Researchers believe they have found evidence linking Parkinson’s disease with an increased risk of prostate cancer and melanoma. The association may also include an increased cancer risk among close and distant relatives of individuals with Parkinson’s disease (PD).
University of Utah researchers say that this is the first time that an increased risk of prostate cancer has been reported in Parkinson’s disease (although a link with melanoma has been suspected).
Historically, studies have suggested individuals with PD have an overall decreased rate of cancer, with the notable exception of melanoma, the most serious form of skin cancer.
This relationship was found in first-degree relatives with a shared environment, thereby limiting investigations on whether a genetic or common environment background contributed to the PD/melanoma link.
Now researchers are taking a different view.
“Neurodegenerative disorders such as Parkinson’s disease may share common disease-causing mechanisms with some cancers,” says Stefan-M. Pulst, M.D., professor and chair of the department of neurology, at the University of Utah, and co-author on this study.
“Using the Utah Population Database, we were able to explore the association of PD with different types of cancer by studying cancer risk in individuals with PD, as well as their close and distant relatives.”
Researchers identified nearly 3,000 individuals with at least three generations of genealogical data who had PD listed as their cause of death.
The investigators discovered that the risk of prostate cancer and melanoma within this PD population was significantly higher than expected. They also observed an increased risk for prostate cancer and melanoma among first-, second-, and third-degree relatives of these individuals with PD, although the excess risk for melanoma in third-degree relatives did not reach statistical significance.
“In our study, we not only identified an increased risk for prostate cancer and melanoma among individuals with PD and their relatives, but also established a reciprocal risk for PD among individuals with these two cancers and their relatives,” said Pulst.
“Collectively, these data strongly support a genetic association between PD and both prostate cancer and melanoma.”
However, for some conditions, environmental factors also are believed to play a role in disease development. For example, individuals with PD demonstrated a decreased risk for lung cancer, a finding that did not extend to any of their relatives. This suggests that environmental, rather than genetic, factors might be responsible for this association.
“Our findings point to the existence of underlying pathophysiologic changes that are common to PD, prostate cancer, and melanoma,” said the researchers. “Exploring the precise genetic links among these diseases could improve our understanding of PD and influence strategies for prostate and skin cancer screening.”