Study evaluates co-occurrence of cancers in patients with central nervous system disorders

The study evaluated the co-occurrence of cancers in patients with central nervous system (CNS) disorders, including Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), autism spectrum disorders, Down's syndrome (DS), Huntington's disease (HD), multiple sclerosis (MS), Parkinson's disease (PD) and schizophrenia (SCZ).

A comprehensive search in PubMed/MEDLINE, Scopus and ISI Web of Knowledge of the literature published before March 2013 was performed.

Authors identified 51 relevant articles from 2,229 discrete references, 50 of which contained data suitable for quantitative synthesis (577,013 participants).

Accordingly, the presence of CNS disorders was associated with a reduced co-occurrence of cancer (ES = 0.92; 95% confidence interval, CI: 0.87-0.98; I2 = 94.5%).

A consistently lower overall co-occurrence of cancer was detected in patients with neurodegenerative disorders (ES = 0.80; 95% CI: 0.75- 0.86; I2 = 82.8%), and in those with AD (ES = 0.32; 95% CI: 0.22-0.46; I2 = 0.0%), PD (ES = 0.83; 95% CI: 0.76-0.91; I2 = 80.0%), MS (ES = 0.91; 95% CI: 0.87-0.95; I2 = 30.3%) and HD (ES = 0.53; 95% CI: 0.42-0.67; I2 = 56.4%).

Furthermore, patients with DS showed a higher overall co-occurrence of cancer (ES = 1.46; 95% CI: 1.08-1.96; I2 = 87.9%).

On the contrary, no association was observed between cancer and ALS (ES = 0.97; 95% CI: 0.76-1.25; I2 = 0.0%) or SCZ (ES = 0.98; 95% CI: 0.90-1.07; I2 = 96.3%).

Patients with PD, MS and SCZ showed (a) higher co-occurrence of some specific cancers (e.g. PD with melanoma, MS with brain cancers and SCZ with breast cancer), and (b) lower co-occurrence of other specific cancers (e.g. lung, prostate and colorectal cancers in PD; lung and prostate cancers in MS; and melanoma and prostate cancer in SCZ).

The authors concluded that increased and decreased co-occurrence of cancer in patients with CNS disorders represents an opportunity to discover biological and non-biological connections between these complex disorders.