Inverse relationship between Parkinson’s disease and cancer in Korea: a longitudinal study of a national health screening cohort

Abstract Background: Despite growing epidemiological evidence, the relationship between Parkinson’s disease (PD) and cancer has not been conclusively demonstrated, and related studies are scarce in the Asian population. Objectives: We aimed to determine the association between PD and subsequent development of various cancers from longitudinal data of a representative sample of Korean adults aged ≥40 years. Methods: We retrospectively identified 8,381 patients diagnosed with PD from 2002 to 2019 using claims data among 514,866 people of random samples from the Korean National Health Insurance database. We sampled 33,524 age-, sex-, income-, and residential area-matched participants without PD from the same database. The longitudinal associations between PD and overall cancers, as well as 10 common types of cancer, were estimated using multivariable Cox proportional-hazards regression analysis. Results: The adjusted hazard ratio (aHR) of all cancer types was 0.63 (95% confidence interval = 0.57-0.69) in patients with PD compared with matched controls. The aHRs of gastric, thyroid, colorectal, lung, hepatic, and pancreatic cancer and hematological malignancy was 0.69 (0.56-0.85), 0.60 (0.39-0.93), 0.56 (0.44-0.70), 0.71 (0.58-0.84), 0.64 (0.48-0.86), 0.37 (0.23-0.60), and 0.56 (0.36-0.87), respectively. The associations of bladder, gallbladder and biliary duct, and kidney cancer with PD were not statistically significant. Conclusions: Our findings show that the inverse association with overall cancer and most cancer types in patients with PD. These inverse associations and their pathogeneses merits further investigation.