Atypical cancer pattern in patients with Parkinson's disease

Abstract

Among 14 088 patients, with a primary diagnosis of Parkinson's disease during the period 1977 -98 identified from the National Register of Patients, 1282 cancers were subsequently recorded in the Danish Cancer Registry, compared with 1464 expected, with a standardised incidence ratio (SIR) of 0.88 (95% confidence interval (CI), 0.8 -0.9). Significantly reduced risks were found for smokingrelated cancers, for example, cancers of the lung (SIR, 0.38), larynx (0.47) and urinary bladder (0.52), although moderate reductions in risk were also seen for several nonsmoking-related cancers. In contrast, increased risks were seen for malignant melanoma (SIR, 1.95; 95% CI, 1.4 -2.6), nonmelanocytic skin cancer (1.25; 1.1 -1.4) and breast cancer (1.24; 1.0 -1.5). The observed cancer pattern supports the hypothesis that constituents of tobacco smoke inhibit or delay the development of Parkinson's disease, but a low smoking prevalence appears to be only part of the explanation for the decreased cancer incidence. The increased relative risks of melanoma and nonmelanoma skin cancer are not likely to be artefactual, but further investigations of potential mechanisms are warranted.

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

“…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.…”

“…In some studies, higher frequency of non-melanoma skin cancer [603,604] and breast cancer [600,604,605] was also reported. Based on experimental evidence, a potential link between PD and melanin was suggested in the 1980s [609].…”

“…This association largely was due to an increased risk of non-melanoma skin cancer, suggesting that more intensive surveillance may have played a role [603]. A Danish study based on national hospital discharge and cancer registers (including more than 14,000 PD cases) reported lower risk of cancer after onset of PD (SIR 0.9, 95% CI 0.8-0.9 for overall cancer; SIR 0.6, 95% CI 0.5-0.6 for smoking-related cancer), an association that was largely restricted to men [604]. For cancer occurring before PD [608].…”

Tumorigenesis and neurodegeneration: two sides of the same coin?

“…Interestingly, large cohorts of patients with PD show a slight but statistically significant and reproducible excess risk of specific cancers, particularly breast cancer (standardized incidence ratio 1.24, 95% CI ¼ 1.0-1.5), (70,71) an observation that may be partly explained by parkin deficiency in a subset of patients. The reduced expression of another PD-associated gene, pink1, in certain cancers and its possible regulation by the tumor suppressor gene PTEN (72,73) suggests that the dual roles of tumor suppression and neuroprotection may extend to other PD-associated genes.…”

Current Status of Symptomatic Medical Therapy in Parkinson’s Disease

“…However, two studies have recently demonstrated a small but significant increased relative risk for malignant melanoma and other nonmelanotic skin cancers in PD, but probably not related to LD. 26,27 It is recommended that PD patients be monitored regularly for skin cancer, but a history of melanoma should not preclude the use of LD.…”