Incidence and Mortality Rates of Second Pancreatic Cancer among Survivors of Digestive Cancers: A Nationwide Population-Based Study

Objectives We analyzed the incidence and mortality rates of second pancreatic ductal adenocarcinoma (PDAC) among survivors of digestive cancers in South Korea. Methods We evaluated data from the Korea National Health Insurance to identify individuals with digestive cancers in 2005 to 2015. The standardized incidence ratios (SIRs) of second PDACs and survival rates were evaluated. Results Among 772,534 patients with first digestive cancers, 1696 (0.22%) developed second PDACs. The incidence of second PDACs increased until 10 years since the first cancer diagnosis. Patients with biliary tract cancers (BTCs) showed a higher incidence of second PDACs than did those with gastrointestinal cancers or hepatocellular carcinoma. In ages 20 to 49 years, SIRs (95% confidence interval) were higher in survivors of hepatocellular carcinoma (3.08; 1.04-3.08), gastric cancer (3.40; 1.90-3.40), colorectal cancer (5.00; 2.75-5.00), gallbladder cancer (58.52; 11.81-58.52), intrahepatic cholangiocarcinoma (86.99; 1.73-86.99), extrahepatic cholangiocarcinoma (89.41; 27.42-89.41), and ampulla of Vater cancer (156.78; 48.08-156.78). In ages 50 to 64 years, colorectal cancer (1.42; 1.04-1.42), gastric cancer (1.66; 1.29-1.66), and BTCs revealed higher SIRs. In ages more than 65 years, SIR was increased only in BTCs. Second PDACs revealed a more favorable prognosis than first PDACs. Conclusions Careful surveillance for second PDACs after curative treatment of BTCs and colorectal cancers should be considered.