Parkinson’s Disease And Melanoma Risk - The Unsolved Riddle

Highlights:

• Parkinson's disease (PD) is a neurodegenerative disorder and found to be associated with an increased risk of skin cancer and vice versa.
• Patients with Parkinson's disease must be kept under regular review and be counseled about increased risk of skin cancer

Patients with Parkinson's disease have been found to be at an increased risk of melanoma and should be monitored frequently for early signs of cancer. However, more studies are needed to establish the reasons for the possible association in order to refine patient screening criteria and to better advise patients about the risk. The results have been brought out in Mayo Clinic Proceedings.

Parkinson's Disease And Melanoma Risk - Finding Answers

Several earlier studies have shown a link between Parkinson's disease and melanoma, a type of skin cancer originating in the pigment producing melanocytes. The exact reason remains a mystery although some scientists have suggested that levodopa, a drug used in the treatment of Parkinsonism may be the cause, while others have refuted the suggestion.

The current research team embarked on this study to determine if they could validate the findings of previous studies and get more answers to the puzzle.

Parkinson's Disease And Melanoma Risk - The Study

Using the Rochester Epidemiology Project medical records database, the Mayo study team identified all neurologist-confirmed Parkinson's cases over a 37 year period from January 1976 through December 2013 among Olmsted County, Minn., residents.

• The team analyzed the prevalence of melanoma in the 974 Parkinson's disease patients in comparison to 2,922 residents without Parkinson's.
• Similarly, they also identified 1,544 cases of melanoma over the same period and arrived at the 35-year risk of Parkinson's disease in these patients compared with the risk in a similar number of people without melanoma.
• The findings support an association between Parkinson's disease and melanoma, but levodopa is unlikely to be the reason, according to the research team.
• The study found that Parkinson's disease patients were four times more likely to develop melanoma, and patients diagnosed with melanoma were four times more likely to get Parkinson's disease.
• The team believe that other causes such as common genetic factors, immune system abnormalities or environmental influences may be at play but further research is essential to identify and clearly establish the cause.

"Future research should focus on identifying common genes, immune responses and environmental exposures that may link these two diseases," says first author Lauren Dalvin, M.D., a Mayo Foundation Scholar in Ocular Oncology. "If we can pinpoint the cause of the association between Parkinson's disease and melanoma, we will be better able to counsel patients and families about their risk of developing one disease in the setting of the other."

• However, until an answer is found, it is essential for doctors to counsel patients about the associations between the two diseases, as well as patients suffering from either disease to be watchful for warning symptoms and signs and seek prompt medical advice as appropriate.

What Earlier Studies Say About Parkinson's Disease And Melanoma Association

• Previous research suggest that the pigment melanin could be a possible link. Studies have shown that melanin in skin protects against development of melanoma. Interestingly, decreased levels of melanin in the substantia nigra area of the brain is associated with increased susceptibility of these neurons to injury and death resulting in impaired motor functions and PD
• A possible molecular basis has also been put forth. Alterations in GSTM1, CYP2D6 and VDR genes could up the risk for both PD and melanoma. Additionally, some PD-related genes, such as alpha-synuclein, Parkin, LRRK2 and DJ-1, were also found to be key in the pathogenesis of melanoma. However, more studies are needed to validate these observations.
• Defective autophagy mechanisms have been implicated in the development of both PD as well as melanoma. Again more studies are needed to establish these theories.

How To Protect Against Skin cancer?

In addition to Parkinson's disease, several other factors have been known to increase the risk of melanoma. A knowledge of the risk factors can help in taking necessary precautions wherever possible. The risk factors include the following:

• Caucasian race
• Male gender
• Increasing age
• Ultraviolet light exposure (can be reduced or prevented by appropriate precautions such as using suntan lotions, wearing protective clothing and using goggles)
• Family history of skin cancer
• Prior history of melanoma or other skin cancers

In conclusion, more research is indicated to shed light on yet unanswered questions and gain more insight into the pathogenesis of these conditions. However, it goes without saying that persons with known risk factors for skin cancer should have regular followups with a dermatologist and remain aware of the warning signs of melanoma.

References:

1. Parkinson's Disease and Melanoma - (https://www.michaeljfox.org/foundation/news-detail.php?ask-the-md-parkinson-disease-and-melanoma)
2. The association between Parkinson's disease and melanoma: a systematic review and meta-analysis - (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4631109/)

Source-Medindia