Tumor diagnosis preceding Parkinson's disease: A case-control study

Lower cancer risk in Parkinson’s disease (PD) patients compared to the general population has been reported. However, most of the studies were based on death certificates. We designed a case– control study to estimate the association of tumor preceding PD onset and PD. PD patients were matched by age and gender to PD-free individuals, randomly selected from the municipalities of residence of cases. Occurrence of tumors preceding PD onset was assessed through a structured questionnaire. Neoplasms were categorized as benign, malignant, or of uncertain classification, and endocrine-related or not. Odds ratios (OR) were calculated using conditional logistic regression and adjusted for tumor categories and risk factors. We included 222 PD patients. Frequency of cancer was 6.8% for cases, 12.6% for controls. PD patients had a decreased risk for neoplasms (adjusted OR, 0.4; 95% confidence interval [CI], 0.2– 0.7). Risk was reduced only for women (adjusted OR, 0.3; 95% CI, 0.1– 0.7). PD patients had a decreased risk both for malignant (adjusted OR, 0.6; 95% CI, 0.1–2.5) and nonmalignant neoplasms (adjusted OR, 0.3; 95% CI, 0.1– 0.7). Still, risk was decreased for endocrine-related tumors (adjusted OR, 0.3; 95% CI, 0.1– 0.9) and non–endocrine-related tumors (adjusted OR, 0.4; 95% CI, 0.1– 0.9). Our study confirms the inverse association between PD and neoplasms reported in previous epidemiologic studies.