Metformin may improve survival in pancreatic cancer patients, study suggests

Researchers from the Tisch Cancer Institute of the Icahn School of Medicine at Mount Sinai in New York City have found that patients with type 2 diabetes already taking metformin before a diagnosis of pancreatic cancer had better chance of survival than those on other medications.
The study findings, published in the American Journal of Gastroenterology, showed the benefits of metformin use before developing a very aggressive form of pancreatic cancer called pancreatic ductal adenocarcinoma (PDAC).
PDAC is one of the most difficult malignancy of the pancreas to treat as it is typically diagnosed after the disease has already metastasized (replicated elsewhere in the body). Most PDAC patients have a strikingly poor diagnosis with a 5-year survival on average.
Type 2 diabetes is well established as both a risk factor for and a consequence of PDAC. About 80% of pancreatic cancer patients have glucose intolerance. Thus, the research team investigated whether the medication affected the survival of PDAC patients with type 2 diabetes.
Metformin has been shown in previous studies to possibly be protective against various cancers. Given that there is an association between diabetes and pancreatic cancer, the hypothesis tested by scientists is that controlling diabetes through metformin may also have a positive impact on PDAC.
The co-author of the study, Dr. Paolo Boffetta, and his colleagues at Mount Sinai have used the Surveillance, Epidemiology, and End Results registry (SEER)-Medicare linked database to conduct the experiment.
They identified and followed more than 1,900 patients aged 65 years of age or older when diagnosed with PDAC and who had pre-existing diabetes over a five-year period.
Those patients had taken one type of diabetes medication for at least one year before their cancer diagnosis. More than half of them (57.3%) used metformin and the remainder received other diabetes medications.
The results, adjusted for cofounders including the diabetic comorbidity severity index, Charlson score, as well as chronic kidney disease, revealed that patients taking metformin had significantly lower mortality risk regardless of the use of insulin or other diabetes medications.
However, the study did not try to assess whether starting patients on metformin after diagnosis might alter survival, which would have provided more robust evidence of causal benefit.