Chronic Pancreatitis and Pancreatic Cancer Risk: A Systematic Review and Meta-analysis.

Chronic pancreatitis is a putative risk factor for pancreatic cancer. The aim of this study was to examine the magnitude and temporality of this association. We searched MEDLINE and EMBASE for observational studies investigating the association between chronic pancreatitis and pancreatic cancer. We computed overall effect estimates (EEs) with associated 95% confidence intervals (CIs) using a random-effects meta-analytic model. The EEs were stratified by length of follow-up from chronic pancreatitis diagnosis to pancreatic cancer (lag period). Robustness of the results was examined in sensitivity analyses. We identified 13 eligible studies. Pooled EEs for pancreatic cancer in patients with chronic pancreatitis were 16.16 (95% CI: 12.59-20.73) for patients diagnosed with pancreatic cancer within 2 years from their chronic pancreatitis diagnosis. The risk of pancreatic cancer in patients with chronic pancreatitis decreased when the lag period was increased to 5 years (EE: 7.90; 95% CI: 4.26-14.66) or a minimum of 9 years (EE: 3.53; 95% CI: 1.69-7.38). In conclusion, chronic pancreatitis increases the risk of pancreatic cancer, but the association diminishes with long-term follow-up. Five years after diagnosis, chronic pancreatitis patients have a nearly eight-fold increased risk of pancreatic cancer. We suggest that common practice on inducing a 2-year lag period in these studies may not be sufficient. We also recommend a close follow-up in the first years following a diagnosis of chronic pancreatitis to avoid overlooking a pancreatic cancer.