Abstract
BACKGROUND/OBJECTIVE: Since the 2010s, Japan's national health insurance system has covered key management for chronic pancreatitis (CP), including pancreatic enzyme replacement therapy. These therapies are expected to improve long-term prognosis; however, recent data are lacking. This study aimed to clarify the updated cancer risk and mortality among patients with CP in Japan. METHODS: We conducted a multicenter, retrospective cohort study on 1,110 patients with CP treated at 28 institutions in 2011. Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) were calculated for comorbidities. Factors associated with the development of malignancy and overall survival were analyzed. RESULTS: Patients with CP had an elevated SIR of 1.62 (95% confidence interval [CI], 1.43-1.83) for malignancy, with the highest risk observed for pancreatic cancer (SIR = 6.44 [95% CI, 4.64-8.90]). During follow-up, 143 patients (12.9%) died, most frequently from malignancy (47.5%). The SMR was elevated in all patients with CP (SMR = 1.20 [95% CI, 1.01-1.42]) and in those with alcohol-related CP (SMR = 1.49 [95% CI, 1.23-1.81]) but not in those with alcohol-unrelated CP. Pancreatic cancer was identified as the strongest factor associated with overall survival (hazard ratio, 48.92 in multivariate analysis). Overall survival of the patients with pancreatic cancer was significantly longer in those who underwent regular examinations for CP at least every three months (P = 0.011). CONCLUSIONS: Patients with alcohol-related CP have higher mortality than the general population in Japan. Pancreatic cancer remains a crucial prognostic factor in patients with CP. Regular surveillance for pancreatic cancer is important to improve their prognosis.