Analysis of Parkinson's disease and subsequent cancer risk in Taiwan: a nationwide population-based cohort study

Cutaneous malignancies in patients with Parkinson's disease at a dermato-oncological university centre in Hungary

Background

The possible correlation between melanoma and Parkinson's disease (PD) has been intensively studied. In this work, we aimed to assess the coincidence of skin malignancies and PD at a dermato-oncological university centre in Central-Eastern Europe, Hungary.

Methods

From 2004 to 2017, a retrospective analysis of the centre's database was performed based on International Statistical Classification of Diseases-10 codes.

Results

Out of the patients who visited the clinic during the study period, 20,658 were treated for malignant skin tumours. Over the 14 years, 205 dermatological patients had PD simultaneously, 111 (54%) of whom had at least one type of skin malignancy: melanoma (n=22), basal cell carcinoma (BCC) (n=82), or squamous cell carcinoma (SCC) (n=36) (in some patients, multiple skin tumours were identified). Compared to the age- and sex-matched control group, patients with PD had a significantly lower risk for basal cell carcinoma (OR, 0.65; 95% CI, 0.47-0.89, p=0.0076) and for all skin tumours (OR, 0.74; 95% CI, 0.56-0.98, p=0.0392) but not for melanoma.

Conclusions

We found a decreased risk of all skin tumours and basal cell carcinoma and an unchanged risk of melanoma among patients with PD. However, it should be kept in mind that some large-scale meta-analyses suggest a higher incidence of melanoma after a diagnosis of PD, indicating the importance of skin examination in this vulnerable population.

Parkinson's disease and cancer: a systematic review and meta-analysis on the influence of lifestyle habits, genetic variants, and gender

PURPOSE

The relationship between Parkinson's disease (PD) and cancer has been debated. Gender and genetic influences on cancer development in PD is unclear.

METHODS

Using QUOROM guidelines, we conducted a systematic review and meta-analysis on potential clinical and genetic factors influencing the PD and subsequent cancer relationship. English articles published in PubMed, Web of Science, and SCOPUS from 2010 to 30 August 2020 were considered for suitability.

RESULTS

Of 46 studies identified, fourteen satisfied the inclusion criteria and were further analysed. Unadjusted risk ratios (RR) and 95% confidence intervals were computed to determine the PD and cancer relationship. PD patients have decreased subsequent cancer risks (RR = 0.87, 95% CI = 0.81-0.93), reduced risks of colon, rectal, and colorectal cancer (RR = 0.77, 95% CI = 0.63-0.94), lung cancer (RR = 0.62, 95% CI = 0.48-0.80), and increased brain cancer (R = 1.48, 95% CI = 1.02-2.13) and melanoma risk (R = 1.76, 95% CI = 1.23-2.50). Compared to idiopathic PD, LRRK2-G2019S carriers had increased general cancer risks (RR = 1.26, 95% CI = 1.09-1.46), particularly brain (RR = 2.41, 95% CI = 1.06-5.50), breast (RR = 2.57, 95% CI = 1.19-5.58), colon (RR = 1.83, 95% CI = 1.13-2.99), and haematological cancers (RR = 2.05, 95% CI = 1.07-3.92). Female PD patients have decreased general cancer risks compared to male PD patients in this analysis (RR = 0.83, 95% CI = 0.69-0.98).

CONCLUSION

PD patients have reduced risks of colon, rectal, colorectal cancer and lung cancers and increased risks of brain cancer and melanoma. LRRK2-G2019S carriers have increased cancer risks, particularly brain, breast, colon and blood cancers. Female gender was associated with reduced risks. The role of ethnicity, comorbidities, and lifestyle habits on PD patients' subsequent cancer risk should be further investigated.

Cancer in Parkinson’s Disease, a Review of Literature

Background/Aim: The present study aimed to assess the conclusions of literature articles on the matter of cancer in Parkinson’s disease.

Patients and Methods: Studies and articles that contained information on epidemiology, pathophysiological, clinical as well as associations and correlations on the topic of Parkinson’s disease and cancer were incorporated in the research too.

Results: The prevalent part of the investigations and studies on the matter of Parkinson’s disease patients’ risk of cancer revealed a decreased lifetime risk in comparisson with non-PD subjects. In the literature, the most prevalent types of cancer among Parkinson’s disease patients were melanoma and other subtypes skin cancer and also, breast cancer.

Conclusion: Epigenetic factors, gene–environment interactions, and problematic events can have an impact in the occurance and progression of Parkinson’s disease. Further, the mentioned factors can also determine the developing of cancer. Therefore, a complex and interesting relation between the two diseases is further to be discovered.

Patients with Parkinson's disease predict a lower incidence of colorectal cancer

BACKGROUND

Recent theory on the "gut-brain axis" suggests a close relationship between the dysfunction of the gut and the disorders of the brain.

METHODS

We performed a systemic literature search followed by a multi-step inclusion selection for all studies on the risk of Colorectal cancer (CRC) in Parkinson's disease (PD) patients using the following databases: PubMed, EMBASE and WOS. Relative risk (RR) and the 95% confidence intervals (CI) were calculated using either the random-effects model or the fixed-effects meta-analysis model, based on the assessment of heterogeneity.

RESULTS

Seventeen studies involving a total of 375,964 PD patients and 879,307 cancer patients were included. Independent meta-analyses for cohort studies and case-control studies showed that the overall pooled RR of the cohort studies was 0.78 (0.66-0.91), and that of the case-control studies was 0.78 (0.65-0.94), indicating that patients with PD have a significantly decreased risk for CRC. The significant lower risk is present in both the colon and the rectum subgroups classified by tumor location. Moreover, the risk for CRC is significantly lower in America (RR = 0.58), Europe (RR = 0.82) and Asia (RR = 0.83) compared to the control population.

CONCLUSION

The occurrence of CRC was significantly lower in patients with diagnosis of PD.

Cancer risk in Parkinson disease: An updated systematic review and meta-analysis

BACKGROUND AND PURPOSE

Increasing evidence suggests significant associations between Parkinson disease (PD) and cancer risks. We conducted an updated review of studies that examined the risks of various cancer among PD patients and how this differed when cancer preceded PD diagnosis or PD diagnosis preceded cancer.

METHODS

Four databases were searched for studies that examined the association between PD and incidence of cancer from database inception to 4 June 2021. Three independent reviewers screened the articles for eligibility and extracted study data. Pooled relative risk with 95% confidence intervals were calculated using a random effects model.

RESULTS

Forty studies involving 11 case-control studies, two nested case-control studies, 22 cohort studies, and five cross-sectional studies were included. Compared to controls, PD patients had lower risks of lung, genitourinary, gastrointestinal, and haematological cancers. Conversely, higher risks of melanoma and brain cancer were noted among PD patients. No association was found between PD and risk of female cancers. Subgroup analysis found negative associations between PD patients and risks of colon cancer, rectal cancer, and non-Hodgkin lymphoma.

CONCLUSIONS

Findings from our meta-analysis suggest PD patients had lower risks of lung, genitourinary, gastrointestinal, and haematological cancers and increased risks of melanoma and brain cancer. Future research to investigate the underlying mechanisms between PD and cancers is warranted.

Parkinson's disease and cancer: a systematic review and meta-analysis of over 17 million participants

OBJECTIVE

To systematically review and qualitatively evaluate epidemiological evidence on associations between Parkinson's disease (PD) and cancer via meta-analysis.

DATA SOURCES

MEDLINE via PubMed, Web of Science and EMBASE, until March 2021.

STUDY SELECTION

Included were publications that (1) were original epidemiological studies on PD and cancer; (2) reported risk estimates; (3) were in English. Exclusion criteria included: (1) review/comments; (2) biological studies; (3) case report/autopsy studies; (4) irrelevant exposure/outcome; (5) treated cases; (6) no measure of risk estimates; (7) no confidence intervals/exact p values and (8) duplicates.

DATA EXTRACTION AND SYNTHESIS

PRISMA and MOOSE guidelines were followed in data extraction. Two-step screening was performed by two authors blinded to each other. A random-effects model was used to calculate pooled relative risk (RR).

MAIN OUTCOMES AND MEASURES

We included publications that assessed the risk of PD in individuals with vs without cancer and the risk of cancer in individuals with vs without PD.

RESULTS

A total of 63 studies and 17 994 584 participants were included. Meta-analysis generated a pooled RR of 0.82 (n=33; 95% CI 0.76 to 0.88; p<0.001) for association between PD and total cancer, 0.76 (n=21; 95% CI 0.67 to 0.85; p<0.001) for PD and smoking-related cancer and 0.92 (n=19; 95% CI 0.84 to 0.99; p=0.03) for non-smoking-related cancer. PD was associated with an increased risk of melanoma (n=29; pooled RR=1.75; 95% CI 1.43 to 2.14; p<0.001) but not for other skin cancers (n=17; pooled RR=0.90; 95% CI 0.60 to 1.34; p=0.60).

CONCLUSIONS

PD and total cancer were inversely associated. This inverse association persisted for both smoking-related and non-smoking-related cancers. PD was positively associated with melanoma. These results provide evidence for further investigations for possible mechanistic associations between PD and cancer.

PROSPERO REGISTRATION NUMBER

CRD42020162103.

Risk of Nonmelanoma Skin Cancers and Parkinson's Disease-Meta-Analysis and Systematic Review

Simple Summary

Non-melanoma skin cancers (NMSCs) are the most common cancers among fair-skinned people. It is estimated that 2–3 million new cases of NMSCs are diagnosed globally each year. The risk of development increases with age, just like in the case of Parkinson Disease. Due to the general aging of the population and substantially high medical costs of NMSC therapy, NMSCs and Parkinson’s disease (PD) are becoming an increasing health problem. In this paper, we conduct a meta-analysis and systematic review to evaluate the NMSC risk among patients with PD. This study is the first to focus on the effect of different epidemiologic aspects of NMSCs and PD in detail.

Abstract

Patients with Parkinson’s disease (PD) have an increased risk of melanoma compared with the general population. Considering that Nonmelanoma Skin Cancers (NMSCs) share similar risk factors with melanoma, there is a need to understand a possible connection between PD and NMSCs. The aim of the study was the evaluation of NMSC risk among PD patients via meta-analysis and systematic review. A comprehensive search of PubMed, Scopus, and Web of Science databases was conducted, including studies from January 2000 to April 2020. We identified 16 eligible studies including 140291 PD patients. Upon statistical analysis, a significantly higher risk of developing NMSCs in PD patients was found compared with the control group (odds ratio (OR) = 1.25, 95% CI: 1.17–1.33; p < 0.0001). Among all NMSCs, the risk of developing basal cell carcinoma in PD patients was significantly higher (OR = 1.30, 95% confidence interval (CI): 1.15–1.47; p < 0.0001), contrary to squamous cell carcinoma. Further analysis revealed a significantly higher risk of developing NMSCs in patients with previously diagnosed PD (OR = 1.26, 95% CI: 1.19–1.33; p < 0.0001). Our data suggest the necessity for regular skin examination of PD patients, though further studies are required to explore the mechanisms forming this relationship.

The Links between Parkinson's Disease and Cancer

Epidemiologic studies indicate a decreased incidence of most cancer types in Parkinson’s disease (PD) patients. However, some neoplasms are associated with a higher risk of occurrence in PD patients. Both pathologies share some common biological pathways. Although the etiologies of PD and cancer are multifactorial, some factors associated with PD, such as α-synuclein aggregation; mutations of PINK1, PARKIN, and DJ-1; mitochondrial dysfunction; and oxidative stress can also be involved in cancer proliferation or cancer suppression. The main protein associated with PD, i.e., α-synuclein, can be involved in some types of neoplastic formations. On the other hand, however, its downregulation has been found in the other cancers. PINK1 can act as oncogenic or a tumor suppressor. PARKIN dysfunction may lead to some cancers’ growth, and its expression may be associated with some tumors’ suppression. DJ-1 mutation is involved in PD pathogenesis, but its increased expression was found in some neoplasms, such as melanoma or breast, lung, colorectal, uterine, hepatocellular, and nasopharyngeal cancers. Both mitochondrial dysfunction and oxidative stress are involved in PD and cancer development. The aim of this review is to summarize the possible associations between PD and carcinogenesis.

Parkinson's disease and skin cancer risk: a nationwide population-based cohort study in Korea

BACKGROUND

Previous studies have reported that patients with Parkinson's disease (PD) have a significantly lower risk of cancer. Studies reporting prevalence of skin cancers in Parkinson's disease mostly involve Caucasians.

OBJECTIVE

A nationwide population-based study was conducted to determine the risk of skin cancer in patients diagnosed with PD in Korea.

METHODS

Data obtained from National Health Insurance Claims records were used to retrieve information about 70 780 patients with newly diagnosed PD between January 2010 and December 2015. The control group included 353 900 sex- and age-matched patients without PD. In this nationwide population-based cohort study, we investigated the association between PD and skin cancer.

RESULTS

The overall hazard ratio (HR) of skin cancers in patients with PD was 1.169 (95% CI, 1.005-1.359) compared with non-PD group. Among patients with PD, males aged above 65 had a 2.8-fold increase in the risk for melanoma development than the non-PD group (HR, 2.825; 95% CI, 1.395-5.721). In addition, female PD patients aged above 65 years showed a 1.3-fold increase in non-melanoma skin cancer risk than the non-PD group (HR, 1.305; 95% 1.073-1.589).

CONCLUSION

Compared with the general population, Korean patients diagnosed with PD had a greater risk of skin cancer. Especially, male patients aged 65 years and above, and diagnosed with PD had a significant risk of melanoma development compared with control.

Association between Alzheimer's Disease and Cancer Risk in South Korea: an 11-year Nationwide Population-Based Study

Background and Purpose

Previous studies have suggested a decreased cancer risk among patients with Alzheimer's disease (AD). There remains a lack of data on the specific types of cancer and risk factors for developing cancer in AD. We evaluated the association between AD and cancer risk, and we examined specific types of cancer.

Methods

A population-based longitudinal study was conducted using the National Health Insurance Service-Senior cohort for 2002–2013. A total of 4,408 AD patients were included in the study, as were 19,150 matched controls. Potential associations between the risk of cancer and AD were analyzed using Cox proportional hazard regressions.

Results

Cancer developed in 12.3% of the AD group patients and in 18.5% of control group subjects. AD was associated with a reduced risk of cancer (hazard ratio [HR], 0.70; 95% confidence intervals, 0.64–0.78). The risk of head and neck cancers was significantly reduced (HR, 0.49), as were risks for cancers of the digestive tract, including stomach cancer (HR, 0.42), colorectal cancer (HR, 0.61), liver and biliary tract cancers (HR, 0.68), and pancreatic cancer (HR, 0.55). Lung and prostate cancer risks were also significantly lower for the AD group (HR, 0.52 and HR, 0.72, respectively).

Conclusions

Our results showed an inverse association between AD and cancer. Further research involving a large number of patients in a hospital based-study is needed to address the biological associations between cancer development and dementia, including AD.

Association between Parkinson's disease and risk of prostate cancer in different populations: An updated meta-analysis

Recently, growing evidence has revealed a significant association between Parkinson’s disease (PD) and cancer. However, controversy still exists concerning the association between PD and prostate cancer. A comprehensive article search for relevant published studies was performed using the online databases PubMed, Web of Science and Embase up to January 1, 2017. The pooled risk ratios (RRs) and their 95% confidence intervals (CIs) were calculated using the method of inverse variance with a random-effects model. Fifteen studies comprising 346,153 PD patients were included in this study. The results of the present study showed that PD was significantly associated with a decreased risk of prostate cancer in the Western population (RR: 0.83, 95% CI: 0.72–0.95, P < 0.01), while an increased risk of prostate cancer was shown in the Asian population (RR: 1.80, 95% CI: 1.52–2.13, P < 0.001). In the subgroup analysis, the reduced risk of prostate cancer in PD patients from Western populations was consistent regardless of study design or study quality. In conclusion, PD was significantly associated with a reduced risk of prostate cancer in the Western population. The relationship between those conditions in the Asian population needs to be confirmed by future studies.

Carbidopa is an activator of aryl hydrocarbon receptor with potential for cancer therapy

Carbidopa is used with l-DOPA (l-3,4-dihydroxyphenylalanine) to treat Parkinson's disease (PD). PD patients exhibit lower incidence of most cancers including pancreatic cancer, but with the notable exception of melanoma. The decreased cancer incidence is not due to l-DOPA; however, the relevance of Carbidopa to this phenomenon has not been investigated. Here, we tested the hypothesis that Carbidopa, independent of l-DOPA, might elicit an anticancer effect. Carbidopa inhibited pancreatic cancer cell proliferation both in vitro and in vivo. Based on structural similarity with phenylhydrazine, an inhibitor of indoleamine-2,3-dioxygenase-1 (IDO1), we predicted that Carbidopa might also inhibit IDO1, thus providing a molecular basis for its anticancer effect. The inhibitory effect was confirmed using human recombinant IDO1. To demonstrate the inhibition in intact cells, AhR (aryl hydrocarbon receptor) activity was monitored as readout for IDO1-mediated generation of the endogenous AhR agonist kynurenine in pancreatic and liver cancer cells. Surprisingly, Carbidopa did not inhibit but instead potentiated AhR signaling, evident from increased CYP1A1 (cytochrome P450 family 1 subfamily A member 1), CYP1A2, and CYP1B1 expression. In pancreatic and liver cancer cells, Carbidopa promoted AhR nuclear localization. AhR antagonists blocked Carbidopa-dependent activation of AhR signaling. The inhibitory effect on pancreatic cancer cells in vitro and in vivo and the activation of AhR occurred at therapeutic concentrations of Carbidopa. Chromatin immunoprecipitation assay further confirmed that Carbidopa promoted AhR binding to its target gene CYP1A1 leading to its induction. We conclude that Carbidopa is an AhR agonist and suppresses pancreatic cancer. Hence, Carbidopa could potentially be re-purposed to treat pancreatic cancer and possibly other cancers as well.

Increased risk of brain tumor in patients with Parkinson's disease: a nationwide cohort study in Taiwan

OBJECTIVES

Parkinson's disease (PD) is a neurodegenerative disease. A decreased risk of cancer, except for melanoma, has been observed in patients with PD. The aim of this study was to evaluate the association between brain tumor and PD in a Taiwanese population.

MATERIALS AND METHODS

We used data from the National Health Insurance program of Taiwan. The PD cohort contained 2998 patients, and each patient was frequency-matched, based on age and sex, with 4 people without PD, who were randomly selected from the general population. Cox's proportional hazard regression analysis was conducted to estimate the effects of PD on the risk of brain tumor.

RESULTS

The risk of developing brain tumor was significantly higher in patients with PD than in those without PD (adjusted hazard ratio = 2.11; 95% confidence interval (CI) = 1.24-3.59), and benign brain tumor exhibited a particularly elevated risk of 2.16-fold (95% CI = 1.26-3.68). The hazard ratio (HR) for developing a benign brain tumor was higher in female patients with PD than in female patients without PD, with the risk being 2.65-fold (95% CI = 1.30-5.43). An analysis of the two age groups, 50-64 years and ≥65 years, showed that the HR of only the 50-64-year group was significantly higher between the PD and non-PD groups (HR = 2.77, 95% CI = 1.07-7.14).

CONCLUSION

The present study showed that Taiwanese patients with PD are at a higher risk of developing brain tumor than the general population. The exact underlying etiologies require further investigation.

The association between Parkinson's disease and melanoma: a systematic review and meta-analysis

Objective

To assess the association between Parkinson’s disease (PD) and melanoma via systematic review and meta-analysis.

Methods

Comprehensive search in PubMed, Web of Science, Embase and four China databases (SinoMed, WanFang data, CNKI and VIP database) of epidemiologic evidences on PD and melanoma published before April 30, 2015. Studies which reported risk estimates of melanoma among PD patients or risk estimates of PD in patients with melanoma were included. Pooled odds ratios (ORs) with 95 % confidence intervals (CIs) were calculated by random-effects models. Heterogeneity across studies was assessed using Cochran Q and I² statistics. Subgroup analyses and sensitivity analyses were conducted to evaluate sources of heterogeneity. Subgroup analyses were done according to temporal relationship, geographic region and gender respectively. We assessed publication bias using the Begg and Egger test. In addition, study appraisal was done using a scale for observational studies to ensure the quality of evidence.

Results

We identified 24 eligible studies on PD and melanoma with a total number of 292,275 PD patients: the pooled OR was 1.83 (95 % CI 1.46–2.30) overall, subgroup analyses by temporal relationship showed that risk of melanoma after PD diagnosis was significantly higher (OR 2.43, 95 % CI 1.77–3.32), but not before the diagnosis of PD (OR 1.09, 95 % CI 0.78–1.54). Subgroup analysis by geographic region showed that increased risk of melanoma in PD was found both in Europe (OR 1.44, 95 % CI 1.22–1.70) and in North America (OR 2.64, 95 % CI 1.63–4.28). Gender-specific subgroup analyses did not show difference between men (OR 1.64, 95 % CI 1.27–2.13) and women (OR 1.38, 95 % CI 1.04–1.82) in the risk of melanoma. In addition, we found the risk of non-melanoma skin cancers in PD was slightly higher (OR 1.20, 95 % CI 1.11–1.29) than general population. It was impossible to evaluate the association between PD and melanoma according to use of levodopa or gene polymorphism via meta-analysis since few observational or cohort studies have focused on it.

Conclusions

An association between PD and melanoma was confirmed. Most of the evidences were of high quality, and the conclusion was robust. Further research is needed to explore the mechanisms underlying this relationship.

Electronic supplementary material

The online version of this article (doi:10.1186/s40035-015-0044-y) contains supplementary material, which is available to authorized users.

The associations between Parkinson's disease and cancer: the plot thickens

Epidemiological studies support a general inverse association between the risk of cancer development and Parkinson’s disease (PD). In recent years however, increasing amount of eclectic evidence points to a positive association between PD and cancers through different temporal analyses and ethnic groups. This positive association has been supported by several common genetic mutations in SNCA, PARK2, PARK8, ATM, p53, PTEN, and MC1R resulting in cellular changes such as mitochondrial dysfunction, aberrant protein aggregation, and cell cycle dysregulation. Here, we review the epidemiological and biological advances of the past decade in the association between PD and cancers to offer insight on the recent and sometimes contradictory findings.

Diametrical diseases reflect evolutionary-genetic tradeoffs: Evidence from psychiatry, neurology, rheumatology, oncology and immunology

Tradeoffs centrally mediate the expression of human adaptations. We propose that tradeoffs also influence the prevalence and forms of human maladaptation manifest in disease. By this logic, increased risk for one set of diseases commonly engenders decreased risk for another, diametric, set of diseases. We describe evidence for such diametric sets of diseases from epidemiological, genetic and molecular studies in four clinical domains: (i) psychiatry (autism vs psychotic-affective conditions), (ii) rheumatology (osteoarthritis vs osteoporosis), (iii) oncology and neurology (cancer vs neurodegenerative disorders) and (iv) immunology (autoimmunity vs infectious disease). Diametric disorders are important to recognize because genotypes or environmental factors that increase risk for one set of disorders protect from opposite disorders, thereby providing novel and direct insights into disease causes, prevention and therapy. Ascertaining the mechanisms that underlie disease-related tradeoffs should also indicate means of circumventing or alleviating them, and thus reducing the incidence and impacts of human disease in a more general way.

The link between Parkinson's disease and breast and prostate cancers: A meta-analysis

PURPOSE

Clinical observations have shown an increased morbidity for breast cancer or prostate cancer in patients with Parkinson's disease (PD), however, other reports have noted contradictory results. This pooled analysis was utilized to test whether PD is associated with the risk of breast or prostate cancer.

METHODS

We searched PubMed, Embase and Cochrane library and conducted a meta-analysis to clarify the correlation of PD with breast and/or prostate cancer risk. We identified 16 eligible articles from which odds ratios with 95% confident intervals were assessed as main measures in the pooled estimation. Subgroup analyses and cumulative meta-analysis were also performed.

RESULTS

Our results showed no PD risk associated with breast or prostate cancer in the overall population, which was supported by the results of cumulative meta-analyses. The subgroup analyses suggested no significant risk of breast or prostate cancer in patients with PD within relevant subsets, i.e. gender, ethnicity, PD diagnosis time or study design. No evidence of publication bias was observed across the involved studies.

CONCLUSIONS

This meta-analysis indicates a lack of association between PD and risk of breast or prostate cancer.

Inverse and direct cancer comorbidity in people with central nervous system disorders: a meta-analysis of cancer incidence in 577,013 participants of 50 observational studies

BACKGROUND

There is a lack of scientific consensus about cancer comorbidity in people with central nervous system (CNS) disorders. This study assesses the co-occurrence of cancers in patients with 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).

METHOD

Comprehensive search in PubMed/MEDLINE, Scopus and ISI Web of Knowledge of the literature published before March 2013. We identified 51 relevant articles from 2,229 discrete references, 50 of which contained data suitable for quantitative synthesis (577,013 participants). Pooled effect sizes (ES) were calculated using multiple random-effects meta-analyses. Sources of heterogeneity and uncertainty were explored by means of subgroup and sensitivity analyses, respectively.

RESULTS

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; I(2) = 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; I(2) = 82.8%), and in those with AD (ES = 0.32; 95% CI: 0.22-0.46; I(2) = 0.0%), PD (ES = 0.83; 95% CI: 0.76-0.91; I(2) = 80.0%), MS (ES = 0.91; 95% CI: 0.87-0.95; I(2) = 30.3%) and HD (ES = 0.53; 95% CI: 0.42-0.67; I(2) = 56.4%). Patients with DS had a higher overall co-occurrence of cancer (ES = 1.46; 95% CI: 1.08-1.96; I(2) = 87.9%). No association was observed between cancer and ALS (ES = 0.97; 95% CI: 0.76-1.25; I(2) = 0.0%) or SCZ (ES = 0.98; 95% CI: 0.90-1.07; I(2) = 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).

CONCLUSION

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.

Periodontal disease with treatment reduces subsequent cancer risks

AIM

The aim of our study was to evaluate the relationship between routine treatment of periodontal disease (PD) and the subsequent risks for cancers in Taiwan.

METHODS

Study participants were selected from the Taiwan National Health Insurance (NHI) system database. The PD with a routine treatment cohort contained 38 902 patients. For each treatment cohort participant, two age- and sex-matched comparison (control) cohort participants were randomly selected. Cox's proportional hazards regression analysis was used to estimate the effects of PD with treatment on the subsequent risk of cancer.

RESULTS

The overall risk of developing cancer was significantly lower in the treatment cohort than in the patients without treatment (adjusted Hazard ratio = 0.72, 95% confidence interval = 0.68-0.76). The risks of developing most gastrointestinal tract, lung, gynecological and brain malignancies were significantly lower in the treatment cohort than in the comparison cohort. In contrast, the risks of prostate and thyroid cancers were significantly higher in the treatment cohort than in the comparison cohort.

CONCLUSIONS

Our findings suggest that PD with treatment is associated with a significantly reduced overall risk of cancer and reduced risks of certain types of cancers.

Is the risk of motor neuron disease increased or decreased after cancer? An Australian case-control study

Cancer appears to be inversely associated with both Alzheimer's and Parkinson's disease. The relationship between cancer and sporadic motor neuron disease (SMND), however, remains uncertain. Most previous cancer-SMND studies have been undertaken in northern hemisphere populations. We therefore undertook a case-control study to see if a link between cancer and SMND exists in an Australian population. A questionnaire was used to compare past cancer diagnoses in 739 SMND patients and 622 controls, recruited across Australia. Odds ratios with 95% confidence intervals were calculated to look for associations between cancer and SMND. A history of cancer was not associated either positively or negatively with a risk of subsequent SMND. This result remained when age, gender, smoking status, and the four SMND diagnostic subgroups were taken into account. No association was observed between SMND and specific tumours, including melanoma, a common malignancy in Australia. In conclusion, this Australian case-control study does not support an association between a past history of cancer and the development of SMND. This suggests that some pathogenetic mechanisms, such as apoptosis, are less relevant in SMND than in other neurodegenerative diseases where negative associations with cancer have been found.

Clinical features in association with neurodegenerative diseases and malignancies

OBJECTIVE

To examine whether there are clinical features in Japanese patients with both neurodegenerative diseases and cancers.

METHODS

We analyzed the clinical characteristics of consecutive Japanese patients with neurodegenerative diseases during the past 5 years, including amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), dementia with Lewy bodies, progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), and multiple system atrophy (MSA).

RESULTS

Out of 292 patients, 39 patients had cancers, including a past history, as follows: ALS, n = 16; PD, n = 8; PSP, n = 7; CBD, n = 1, and MSA, n = 7. About 10% of patients with neurodegenerative diseases developed cancer after onset of the disease; about 30% of patients with ALS, PD, or PSP occurring with cancers died of cancer. Gastric cancer was most common before the onset of ALS (62.5%) but did not develop after the onset of ALS. Conversely, PD patients frequently developed gastric cancers after the onset of neurological signs (60.0%) in spite of no cancer before the onset of PD. The proportion of breast cancer in MSA (45.5%) was significantly higher than in other neurodegenerative diseases.

CONCLUSION

ALS, PD, or MSA patients with cancer showed clinical characteristics unique to each neurodegenerative disease in Japan compared to other countries.