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  • Writer's pictureJiaqi Lin

Parkinson’s Disease and Cancer

Parkinson’s disease (PD) is well-known as a neurodegenerative disease that is characterized by tremors, rigidity, and slowness of movement etc (1). It is often caused by unexpected cell death of dopaminergic neurons the substantia nigra, which is part of the basal ganglia (2). Intuitively, it is dramatically different and can even be biochemically opposite to cancer, which is marked by uncontrolled division of genetically damaged cells. However, studies have revealed intriguing correlations between these two diseases.


First, the risk of both PD and cancer tend to increase with age (2). Moreover, PD-related genes also have implications in cancer. For instance, mutations in PARK2 is the most ubiquitous cause familial forms of PD (3). PARK2 has also been identified as a potent tumor suppressor gene and mutations in which would lead to increased risk of cancer (3). Some other Parkinson-linked genes including DJ-1 and LRRK2 could also produce cancerlike effects (3).


There is an inverse association between PD and total cancer, prostate, bladder, and colorectal cancer (1). One explanation for this relationship is smoking, because smoking is associated with reduced risk of PD and increased risk of many types of cancer (1). In addition, PD patients are less likely to be addicted to smoking (1). That being said, the inverse relationship tends to be dependent on more factors other than smoking. For example, Zhang et al. hypothesized that cell proliferation and survival signal molecules like Wnt, P53, and PI3K/AKT, as well as the ubiquitin proteasome pathway of protein degradation might be up-regulated in cancer and down-regulated in PD (2).


However, recent studies have demonstrated an association between PD and increased risks of breast cancer, brain cancer, and melanoma (a type of skin cancer) (1). Also, patients diagnosed with melanoma would have a 37% higher risk of developing PD (2). Several overlapping characteristics of PD and melanoma were pointed out: both diseases are more common in whites and people with fair skin tones and red hair (2). In terms of lifestyle factors, smoking also plays a crucial role as the comparatively low rate of smoking in PD patients is associated with increased risk of melanoma (2).


Despite these hypothesized explanations, the specific mechanism behind the association between PD and cancer, and if the findings were confounded by other factors, remains elusive. Given that some genes affect the risks of both PD and cancer, more research could be done to investigate the potential role of ethnicity in the relationship between the two diseases (4).


In summary, evidence shows that PD is associated with a lower risk of overall cancer but a higher risk of breast cancer, brain cancer, and melanoma. Due to the current lack of research into the reasons behind this relationship, future research should aim to identify relevant factors and understand how they lead to the association via epidemiological, biochemical, and clinical approaches.


References

  1. Lee JYS, Ng JH, Saffari SE, Tan EK. Parkinson's disease and cancer: a systematic review and meta-analysis on the influence of lifestyle habits, genetic variants, and gender. Aging (Albany NY). 2022;14(5):2148-2173. doi:10.18632/aging.203932

  2. Zhang X, Guarin D, Mohammadzadehhonarvar N, Chen X, Gao X. Parkinson's disease and cancer: a systematic review and meta-analysis of over 17 million participants [published correction appears in BMJ Open. 2021 Sep 22;11(9):e046329corr1]. BMJ Open. 2021;11(7):e046329. Published 2021 Jul 2. doi:10.1136/bmjopen-2020-046329

  3. Ken Garber, Parkinson's Disease and Cancer: The Unexplored Connection, JNCI: Journal of the National Cancer Institute, Volume 102, Issue 6, 17 March 2010, Pages 371–374, https://doi.org/10.1093/jnci/djq081

  4. Gilbert DR. Parkinson's disease & risk of cancer. American Parkinson Disease Association. https://www.apdaparkinson.org/article/cancer-and-parkinsons-disease/. Published November 19, 2019. Accessed November 25, 2022.



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