BACKGROUND : Among patients with pancreatic cancer, the association of pre-existing mental illness with long-term outcomes remains unknown.

METHODS : Individuals diagnosed with pancreatic adenocarcinoma were identified in the SEER-Medicare database. Patients were classified as having mental illness if an ICD9/10CM code for anxiety, depression, bipolar disorder, schizophrenia or other psychotic disorder was recorded.

RESULTS : Among the 54,234 Medicare beneficiaries with pancreatic cancer, roughly 1 in 12 (n = 4793, 8.83%) individuals had a diagnosis of a mental illness. The majority (n = 4029, 84.1%) had anxiety or depression, while 16% (n = 764) had bipolar/schizophrenic disorders. On multivariable analysis, among patients with early stage cancer, individuals with pre-existing anxiety/depression and bipolar/schizophrenic disorders had 22% (OR 0.78, 95% CI 0.69-0.86) and 46% (OR 0.54, 95% CI 0.42-0.70) reduced odds, respectively, to undergo cancer-directed surgery. Furthermore, patients with a pre-existing history of bipolar/schizophrenic disorders had a 20% (HR 1.20, 95% CI 1.21-1.40) higher risk of all-cause mortality and 27% (HR 1.27, 95% CI 1.17-1.37) higher risk of pancreatic cancer-specific mortality compared to individuals without a history of mental illness.

CONCLUSION : One in twelve patients with pancreatic cancer had a pre-existing mental illness. Individuals with mental illness were more likely to have worse overall and cancer-specific long-term outcomes.