluded that the literature did not support the use of metformin as a reliable risk reducing strategy for pancreatic cancer. Its omission from clinical guidelines, including the NCCN’s guidelines for pancreatic adenocarcinoma, is justified. 

Future cancer prevention and risk reduction research should consider how multifactorial cancer disease types are. Our cancer prevention strategies need to be as varied, unique, and individually specific as the diseases that affect our patients.