Effects of Parkinson disease on survival in cancer survivors: a retrospective, multicenter cohort study in Japan

Aging populations and advances in medical care have contributed to an increase in the number of patients with Parkinson disease (PD) and cancer survivors. However, the effects of PD on the survival of patients with cancer remains unclear. We aimed to investigate the effect of PD on the prognosis of patients with cancer. This retrospective multicenter cohort study used data from the Osaka Cancer Registry, which was linked to administrative data obtained between 2010 and 2015 in Japan. Patients with cancer who were followed up for 5 years after cancer diagnosis were categorized into PD and non-PD groups according to the presence of comorbid PD. We compared survival between the two groups using Kaplan–Meier analyses. Cox proportional-hazard models were used to assess the hazard ratio (HR) and 95% confidence interval (CI) of PD for all-cause mortality. Propensity-score matching was used to validate the analysis and address differences in clinical characteristics between the groups. The cohort included 118,999 patients with cancer and 1,049 patients (0.9%) with comorbid PD. The patients in the PD group were older and had lower mobility than those in the non-PD group. Kaplan–Meier analysis revealed that the 5-year survival rate after cancer diagnosis was significantly worse in the PD group than in the non-PD group (54% vs. 70%, P < 0.001). Comorbid PD was independently associated with 5-year mortality (crude HR [95% CI], 1.72 [1.56–1.88], P < 0.001). This association remained significant after adjusting for potential confounders (adjusted HR [95% CI], 1.37 [1.25–1.51], P < 0.001). When the survival analysis was stratified by mobility, no intergroup difference in prognosis was observed among patients with impaired mobility. However, among patients with independent mobility, patients in the PD group had a worse prognosis than those in the non-PD group (crude HR [95% CI], 1.74 [1.42–2.13], P < 0.001). Similar results were observed after propensity-score matching. Patients with cancer and comorbid PD had a worse prognosis than those without comorbid PD. The effect varied depending on mobility. These findings highlight the importance of carefully managing PD symptoms and maintaining mobility in cancer patients with PD, as this could potentially improve their prognosis and survival outcomes.