Low cancer rates among patients with Parkinson's disease

Abstract

Among 406 patients with Parkinson's disease, the cancer rate (all sites combined) was bout one-third that for the general population. The risk of cancer increased during the treatment period but remained significantly low. Malignant and benign thyroid neoplasms were significantly more frequent than expected among patients with Parkinson's disease. We suggest that high levels of total body potassium in patients with Parkinson's disease is the protective factor against cancer.

Epidemiology and etiology of Parkinson’s disease: a review of the evidence

“…The first study found a lower than expected prevalence of cancer both before and after PD onset (RR 0.43, p<0.00005) [596]. PD cases who smoked had a slightly higher observed versus expected cancer frequency than non-smoking PD cases, but the inverse association with PD remained (RR 0.64, p=0.16), suggesting that reduced smoking did not completely explain the lower cancer risk among PD cases.…”

“…Although overall cancer risk among PD cases was lower in several studies, a relatively consistent finding was increased risk of melanoma [596,597,604,605,608]. In some studies, higher frequency of non-melanoma skin cancer [603,604] and breast cancer [600,604,605] was also reported.…”

“…Two studies from the 1980s used medical records to obtain cancer diagnoses and provided results separately for cancer occurring before and after onset of PD [409,596]. The first study found a lower than expected prevalence of cancer both before and after PD onset (RR 0.43, p<0.00005) [596].…”

A Prospective Cohort Study of Cancer Incidence Following the Diagnosis of Parkinson's Disease

“…The majority of studies that have examined the relationship between Parkinson's disease (PD) and cancer suggest that patients with PD are at decreased risk of smoking-related and most non -smoking-related malignancies (1)(2)(3)(4)(5)(6)(7). A number of hypotheses have been invoked to explain this association.…”

“…Of the few cohort studies (2, 3, 5-7) that have examined the incidence of cancer in patients with PD, most have had retrospective data collection (2,5,6). The large, populationbased databases that have had the power to show a significantly decreased risk of overall cancer in PD have had no ability to adjust for important confounders such as smoking.…”