Global Association of Cause-specific Mortality between the Major Gastrointestinal Cancers and Parkinson's Disease for the First Two Decades of the New Millennium

Parkinson's disease (PD) and gastrointestinal (GI) cancers are both "age-related diseases" sharing several environmental risk factors, but possess opposite underlying biological mechanisms. Aim of this study was to evaluate the correlations between GI cancers and PD using national cause-specific mortality data of 183 countries extracted from the Global Health Observatory database. The association between PD- and GI cancers- (i.e. esophagus cancer, EC; stomach cancer, SC; colorectal cancer, CRC; liver cancer, LC and pancreatic cancer, PC) specific mortality on the country level was evaluated using Spearman correlation and logistic regression analysis. A global increase in mortality from 2000 to 2019 was observed in PD, CRC and PC, whereas in EC, SC and LC it decreased. We see the consistent diminishment of correlation intensities between PD and GI cancer mortalities from 2000 to 2019 as a positive development. In 2019, PD inversely correlated with CRC (r(s) = -0.39) and PC (r(s) = -0.40, all P < 0.001) but not with EC and SC. Of note, an exceptionally positive correlation of PD with LC (r(s) = 0.26, P < 0.001) and its two hepatitis B and C virus-associated subtypes was revealed. Logistic regression analysis further determined that PD associated negatively with CRC (OR = 0.25) and PC (OR = 0.21, both P < 0.001), but positively with LC (OR = 2.27, P= 0.007). Consequently, future research aiming to unravel the functional biological link between neurodegeneration, hepatitis and tumor development holds great potential for developing novel therapeutics.