Parkinson's disease (PD) has been found to be associated with 16 types of cancer in a study in Taiwan.
It was an effort to explain the association in an East Asian population because most prior research has been conducted in Western populations.
Researchers used Taiwan National Health Insurance Research Database to build a final study group of 62,023 patients newly diagnosed with PD from 2004 through 2010 and 124,046 control participants without PD.
"Based on this nationwide study on the association between PD (Parkinson disease) and cancer risk, we conclude that PD is a risk factor for most cancer in Taiwan," said Pan-Chyr Yang of the National Taiwan University College of Medicine, Taipei.
A PD diagnosis was not associated with increased risk of breast, ovarian or thyroid cancers.
In the study, only breast, ovarian and thyroid cancers were found not to be associated with PD.
But, PD appeared associated (as measured by increased hazard ratios) with 16 other cancers including malignant brain tumours, gastrointestinal tracts cancers, lung cancers, some hormone-related cancers, urinary tract cancers, lymphoma/leukemia, melanoma and other skin cancers.
Further studies are needed to clarify whether our findings can be applied to other East Asian populations.
"The striking differences between our study and the previous studies in Western cohorts suggest the importance of ethnicity and environmental exposures in disease pathogenesis," Yang concluded.
The study appeared online in the journal JAMA Oncology.