New Research Finds Links between Parkinson’s Disease and 16 Types of Cancer

A startling new study has found correlations between Parkinson's disease and sixteen types of cancer among East Asian populations, findings that contradict previous studies done on Western populations, which showed a decreased risk of cancer for those suffering from this common neurological disease.

In the past 50 years, over 25 epidemiological studies conducted on Western populations have shown a decreased risk in cancer among those with Parkinson's disease compared to those without. The new research may shed more light on the important role genetic backgrounds play in disease development.

The study is the first of its kind conducted on over 62,000 newly diagnosed Taiwanese patients with Parkinson's disease (PD) from 2004 through 2010, as listed in the Taiwan National Health Insurance Research Database. Over 120,000 control participants were also included in the study, which appeared this week in the journal JAMA Oncology.

Pan-Chyr Yang, physician and researcher at the National Taiwan University College of Medicine in Taipei, and coauthors found that while patients with PD appeared not to be associated with increased risk of breast, ovarian or thyroid cancers, there were associations (as measured by increased hazard ratios) with sixteen other types of cancer, among them malignant brain tumors, gastrointestinal tracts cancers, lung cancers, some hormone-related cancers, urinary tract cancers, lymphoma/leukemia, melanoma and other skin cancers.

The new research not only focuses on a population that has been excluded from previous PD research, but also may provide insight into environmental factors that increase risk for disease.

"Further studies are needed to clarify whether our findings can be applied to other East Asian populations," the authors said in a press release. "The striking differences between our study and the previous studies in Western cohorts suggest the importance of ethnicity and environmental exposures in disease pathogenesis."

The authors noted the limitations of the research, "including possible underestimation of PD incidence, smoking status not included in their analysis, speculation about pesticide exposure, and remaining questions regarding genetic correlations."

Parkinson's disease is a progressive neurological disorder that develops gradually, sometimes beginning with a slight tremor in the hand. The condition causes stiffness and slowing of movement, along with slurred speech. And although there is no cure, medications can markedly improve many symptoms.

According to the Parkinson's Disease Foundation, the drug levodopa, which became the mainstay of PD therapy some 40 years ago, has improved life expectancy for patients suffering from this chronic disease. A 2009 report found people with PD had the same life expectancy as those without PD, living to an average age of 77, although those diagnosed later in life and those with severe movement symptoms tend to fall short of this average.

In the United States there are over 50,000 new cases of PD reported each year, adding to the over one million individuals already suffering.