Mortality due to amyotrophic lateral sclerosis and Parkinson's disease among melanoma patients.

Recent studies in the USA and elsewhere have identified a possible association between Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and melanoma. However, empirical evidence is very limited. We conducted a study of all people diagnosed as having melanoma in Australia since 1982 (n = 127,037). The subjects, excluding those who had died within 12 months of diagnosis, were followed until 31 December 2001. We then compared their mortality risk of ALS and PD to that of the general population. There were a total of 53 ALS deaths and 129 deaths due to PD. Although the absolute risk is small, the melanoma cohort had a risk of death due to ALS 70% higher (standardised mortality ratio = 169.4, 95% CI = 127-221) than the general population, and nearly a 3-fold increased risk of dying from PD (standardised mortality ratio = 266.3, 95% CI = 222-317). These increased risks continued for long-term survivors, arguing against a surveillance effect (particularly for ALS). The consistency of these results in 2 separate populations (Australia and USA) strengthens the evidence for an association between melanoma and each of the 2 neurodegenerative diseases.