Cholangiocarcinoma (CCA) characterized by late diagnosis and poor outcomes represents the commonest malignancy of biliary tract. Understanding metachronous cancer associations may achieve earlier detection. We aimed to evaluate the risk of subsequent CCAs among common cancer survivors. The National Cancer Institute's Surveillance, Epidemiology, and End Results database (1973-2010) was reviewed for patients with 1 of the 25 primary cancers. Standardized incidence ratios (SIRs) were calculated as an approximation of relative risk for subsequent CCAs after primary malignancy. Data were stratified by age at primary cancer diagnosis, latency period, and application of radiation. A total of 1487 patients developed subsequent CCAs. For patients diagnosed with primary cancers between the ages 20 and 39 years, the risk was increased among colon (SIR 14.65), gallbladder (129.29), and uterus (7.29) cancer survivors. At ages of 40 to 59 years, oral cavity and pharynx (1.89), stomach (3.24), colon (1.76), gallbladder (11.78), and lung cancers (1.75) were associated with increased risk. We found persistently elevated SIRs after colon and gallbladder cancer between ages 60 and 79 years. The SIR remained significant among gallbladder cancer survivors diagnosed after 80 years. Gallbladder cancer showed elevated risk at all of the latency periods except first 6 to 11 months. Increased risk of lung cancer (1.66) was detected after 120 months. However, radiation therapy did not contribute to increased risk. This population-based study suggests that several initial cancers are associated with elevated risk of CCA. The increased risk may be due to shared genetic or environmental etiological factors between these malignancies. Lower threshold for CCA surveillance may be warranted in high-risk patients.
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