By Shreeya Nanda, Senior medwireNews Reporter
A Taiwanese population-based cohort study reports an increased risk of most cancers in patients with Parkinson’s disease (PD), contrasting with findings in Western populations.
Previous studies, mainly conducted in Western populations, have mostly shown that the risk of cancer is lower in patients with than in those without PD, the researchers explain.
“The striking differences between our study and the previous studies in Western cohorts suggest the importance of ethnicity and environmental exposures in disease pathogenesis”, they add in JAMA Oncology.
Using the Taiwan National Health Insurance Research Database, the team identified 62,023 individuals newly diagnosed with PD between 2004 and 2010 and matched them with 124,046 individuals without PD.
PD patients were significantly more likely to develop 16 of the 19 cancers studied compared with non-PD patients, with hazard ratios (HRs) ranging from 3.42 and 2.75 for brain cancer and melanoma, respectively, to 1.47 and 1.36 for colorectal and cervical cancer, respectively.
Breast, ovarian and thyroid cancers were the only malignancies not significantly associated with the neurodegenerative condition.
Further analysis showed that age played a role in modifying the risk of certain cancers. Although the risk of liver cancer was significantly higher in PD patients than non-PD patients in all patients older than 50 years, the risk was highest among those aged between 50 and 59 years, with an HR of 2.57.
And a diagnosis of PD was significantly associated with an increased risk of malignant brain tumours and lung cancers only in patients aged 70 years or older and those aged 60 years or older, respectively.
But PD remained a nonsignificant risk factor for breast, ovarian and thyroid cancers even after the cohort was stratified by age.
“[T]his is the first nationwide large-scale study that has investigated the association between PD and cancers in East Asians”, say Pan-Chyr Yang, from National Taiwan University College of Medicine in Taipei, and colleagues, but they highlight the lack of information on smoking status and pesticide exposure as limiting factors.
Commentators Mary Ganguli and Michael Lotze, both from the University of Pittsburgh School of Medicine in Pennsylvania, USA, note in a linked piece that this study cannot answer the question of whether “PD increases cancer directly, or whether they share common antecedents or mechanisms”.
But they add: “Having now established that these complex diseases (PD and cancer) are linked, the way seems clear for careful and systematic analysis of both the intrinsic differences in cell biology as well as extrinsic factors found in the environment that link them.”
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