FACT: People with Alzheimer’s have a reduced chance of developing all known cancers (Source).
FACT: People with Parkinson’s disease have a reduced chance of developing all known cancers (Source)……except for one.
Melanoma. Source: Wikipedia
It is a curious fact, but people with Parkinson’s disease are 2-8 times more likely to develop melanoma than people without Parkinson’s (Source: Olsen et al, 2005; Olsen et al, 2006; Driver et al 2007; Gao et al 2009; Lo et al 2010; Bertoni et al 2010; Schwid et al 2010; Ferreira et al, 2010; Inzelberg et al, 2011; Liu et al 2011; Kareus et al 2012; Wirdefeldt et al 2014; Catalá-López et al 2014; Constantinescu et al 2014; Ong et al 2014).
PLEASE NOTE: This is NOT to say that people with Parkinson’s disease are going to develop melanoma, it is simply making people with PD (and their carers) more aware that they should be keeping an eye out for it.
And there is another interesting connection between Parkinson’s disease and melanoma – if you have melanoma you are almost 3 times more likely to develop Parkinson’s disease than someone without melanoma (Source: Baade et al 2007; Gao et al 2009).
PLEASE NOTE AGAIN: This is NOT to say that if you have a melanoma you are automatically going to develop Parkinson’s disease. It is just something to be aware of.
So, what’s going on here?
The simple answer is: we don’t know.
A lot of people are now looking at this issue though and we know that the connection is probably NOT genetic: approx. 10% of all cases of Parkinson’s disease can be associated with genetic mutants passed down through families. But none of the known Parkinson’s mutations make you more susceptible to melanoma. Equally, genetic susceptibility has been associated with 4-8% of all melanoma cases, but none of those genetic mutations makes one vulnerable to Parkinson’s disease (Meng et al 2012; Dong et al 2014; Elincx-Benizri et al 2014).
While we’re not sure what is happening between Melanoma and Parkinson’s disease, we are definitely very interested in the connection, and we will be watching this space closely. We’ll be sure to report any new discoveries relating to this in the future.