Association of diabetes with prostate cancer risk in the multiethnic cohort

Prostate cancer incidence and prostate-specific antigen testing among HIV-positive and HIV-negative men

BACKGROUND

We investigated whether the reported lower incidence of prostate cancer in HIV-positive men is a result of confounding factors or reduced screening.

METHODS

We conducted a cohort study of 17,424 HIV-positive and 182,799 HIV-negative men enrolled in Kaiser Permanente (KP). Subjects were followed from the first KP enrollment after January 01, 1996 for KP Northern California (KPNC) and January 01, 2000 for KP Southern California until the earliest of prostate cancer diagnosis, loss to follow-up, or December 31, 2007. Poisson regression was used to compare cancer rates by HIV status adjusting for age, race, smoking, alcohol/drug abuse, overweight/obesity, and diabetes. For the KPNC subset, we analyzed additional available data by HIV status on testosterone deficiency, and on prostate-specific antigen (PSA) tests as a proxy for cancer screening.

RESULTS

The prostate cancer incidence rate was 102/100,000 person-years in HIV-positive men (n = 74 cases) and 131/100,000 person-years in HIV-negative men (n = 1195 cases), with an adjusted rate ratio of 0.73 (95% confidence interval: 0.57 to 0.92; P = 0.008). The reduced risk among HIV-positive men was greater for higher-stage cancers, which are less likely to be biased by screening differences than lower-stage cancers. In the KPNC subset, more HIV-positive (90.8%) than HIV-negative men (86.2%) received a PSA test by age 55 (P < 0.001). Decreased risk for HIV-positive men remained when examined only among those with a previous PSA test, and with adjustment for testosterone deficiency (rate ratio = 0.55; 95% confidence interval: 0.39 to 0.80; P = 0.001).

CONCLUSIONS

Prostate cancer incidence rates are lower in HIV-positive compared with HIV-negative men, which is not explained by screening differences or the risk factors evaluated.

CARING (CAncer Risk and INsulin analoGues): the association of diabetes mellitus and cancer risk with focus on possible determinants - a systematic review and a meta-analysis

Background:

Patients suffering from diabetes mellitus (DM) may experience an increased risk of cancer; however, it is not certain whether this effect is due to diabetes per se.

Objective:

To examine the association between DM and cancers by a systematic review and meta-analysis according to the PRISMA guidelines.

Data Sources:

The systematic literature search includes Medline at PubMed, Embase, Cinahl, Bibliotek.dk, Cochrane library, Web of Science and SveMed+ with the search terms: “Diabetes mellitus”, “Neoplasms”, and “Risk of cancer”.

Study Eligibility Criteria:

The included studies compared the risk of cancer in diabetic patients versus non-diabetic patients. All types of observational study designs were included.

Results:

Diabetes patients were at a substantially increased risk of liver (RR=2.1), and pancreas (RR=2.2) cancer. Modestly elevated significant risks were also found for ovary (RR=1.2), breast (RR=1.1), cervix (RR=1.3), endometrial (RR=1.4), several digestive tract (RR=1.1-1.5), kidney (RR=1.4), and bladder cancer (RR=1.1). The findings were similar for men and women, and unrelated to study design. Meta-regression analyses showed limited effect modification of body mass index, and possible effect modification of age, gender, with some influence of study characteristics (population source, cancer- and diabetes ascertainment).

Limitations:

Publication bias seemed to be present. Only published data were used in the analyses.

Conclusions:

The systematic review and meta-analysis confirm the previous results of increased cancer risk in diabetes and extend this to additional cancer sites. Physicians in contact with patients with diabetes should be aware that diabetes patients are at an increased risk of cancer.

Prostate Cancer Related JAZF1 Gene is Associated with Schizophrenia

BACKGROUND

Epidemiological studies have shown that there is a reduced risk of prostate cancer among persons diagnosed with schizophrenia (SCZ). However, the mechanism of such relationship is not clear. The reduced incidence of cancer observed in SCZ patients may be related to differences in genetic background. Recently, the JAZF1 gene is found to be associated with prostate cancer and type 2 diabetes. However, no study has focused on the association of JAZF1 with the risk of SCZ.

METHODS

We examined genetic associations of 118 single-nucleotide polymorphisms (SNPs) within the JAZF1 gene with SCZ using one European American (EA) sample of 1,149 cases and 1,347 controls. Logistic regression analysis of SCZ as a binary trait was performed using PLINK software.

RESULTS

The most significant association with SCZ was observed with rs10258132 (p = 0.0011); while the next best signal was rs17156259 (p = 0.0031). The third best associated SNP was rs7791865 (p = 0.00889). In addition, haplotype analyses revealed that the A-C haplotype from rs10244184 and rs10258132 was associated with SCZ (p = 0.00093); and the G-G haplotype from rs17156238 and rs17156259 was associated with SCZ (p = 0.00455).

CONCLUSION

These findings provide evidence of several genetic variants in JAZF1 gene influencing the risk of SCZ and will serve as a resource for replication in other populations.

Type 2 diabetes: a protective factor for prostate cancer? An overview of proposed mechanisms

Diabetes mellitus and prostate cancer are 2 of the most important public health concerns, especially in the elderly population. Although diabetes has been recognized as a potent risk factor for many types of cancers, there is a large amount of evidence that shows that it has a protective role against prostate cancer. The underlying cause of this protective role is not fully understood, however, some mechanisms have been proposed in this area. In the present study we have reviewed these mechanisms and some new mechanisms are also proposed.

Cancer risks among patients with type 2 diabetes: a 10-year follow-up study of a nationwide population-based cohort in Taiwan

BACKGROUND

This study aims to determine cancer risks among patients with type 2 diabetes through a follow-up study on a nationwide population-based cohort that included Taiwanese diabetic patients and general population in Taiwan as well as to estimate the population attributable fraction (PAF) of site-specific cancer risks that can be attributed to type 2 diabetes in Taiwanese population by using standardized incidence ratios (SIRs, 95% CI).

METHODS

Subjects with type 2 diabetes consisted of 472,979 patients aged ≥ 20 years, whereas general population consisted of 9,411,249 individuals of the same age limit but are not diabetic. Subjects were identified from 1997 to 1998 and followed up until December 31, 2007 or until the first manifestation of any cancer.

RESULTS

Cancer sites with increased risks in men, which were consistent with the main and sensitivity analyses, included pancreas (SIR=1.62; 95% CI=1.53 to 1.72), liver (1.61; 1.57 to 1.64), kidney (1.32; 1.25 to 1.40), oral (1.16, 1.12 to 1.21), and colorectal (1.19, 1.15 to 1.22). Cancer sites with increased risks in women included liver (1.55; 1.51 to 1.60), pancreas (1.44; 1.34 to 1.55), kidney (1.38; 1.30 to 1.46), endometrium (1.36; 1.26 to 1.47), bladder (1.19; 1.11 to 1.27), colorectal (1.16; 1.13 to 1.20), and breast (1.14; 1.09 to 1.18). Overall, PAFs were highest for liver cancer in men (4.0%) and women (3.7%), followed by pancreas (3.4%) and kidney (1.6%) cancers in men, and then for endometrium (1.8%) and kidney (1.8%) cancers in women.

CONCLUSION

Our data suggested that increased cancer risks are associated with type 2 diabetes.

Cancer biology in diabetes

Diabetes is a serious metabolic disease that causes multiple organ dysfunctions. Recent evidence suggests that diabetes could contribute to the initiation and progression of certain cancers in addition to the classic diabetic complications. Furthermore, some of the drugs used clinically to treat patients with diabetes might affect cancer initiation, progression and mortality. The recent discovery of the possible anticancer effects of metformin, a classic antidiabetic drug, has led physicians and scientists to reconsider the interaction between diabetes and cancer. In the present review, we analyze recent reports in this field, and explore possible mechanistic links between diabetes and cancer biology.

[Metabolic syndrome and prostate cancer]

The relationship between metabolic syndrome (MS) and prostate cancer (PCA) is highly complex and harbors multiple facets not least because MS is not a single entity but represents a poorly defined inhomogeneous mixture of different diseases and conditions. Although numerous studies suggest a correlation between MS or components of MS and the development of prostate cancer, current evidence cannot be considered convincing. While diabetes appears to be inversely related to PCA, increased serum levels of triglycerides, cholesterol and insulin-like growth factor 1 (IGF-1) may be predictive for high grade disease. Further studies suggested that MS and high serum insulin levels are independent predictors of an unfavorable prognosis in patients with metastatic PCA. Early detection and improved therapeutic options have dramatically prolonged the course of the disease in advanced PCA through the last decades. As a consequence, development of MS in patients undergoing hormone therapy along with the cardiovascular risks has gained increasing relevance. Based on this evolution prevention, early detection and sustainable therapy represent an important clinical challenge to modern urologists active in urooncology.

Diabetes and cancer relationships

Diabetes and cancer are both heterogeneous and multifactorial diseases with tremendous impact on health worldwide. Epidemiologic evidence suggests that certain malignancies may be associated with diabetes, as well as with diabetes risk factors and, perhaps, with certain diabetes treatments. Numerous biological mechanisms could account for these relationships. Insulin-like growth factor (IGF)-1, IGF-2, IGF-1 receptors, insulin, and the insulin receptor play roles in the development and progression of cancers. Although evidence from randomized controlled trials does not support or refute associations of diabetes and its treatments with either increased or reduced risk of cancer incidence or prognosis, consideration of malignancy incidence rates and the magnitude of the trials that would be required to address these issues explains why such studies may not be readily undertaken.

Alzheimer disease and cognitive impairment associated with diabetes mellitus type 2: associations and a hypothesis

INTRODUCTION

Epidemiological studies have demonstrated that patients with diabetes mellitus have an increased risk of developing Alzheimer disease, but the relationship between the 2 entities is not clear.

DEVELOPMENT

Both diseases exhibit similar metabolic abnormalities: disordered glucose metabolism, abnormal insulin receptor signalling and insulin resistance, oxidative stress, and structural abnormalities in proteins and β-amyloid deposits. Different hypotheses have emerged from experimental work in the last two decades. One of the most comprehensive relates the microvascular damage in diabetic polyneuritis with the central nervous system changes occurring in Alzheimer disease. Another hypothesis considers that cognitive impairment in both diabetes and Alzheimer disease is linked to a state of systemic oxidative stress. Recently, attenuation of cognitive impairment and normalisation of values in biochemical markers for oxidative stress were found in patients with Alzheimer disease and concomitant diabetes. Antidiabetic drugs may have a beneficial effect on glycolysis and its end products, and on other metabolic alterations.

CONCLUSIONS

Diabetic patients are at increased risk for developing Alzheimer disease, but paradoxically, their biochemical alterations and cognitive impairment are less pronounced than in groups of dementia patients without diabetes. A deeper understanding of interactions between the pathogenic processes of both entities may lead to new therapeutic strategies that would slow or halt the progression of impairment.

Diabetes and prostate cancer screening in black and white men

PURPOSE

Prior studies conducted primarily among white men find a reduced risk of prostate cancer associated with time since developing diabetes. While biologic explanations are plausible, the association may in part arise from more frequent prostate cancer screening among those with a diabetes diagnosis. The purpose of the present study was to investigate the association between diabetes and prostate cancer screening.

METHODS

We examined differences in prostate cancer screening (prostate-specific antigen and/or digital rectal examination) testing practices after a diabetes diagnosis among lower-income persons living in the southeastern United States and enrolled in the Southern Community Cohort Study between 2002 and 2009. Baseline in-person interviews collected information on history of diabetes and prostate cancer screening from 18,809 black and 6,404 white men aged 40-79 years.

RESULTS

After adjustment for confounding, diabetic black [odds ratio (OR) 1.12, 95 % confidence interval (CI) 1.01-1.25] and white (OR 1.25, 95 % CI 1.03-1.51) men were more likely to undergo recent prostate cancer screening compared to non-diabetic men of the same race. The increased risk for prostate cancer screening, however, occurred primarily within the first 12 months after diabetes diagnosis.

CONCLUSIONS

Our results suggest that a diabetes diagnosis modestly increases the likelihood of having a prostate cancer screening test for both black and white men. The prevalence of screening was higher nearer to the time of diabetes diagnosis, which may contribute to an early increase in prostate cancer detection followed by lower prostate cancer detection after an extended time.

Diabetes protects from prostate cancer by downregulating androgen receptor: new insights from LNCaP cells and PAC120 mouse model

Type 2 diabetes has been associated with decreased risk of prostate cancer in observational studies, and this inverse association has been recently confirmed in several large cohort studies. However the mechanisms involved in this protective effect remain to be elucidated. The aim of the present study was to explore whether different features of type 2 diabetes (hyperinsulinemia, hyperglycemia and tumor necrosis factor alpha [TNF-α]) protect against the development of prostate cancer. For this purpose LNCaP cells were used for in vitro experiments and nude mice in which PAC120 (hormone-dependent human prostate cancer) xenografts had been implanted were used for in vivo examinations. We provide evidence that increasing glucose concentrations downregulate androgen receptor (AR) mRNA and protein levels through NF-κB activation in LNCaP cells. Moreover, there was a synergic effect of glucose and TNFα in downregulating the AR in LNCaP cells. By contrast, insulin had no effect on AR regulation. In vivo experiments showed that streptozotocin-induced diabetes (STZ-DM) produces tumor growth retardation and a significant reduction in AR expression in PAC120 prostate cancer mice. In conclusion, our results suggest that hyperglycemia and TNF-α play an important role in protecting against prostate cancer by reducing androgen receptor levels via NF-κB.

Effect of metformin on prostate cancer outcomes after radical prostatectomy

OBJECTIVE

Recent studies have shown a relative risk reduction in the incidence of prostate cancer in patients taking metformin. However, there are conflicting findings on the effect of metformin on established cases of prostate cancer. In this study we evaluated the effect of metformin on survival and pathologic outcomes in established prostate cancer.

MATERIALS AND METHODS

We retrospectively identified 12,052 patients who underwent radical prostatectomy between 1997 and 2010 at Mayo Clinic. Among these, 885 (7.3%) were diabetics, including 323 taking and 562 not taking metformin. Kaplan-Meier method was utilized to calculate rates of biochemical recurrence (BCR), systemic progression (SP), and all-cause mortality (ACM). Cox models were used to estimate the metformin hazard ratio (HR) adjusted for clinical and pathologic variables.

RESULTS AND CONCLUSIONS

Median follow-up was 5.1 years. In univariate analysis, metformin HR (95% confidence intervals) was not significant for BCR (1.13 [0.84, 1.52]; P = 0.40), SP (1.37 [0.69, 2.72]; P = 0.37), and ACM (1.32 [0.84, 2.05]; P = 0.23). After adjusting for covariates of interest, the HRs for metformin among diabetics remained nonsignificant for BCR (0.91 [0.67, 1.24]; P = 0.55), SP (0.83 [0.39, 1.74]; P = 0.62); and ACM (1.16 [0.73, 1.86]; P = 0.53). No significant difference was seen between metformin users and nonusers in the final pathologic Gleason score (P = 0.33), stage (P = 0.1), rate of positive surgical margins (P = 0.29), or tumor volume (P = 0.76). Metformin use was not associated with a risk reduction in BCR, SP, or ACM. Besides presenting survival data, our results describing metformin's effect on final pathology are unique.

Metabolic syndrome as a peculiar target for management of prostate cancer patients

An interesting and reciprocal association between the metabolic syndrome and prostate cancer has been identified. Metabolic alterations, such as hyperinsulinemia, increased levels of insulin growth factor-1, and insulin resistance could be on the basis of development and progression of many tumors, including prostate cancer, and changes in body composition, in turn, can represent some side effects of androgen deprivation therapy and novel drugs, such as mammalian target of rapamycin inhibitors. This review evaluates this interrelation between metabolic syndrome and prostate tumor scanning in many clinical and preclinical epidemiological studies and describes possible pathogenetic biological mechanisms. Finally, this article discusses feasible clinical implications for the management, prevention, diagnosis, prognosis, and treatment of patients affected by metabolic syndrome and prostate cancer, with particular attention to the metformin action.

Why are diabetics at reduced risk for prostate cancer? A review of the epidemiologic evidence

A large body of epidemiologic evidence provides strong support for the notion that type-2 diabetics are at decreased risk for prostate cancer. In this review article, we summarize the epidemiologic literature that explores the role of diabetes mellitus and related biomarkers in prostate cancer risk and detection, in order to create a better understanding of the potential mechanisms that underlie this inverse association. The bulk of the data supporting this association comes from the USA, as evidence for this association is less consistent in many other regions of the world. The relationship between diabetes and prostate cancer is suspected to be causal due to evidence of decreasing prostate cancer risk with increasing diabetes duration and lack of evidence for any confounding of this association. Hypothesized mechanisms for decreased prostate cancer risk among diabetics include (1) decreased levels of hormones and other cancer-related growth factors among diabetics, (2) the impact of diabetes on detection-related factors, such as prostate size, circulating prostate-specific antigen (PSA), and health-care seeking behaviors, (3) protective effects of diabetes medications, and (4) a protective effect of diabetes-induced vascular damage in the prostate. The evidence for screening-related factors is compelling, as diabetics appear to have reduced PSA and lower levels of health-care seeking behavior compared with nondiabetics. Furthermore, the inverse association between diabetes and prostate cancer is much less apparent in populations that do not perform biopsies based on PSA levels and in studies restricted to biopsied individuals. The inverse association appears to be stronger for low-grade disease, as compared with high-grade (Gleason >7), which is consistent with the observation that among patients receiving biopsy or prostate cancer treatment, diabetics are more likely to have high-grade disease as compared to nondiabetics, potentially resulting in worse outcomes for diabetics. Epidemiological research has reveals a great deal regarding the relationship between diabetes and prostate cancer risk, but additional research is needed to further clarify the mechanisms underlying this inverse association.

Diabetes mellitus and prostate cancer risk of different grade or stage: a systematic review and meta-analysis

AIM

Prior studies have reported that diabetes mellitus might reduce the overall prostate cancer risk. We examined this association by conducting a detailed meta-analysis of the studies published in peer-reviewed literature on the association between diabetes mellitus and prostate cancer risk of different stage or grade.

METHODS

A comprehensive search for articles of MEDLINE and EMBASE databases and bibliographies of retrieved articles published up to October 23, 2012 was performed. Methodological quality assessment of the trials was based on the Newcastle-Ottawa Scale. Meta-analysis was performed using STATA 12.0.

RESULTS

We included 9 studies in the meta-analysis (5 studies examining the relation of different stage only, 2 studies for grade only, and 2 studies for both grade and stage), and found an inverse association between diabetes mellitus and prostate cancer of different stage or grade. The relative risk (RRs) was moderately stronger for low grade (RR 0.74, 95% confidence interval (CI), 0.64-0.86) and localized disease (RR 0.72, 95% CI 0.67-0.76) compared with high grade (RR 0.78, 95% CI 0.67-0.90) and advanced disease (RR 0.85, 95% CI 0.75-0.97).

CONCLUSION

This study suggests an inverse relationship between diabetes mellitus and prostate cancer of different stage or grade. Possible biases underlying this association are discussed.

The impact of diabetes mellitus on survival in men with clinically localized prostate cancer treated with permanent interstitial brachytherapy

PURPOSE

Patients with cancer of any origin with preexisting diabetes mellitus (DM) are at increased risk for all-cause mortality compared with those without DM. However, the influence of DM on biochemical progression-free survival (bPFS), cause-specific survival (CSS), and overall survival (OS) has not been clearly defined for men with clinically localized prostate cancer treated with brachytherapy.

MATERIALS AND METHODS

From April 1995 to May 2006, 1624 consecutive patients underwent brachytherapy with or without supplemental therapies. A prebrachytherapy diagnosis of diabetes was present in 199 patients (12.3%). Median follow-up was 7.8 years. Cause of death was determined for each deceased patient. Patients with metastatic prostate cancer or castrate-resistant disease without obvious metastases who died of any cause were classified as dead of prostate cancer. All other deaths were attributed to the immediate cause of death.

RESULTS

In patients without (n=1425) and with (n=199) DM, CSS was 97.2% versus 100% (P=0.168), bPFS was 95.6% versus 95.7% (P=0.960), and OS was 77.3% versus 56.0% at 12 years (P=0.003). In Cox regression analysis, OS in nondiabetic patients was most closely related to patient age, coronary artery disease, tobacco consumption, and androgen deprivation. In patients with diabetes, OS was related to patient age and coronary artery disease. In patients without diabetes, CSS was associated with Gleason score and clinical stage. No patient with diabetes died of prostate cancer. Patients with DM were more likely to die of cardiovascular disease (17.8% vs. 12.4%, P=0.007).

CONCLUSIONS

DM does not impact CSS or bPFS after brachytherapy. OS is significantly lower in patients with diabetes due to more deaths from cardiovascular disease.

Association of type 2 diabetes susceptibility variants with advanced prostate cancer risk in the Breast and Prostate Cancer Cohort Consortium

Observational studies have found an inverse association between type 2 diabetes (T2D) and prostate cancer (PCa), and genome-wide association studies have found common variants near 3 loci associated with both diseases. The authors examined whether a genetic background that favors T2D is associated with risk of advanced PCa. Data from the National Cancer Institute's Breast and Prostate Cancer Cohort Consortium, a genome-wide association study of 2,782 advanced PCa cases and 4,458 controls, were used to evaluate whether individual single nucleotide polymorphisms or aggregations of these 36 T2D susceptibility loci are associated with PCa. Ten T2D markers near 9 loci (NOTCH2, ADCY5, JAZF1, CDKN2A/B, TCF7L2, KCNQ1, MTNR1B, FTO, and HNF1B) were nominally associated with PCa (P < 0.05); the association for single nucleotide polymorphism rs757210 at the HNF1B locus was significant when multiple comparisons were accounted for (adjusted P = 0.001). Genetic risk scores weighted by the T2D log odds ratio and multilocus kernel tests also indicated a significant relation between T2D variants and PCa risk. A mediation analysis of 9,065 PCa cases and 9,526 controls failed to produce evidence that diabetes mediates the association of the HNF1B locus with PCa risk. These data suggest a shared genetic component between T2D and PCa and add to the evidence for an interrelation between these diseases.

Metformin and prostate cancer: reduced development of castration-resistant disease and prostate cancer mortality

BACKGROUND

In vitro data and early clinical results suggest that metformin has desirable antineoplastic effects and has a theoretical benefit on castration-resistant prostate cancer (CRPC).

OBJECTIVE

To determine whether the use of metformin would be associated with improved clinical outcomes and a reduction in the development of CRPC.

DESIGN, SETTING, AND PARTICIPANTS

Data from 2901 consecutive patients (157 metformin, 162 diabetic non-metformin, and 2582 nondiabetic) with localized prostate cancer treated with external-beam radiation therapy from 1992 to 2008 were collected from a single institution in the United States.

INTERVENTION

Use of metformin in localized prostate cancer.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Univariate and multivariate regression models utilizing k-sample, Fine and Gray, Cox regression, log-rank, and Kaplan-Meier methods to assess prostate-specific antigen-recurrence-free survival (PSA-RFS), distant metastases-free survival (DMFS), prostate cancer-specific mortality (PCSM), overall survival (OS), and development of CRPC.

RESULTS AND LIMITATIONS

With a median follow-up of 8.7 yr, the 10-yr actuarial rates for metformin, diabetic non-metformin, and nondiabetic patients for PCSM were 2.7%, 21.9%, and 8.2% (log-rank p ≤ 0.001), respectively. Metformin use independently predicted (correcting for PSA, T stage, Gleason score, age, diabetic status, and androgen-deprivation therapy use) improvement in all outcomes compared with the diabetic non-metformin group; PSA-RFS (hazard ratio [HR]: 1.99 [1.24-3.18]; p=0.004), DMFS (adjusted HR: 3.68 [1.78-7.62]; p<0.001), and PCSM (HR: 5.15 [1.53-17.35]; p=0.008). Metformin use was also independently associated with a decrease in the development of CRPC in patients experiencing biochemical failure compared with diabetic non-metformin patients (odds ratio: 14.81 [1.83-119.89]; p=0.01). The retrospective study design was the primary limitation of the study.

CONCLUSIONS

To our knowledge, our results are the first clinical data to indicate that metformin use may improve PSA-RFS, DMFS, PCSM, OS, and reduce the development of CRPC in prostate cancer patients. Further validation of metformin's potential benefits is warranted.

Diabetes mellitus and risk of prostate cancer: an updated meta-analysis based on 12 case-control and 25 cohort studies

The association between diabetes and risk of prostate cancer has been investigated widely. However, study results remain inconsistent and contradictory. Using a meta-analytic approach, the present study explore the relationship incorporating more recent studies and provide more powerful evidence without the limitations of any individual study. Relevant studies were identified by searching Pubmed and the Cochrane Central Register of Controlled Trials through May 18, 2012. The strength of the relationship between diabetes mellitus and risk of prostate cancer was assessed using relative risk (RR). Either a fixed effects or random effects model was used to calculate the pooled RRs. Stratification analyses and sensitivity analyses were conducted, and publication bias was assessed by Egger's test and Begg's test. Twelve case-control studies involving 9,767 cases and 19,790 controls, and 25 cohort studies involving 118,825 cases were included. The person-years of follow-up ranged from 29,963 to 6,264,890 among included cohort studies. Diabetes was not significantly associated with incidence of prostate cancer in our analysis of case-control studies only (RR = 0.846, 95 % CI [0.710, 1.009]) or that of cohort studies only (RR = 0.925, 95 % CI [0.811, 1.054]). However, through subgroup analyses, statistically significant associations between diabetes and prostate cancer were found when considering population-based studies only (RR = 0.719, 95 % CI [0.637, 0.812]), cohort studies conducted in the United States (RR = 0.789, 95 % CI [0.727, 0.857]), and studies with follow-up of more than 5 years. Compared to risk of prostate cancer among people without diabetes, diabetic patients using insulin treatment experienced reduced incidence of prostate cancer in both case-control and cohort studies. The results suggest that diabetes mellitus is associated with decreased incidence of prostate cancer, specifically in the population of the United States. In addition, the time since onset of diabetes was positively associated with decreasing incidence of prostate cancer. The present conclusions should be considered carefully, however, and confirmed with further studies.

Type 2 diabetes and risk of prostate cancer: a meta-analysis of observational studies

BACKGROUND

Emerging evidence suggests that diabetes may increase the risk of cancers. However, available evidence on prostate cancer is conflicting. We therefore examined the association between Type 2 diabetes and risk of prostate cancer by conducting a detailed meta-analysis of all studies published regarding this subject.

METHODS

PubMed database and bibliographies of retrieved articles were searched for epidemiological studies (published between 1970 and 2011), investigating the relationship between Type 2 diabetes and prostate cancer. Pooled risk ratio (RR) was calculated using random-effects model. Subgroup, sensitivity analysis and cumulative meta-analysis were also done.

RESULTS

Forty-five studies (29 cohort and 16 case-control studies) involving 8.1 million participants and 132 331 prostate cancer cases detected a significant inverse association between Type 2 diabetes and risk of prostate cancer (RR 0.86, 95% confidence interval (CI) 0.80-0.92). For cohort studies alone, the RR was 0.87 (95% CI 0.80-0.94), and for case-control studies alone, the RR was 0.85 (95% CI 0.74-0.96). Sensitivity analysis done by excluding one outlier further strengthened our negative association (RR 0.83, 95% CI 0.78-0.87). No evidence of publication bias was observed.

CONCLUSIONS

This meta-analysis provides strongest evidence supporting that Type 2 diabetes is significantly inversely associated with risk of developing prostate cancer.

Androgens, diabetes and prostate cancer

Metabolic disorders such as diabetes, obesity and the metabolic syndrome have been shown to modulate prostate cancer (PCa) risk and aggressiveness in population-based and experimental studies. While associations between these conditions are modest and complex, two consistent findings have emerged. First, there is observational evidence that obesity and associated insulin excess are linked to increased PCa aggressiveness and worse outcomes. Secondly and somewhat paradoxically, long-standing diabetes may be protective against PCa development. This apparent paradox may be due to the fact that long-standing diabetes is associated with insulin depletion and decreased IGF1 signalling. Men with obesity or diabetes have moderate reductions in their androgen levels. The interconnectedness of metabolic and androgen status complicates the dissection of the individual roles of these factors in PCa development and progression. Metabolic factors and androgens may promote prostate carcinogenesis via multiple mechanisms including inflammation, adipokine action, fatty acid metabolism and IGF signalling. Moreover, androgen deprivation, given to men with PCa, has adverse metabolic consequences that need to be taken into account when estimating the risk benefit ratio of this therapy. In this review, we will discuss the current epidemiological and mechanistic evidence regarding the interactions between metabolic conditions, sex steroids and PCa risk and management.

Effect of diabetes mellitus on high-grade prostate cancer detection among Japanese obese patients with prostate-specific antigen less than 10 ng/mL

OBJECTIVE

To investigate the association of diabetes mellitus (DM) with prostate cancer (PCa) risk and grade among Japanese patients undergoing extended biopsy and to investigate how obesity modifies these relationships.

METHODS

We retrospectively evaluated the data from 2038 patients with a prostate-specific antigen (PSA) level <10 ng/mL undergoing initial extended biopsy at our institutions. The DM history was determined by self-report and medication use. Multivariate analyses of DM for PCa risk and grade were done using logistic regression. Moreover, we examined whether these associations were modified by the body mass index using subgroup analyses (nonobese <25 kg/m(2) or obese ≥25 kg/m(2)) and interaction tests. Cancer grade was classified according to the Gleason score (GS): low-grade (GS ≤6), intermediate-grade (GS 7), and high-grade (GS 8-10).

RESULTS

Of 2038 patients, obesity and DM was observed in 606 (30%) and 213 (11%), respectively. Also, 836 patients (41%) had positive biopsy findings. On multivariate analysis, we found no significant association of DM with the risk of overall PCa (P = .106) or the risk of low-grade (P = .735), intermediate-grade (P = .119), or high-grade (P = .110) disease. When stratified by obesity, the relative risk (RR) of PCa detection for diabetic men apparently increased with higher cancer grade (low grade, RR = 1.19, P = .71; intermediate grade, RR = 2.01, P = .099; high-grade, RR = 4.03, P = .025). However, in the nonobese men, no association was noted between DM and PCa risk, irrespective of grade. Obesity modified the effect of DM on high-grade disease risk with a trend (P for interaction = .087).

CONCLUSION

DM was associated with more aggressive PCa detection among Japanese obese patients with gray-zone PSA levels undergoing extended biopsy.

Annual fasting plasma glucose variation increases risk of cancer incidence and mortality in patients with type 2 diabetes: the Taichung Diabetes Study

The study aims to examine whether the annual variations in fasting plasma glucose (FPG) measurements, represented by the coefficient of variation (CV), predict cancer incidence and mortality in the subsequent years independent of traditional risk factors of type 2 diabetic patients. A computerized database of patients with type 2 diabetes of 30 years old and older (n=4805) enrolled in the Diabetes Care Management Program of a medical center before 2006 was analyzed using a time-dependent Cox's proportional hazards regression model. The mortality rates for the first, second, and third tertiles of the first annual FPG-CV were 8.64, 12.71, and 30.82 per 1000 person-years respectively. After adjusting for mean FPG, HbA1c, and other risk factors, the annual FPG-CV was independently associated with cancer incidence, cancer mortality, and cancer incidence or mortality, and the corresponding hazard ratios for the third vs first tertile of the annual FPG-CV were 3.03 (1.98, 4.65), 5.04 (2.32, 10.94), and 2.86 (1.91, 4.29) respectively. The annual variation in FPG was a strong predictor of cancer incidence and mortality in type 2 diabetic patients; therefore, glucose variation may be important in the clinical practice of care management and cancer prevention.

Association of obesity and diabetes with serum prostate-specific antigen levels in Japanese males

Patients with diabetes have been reported to be at an increased risk for cancers of the pancreas, liver, and colon; however, recent studies have suggested that men with diabetes are at a decreased risk for prostate cancer. Previous studies have found that obese men have lower serum prostate-specific antigen (PSA) concentrations than do non-obese men. Further understanding of how obesity and diabetes affect the PSA concentration may improve our ability to detect clinically relevant prostate tumors. This study examined the relationships among serum PSA level, obesity, and diabetes in apparently healthy Japanese males. We analyzed the baseline data from 2,172 Japanese males (age, 56.8 +/- 6.1 years [mean +/- SD]) who participated in the Japan Multi-Institutional Collaborative Cohort Study. Diabetes was defined as the presence of both a hemoglobin A1c (JDS) of > or = 6.1% and a fasting plasma glucose level of > or = 126 mg/dL, or a positive medical history. After adjusting for age, the PSA levels were elevated among males with a higher normal BMI (ranging from 23.0 to 24.9) and lowered among men with a BMI of > or = 25.0. In the stratified analysis, these significant differences in BMI categories were absent among diabetics. The mean PSA levels were significantly lower in diabetics than in non-diabetics among subjects aged 60 and over. Our findings suggest that the pre-overweight men had increased PSA levels, and the diabetes was associated with a reduction of PSA levels in elderly.

Prostate carcinogenesis with diabetes and androgen-deprivation-therapy-related diabetes: an update

Prostate cancer and the androgen deprivation therapy (ADT) thereof are involved in diabetes in terms of diabetes-associated carcinogenesis and ADT-related metabolic disorder, respectively. The aim of this study is to systematically review relevant literature. About 218,000 men are estimated to be newly diagnosed with prostate cancer every year in the United States. Approximately 10% of them are still found with metastasis, and in addition to them, about 30% of patients with nonmetastatic prostate cancer recently experience ADT. Population-based studies have shown that dissimilar to other malignancies, type 2 diabetes is associated with a lower incidence of prostate cancer, whereas recent large cohort studies have reported the association of diabetes with advanced high-grade prostate cancer. Although the reason for the lower prevalence of prostate cancer among diabetic men remains unknown, the lower serum testosterone and PSA levels in them can account for the increased risk of advanced disease at diagnosis. Meanwhile, insulin resistance already appears in 25–60% of the patients 3 months after the introduction of ADT, and long-term ADT leads to a higher incidence of diabetes (reported hazard ratio of 1.28–1.44). Although the possible relevance of cytokines such as Il-6 and TNF-α to ADT-related diabetes has been suggested, its mechanism is poorly understood.

The influence of type 2 diabetes and glucose-lowering therapies on cancer risk in the Taiwanese

Objective. To investigate the association between type 2 diabetes, glucose-lowering therapies (monotherapy with either metformin, sulphonylurea or insulin) and cancer risk in Taiwan. Methods. Using Taiwan's National Health Research Institutes database of 1,000,000 random subjects from 2000–2008, we found 61777 patients with type 2 diabetes (age ≥20 years) and 677378 enrollees with no record of diabetes. Results. After adjusting for age and sex, we found patients with diabetes to have significantly higher risk of all cancers (OR: 1.176; 95% CI: 1.149–1.204, P < 0.001). Diabetic patients treated with insulin or sulfonylureas had significantly higher risk of all cancers, compared to those treated with metformin (OR: 1.583; 95% CI: 1.389–1.805, P < 0.001 and OR: 1.784; 95% CI: 1.406–2.262, P < 0.001). Metformin treatment was associated with a decreased risk of colon and liver cancer compared to sulphonylureas or insulin treatment. Sulfonylureas treatment was associated with an increased risk of breast and lung cancer compared to metformin therapy. Conclusions. Taiwanese with type 2 diabetes are at a high risk of breast, prostate, colon, lung, liver and pancreatic cancer. Those treated with insulin or sulfonylureas monotherapy are more likely to develop colon and liver cancer than those treated with metformin.

African ancestry and its correlation to type 2 diabetes in African Americans: a genetic admixture analysis in three U.S. population cohorts

The risk of type 2 diabetes is approximately 2-fold higher in African Americans than in European Americans even after adjusting for known environmental risk factors, including socioeconomic status (SES), suggesting that genetic factors may explain some of this population difference in disease risk. However, relatively few genetic studies have examined this hypothesis in a large sample of African Americans with and without diabetes. Therefore, we performed an admixture analysis using 2,189 ancestry-informative markers in 7,021 African Americans (2,373 with type 2 diabetes and 4,648 without) from the Atherosclerosis Risk in Communities Study, the Jackson Heart Study, and the Multiethnic Cohort to 1) determine the association of type 2 diabetes and its related quantitative traits with African ancestry controlling for measures of SES and 2) identify genetic loci for type 2 diabetes through a genome-wide admixture mapping scan. The median percentage of African ancestry of diabetic participants was slightly greater than that of non-diabetic participants (study-adjusted difference = 1.6%, P<0.001). The odds ratio for diabetes comparing participants in the highest vs. lowest tertile of African ancestry was 1.33 (95% confidence interval 1.13-1.55), after adjustment for age, sex, study, body mass index (BMI), and SES. Admixture scans identified two potential loci for diabetes at 12p13.31 (LOD = 4.0) and 13q14.3 (Z score = 4.5, P = 6.6 × 10(-6)). In conclusion, genetic ancestry has a significant association with type 2 diabetes above and beyond its association with non-genetic risk factors for type 2 diabetes in African Americans, but no single gene with a major effect is sufficient to explain a large portion of the observed population difference in risk of diabetes. There undoubtedly is a complex interplay among specific genetic loci and non-genetic factors, which may both be associated with overall admixture, leading to the observed ethnic differences in diabetes risk.

The influence of antidiabetic medications on the development and progression of prostate cancer

BACKGROUND

The development of prostate tumors has been linked to co-morbid diabetes mellitus (DM) in several studies, potentially through the stimulation of insulin-like growth factor receptor (IGFR). This study evaluates the effect of anti-diabetic medication use on the development of high grade tumors and time to tumor progression compared to non-diabetics.

METHODS

This retrospective, nested case control study identified patients with prostate cancer (PCa) from the Kentucky Medicaid Database. Cases were diagnosed with PCa and DM and using at least one of the following antidiabetic medications; sulfonylureas, insulin, metformin or TZDs. Cases were further stratified on their insulin exposure resulting from therapy. Controls were those with PCa without DM or any anti-diabetic medications.

RESULTS

The use of metformin or TZDs trended toward decreased odds of high-grade tumors and decreased risk of progression, while sulfonylureas and high-dose insulin tended toward an increased odds of high-grade tumors and increase the risk of progression compared to non-diabetics.

CONCLUSIONS

Future studies should be conducted to further evaluate the effects of anti-diabetic medications on tumor grade and time to prostate cancer progression.

Insulin use is not significantly predictive for prostate cancer mortality in diabetic patients: a 12-year follow-up study

What's known on the subject? and What does the study add? Even though a lower risk of prostate cancer has been reported in patients with diabetes, they may have a higher risk of cancer development involving the liver, pancreas, endometrium, colorectum, breast and bladder. Insulin may have mitogenic properties besides its metabolic function. However, whether exogenous insulin use for glycaemic control in diabetic patients could increase the risk of prostate cancer has rarely been studied. This is the first prospective follow-up study for up to 12 years to show that exogenous insulin use for glycaemic control in the diabetic patients is not significantly predictive for prostate cancer mortality.

OBJECTIVE

To evaluate whether insulin use in diabetic patients could be predictive for prostate cancer mortality.

PATIENTS AND METHODS

A total of 39 135 diabetic men aged ≥40 years from a nationally representative cohort were followed prospectively from 1995 to 2006 for prostate cancer mortality. Cox proportional hazards models were used to estimate the hazard ratios for the following independent variables: age, diabetes type, diabetes duration, body mass index, smoking, insulin use and area of residence. The models were created for patients aged ≥40 years and ≥65 years, separately; and before and after excluding patients with a duration between onset of diabetes and prostate cancer mortality <5 years.

RESULTS

A total of 105 diabetic men died of prostate cancer during follow-up. Age was the only significant risk factor. Insulin use was associated with an insignificantly higher risk of prostate cancer mortality ranging from 24% to 49%. When stratified by the duration of insulin use <5 and ≥5 years, a lack of significant association was also observed.

CONCLUSIONS

Insulin use in diabetic patients does not significantly predict the mortality from prostate cancer. Further confirmation in other ethnicities is needed.

HNF1B and endometrial cancer risk: results from the PAGE study

We examined the association between HNF1B variants identified in a recent genome-wide association study and endometrial cancer in two large case-control studies nested in prospective cohorts: the Multiethnic Cohort Study (MEC) and the Women's Health Initiative (WHI) as part of the Population Architecture using Genomics and Epidemiology (PAGE) study. A total of 1,357 incident cases of invasive endometrial cancer and 7,609 controls were included in the analysis (MEC: 426 cases/3,854 controls; WHI: 931 cases/3,755 controls). The majority of women in the WHI were European American, while the MEC included sizable numbers of African Americans, Japanese and Latinos. We estimated the odds ratios (ORs) per allele and 95% confidence intervals (CIs) of each SNP using unconditional logistic regression adjusting for age, body mass index, and four principal components of ancestry informative markers. The combined ORs were estimated using fixed effect models. Rs4430796 and rs7501939 were associated with endometrial cancer risk in MEC and WHI with no heterogeneity observed across racial/ethnic groups (P ≥ 0.21) or between studies (P ≥ 0.70). The OR(per allele) was 0.82 (95% CI: 0.75, 0.89; P = 5.63 × 10(-6)) for rs4430796 (G allele) and 0.79 (95% CI: 0.73, 0.87; P = 3.77 × 10(-7)) for rs7501939 (A allele). The associations with the risk of Type I and Type II tumors were similar (P ≥ 0.19). Adjustment for additional endometrial cancer risk factors such as parity, oral contraceptive use, menopausal hormone use, and smoking status had little effect on the results. In conclusion, HNF1B SNPs are associated with risk of endometrial cancer and that the associated relative risks are similar for Type I and Type II tumors.

East meets West: ethnic differences in prostate cancer epidemiology between East Asians and Caucasians

Prostate cancer is the most prevalent cancer in males in Western countries. The reported incidence in Asia is much lower than that in African Americans and European Caucasians. Although the lack of systematic prostate cancer screening system in Asian countries explains part of the difference, this alone cannot fully explain the lower incidence in Asian immigrants in the United States and west-European countries compared to the black and non-Hispanic white in those countries, nor the somewhat better prognosis in Asian immigrants with prostate cancer in the United States. Soy food consumption, more popular in Asian populations, is associated with a 25% to 30% reduced risk of prostate cancer. Prostate-specific antigen (PSA) is the only established and routinely implemented clinical biomarker for prostate cancer detection and disease status. Other biomarkers, such as urinary prostate cancer antigen 3 RNA, may increase accuracy of prostate cancer screening compared to PSA alone. Several susceptible loci have been identified in genetic linkage analyses in populations of countries in the West, and approximately 30 genetic polymorphisms have been reported to modestly increase the prostate cancer risk in genome-wide association studies. Most of the identified polymorphisms are reproducible regardless of ethnicity. Somatic mutations in the genomes of prostate tumors have been repeatedly reported to include deletion and gain of the 8p and 8q chromosomal regions, respectively; epigenetic gene silencing of glutathione S-transferase Pi (GSTP1); as well as mutations in androgen receptor gene. However, the molecular mechanisms underlying carcinogenesis, aggressiveness, and prognosis of prostate cancer remain largely unknown. Gene-gene and/or gene-environment interactions still need to be learned. In this review, the differences in PSA screening practice, reported incidence and prognosis of prostate cancer, and genetic factors between the populations in East and West factors are discussed.

The association of diabetes and positive prostate biopsy in a US veteran population

BACKGROUND

Several studies have shown a protective effect of diabetes mellitus (DM) on incidence of prostate cancer; however, the data are not consistent. Moreover, whether or not DM is associated with a positive result among patients referred for prostate biopsy due to abnormal PSA and/or abnormal digital rectal examination is not clear.

METHODS

A retrospective review of 3162 consecutive men who underwent prostate biopsy between January 2000 and July 2009 at the Atlanta Veterans Affairs Medical Center was performed. Men with positive and negative biopsies were compared for various demographic and clinical factors. The data were analyzed using logistic regression models with results expressed as adjusted odds ratios (ORs) with corresponding 95% confidence intervals (CI).

RESULTS

DM was associated with increased odds of positive biopsy in the overall cohort (OR 1.26, 95% CI: 1.01-1.55; P = 0.04). Subjects with DM had higher odds of more aggressive disease (Gleason ≥ 7) than those without the condition (OR 1.31, 95% CI: 0.98-1.74; P = 0.07). Race had no significant impact on these results.

CONCLUSIONS

In this large series of prostate biopsies, diabetes is associated with higher odds of positive biopsy and higher Gleason grade. More studies investigating the role of DM and its associated comorbidities in prostate carcinogenesis are needed.

Physical activity after diagnosis and risk of prostate cancer progression: data from the cancer of the prostate strategic urologic research endeavor

Vigorous activity after diagnosis was recently reported to be inversely associated with prostate cancer-specific mortality. However, men with metastatic disease may decrease their activity due to their disease; thus, a causal interpretation is uncertain. We therefore prospectively examined vigorous activity and brisk walking after diagnosis in relation to risk of prostate cancer progression, an outcome less susceptible to reverse causation, among 1,455 men diagnosed with clinically localized prostate cancer. Cox proportional hazards regression was used to examine vigorous activity, nonvigorous activity, walking duration, and walking pace after diagnosis and risk of prostate cancer progression. We observed 117 events (45 biochemical recurrences, 66 secondary treatments, 3 bone metastases, 3 prostate cancer deaths) during 2,750 person-years. Walking accounted for nearly half of all activity. Men who walked briskly for 3 h/wk or more had a 57% lower rate of progression than men who walked at an easy pace for less than 3 h/wk (HR = 0.43; 95% CI: 0.21-0.91; P = 0.03). Walking pace was associated with decreased risk of progression independent of duration (HR brisk vs. easy pace = 0.52; 95% CI: 0.29-0.91; P(trend) = 0.01). Few men engaged in vigorous activity, but there was a suggestive inverse association (HR ≥3 h/wk vs. none = 0.63; 95% CI: 0.32-1.23; P(trend) = 0.17). Walking duration and total nonvigorous activity were not associated with risk of progression independent of pace or vigorous activity, respectively. Brisk walking after diagnosis may inhibit or delay prostate cancer progression among men diagnosed with clinically localized prostate cancer.

The association of diabetes mellitus and high-grade prostate cancer in a multiethnic biopsy series

OBJECTIVE

To analyze the association of diabetes mellitus (DM) with risk of prostate cancer and cancer grade among men undergoing prostate biopsy and to analyze how obesity and race modify these associations.

MATERIALS AND METHODS

Retrospective analysis of 998 men from the Durham VA undergoing first prostate biopsy between 2001 and 2009 with complete data available. History of DM was determined by chart review. Patients' characteristics at biopsy were analyzed with chi-square and ranksum. Multivariable analyses of DM and risk of cancer and cancer grade were done using logistic regression adjusting for PSA, body mass index, race, age, year, and digital rectal exam.

RESULTS

At biopsy, 284 (28%) men had DM. DM was associated with African American (AAM; p = 0.010) and higher BMI (p < 0.001). DM was not associated with prostate cancer risk on either bivariate (p = 0.600) or multivariate analysis (p = 0.485). Similar results were found after stratification by race and obesity. In multivariable analysis, DM was associated with greater risk of high-grade disease (RR = 2.13, p = 0.024). The association was stronger among obese men (RR = 3.84, p = 0.020) and null in non-obese subjects (RR = 1.39, p = 0.460). After further stratification by race, DM was associated with high-grade disease only in obese Caucasian men (CM; RR = 5.81, p = 0.025) but not in obese AAM. DM was not associated with risk of low-grade disease in all men together or after stratification by obesity or race.

CONCLUSION

History of DM was associated with greater risk of high-grade disease. The association was strongest among obese CM suggesting the effect of DM on high-grade prostate cancer is modified by race and obesity.

Diabetes and urothelial cancer risk: the Multiethnic Cohort study

BACKGROUND

It is important to understand the adverse health sequelae that may result from the rising incidence of diabetes. Diabetics may have an increased risk for urothelial cancer but the evidence from prospective studies and ethnically diverse populations is sparse.

METHOD

We examined this association in the Multiethnic Cohort (MEC) that was conducted in Hawaii and Los Angeles with nearly 186,000 participants in five ethnic groups. Over a median 10.7 years of follow-up, 918 incident cases of urothelial cancer (89% bladder and 11% other urinary tract sites) were identified through tumor registry linkages.

RESULTS

A self-reported diagnosis of diabetes was associated with an increased risk of urothelial cancer (relative risk=1.25; 95% confidence interval: 1.04-1.50). The association was not explained by body mass index, physical activity, or smoking. There was some suggestion that the risk was higher in women, Whites and African Americans, and past smokers. The risk associated with diabetes for in situ and localized cancer was similar to that for regional and distant cancer.

CONCLUSION

This study demonstrates that the increased urothelial cancer risk with diabetes in this multiethnic population is very similar to that observed in mostly White or Asian populations. Whether or not the elevated risk is moderated by the degree of control of the hyperglycemia associated with diabetes will need to be determined in future studies.

Glucose metabolism disorders and the risk of cancer

Diabetes and cancer are diseases which take the size of an epidemic spread across the globe. Those diseases are influenced by many factors, both genetic and environmental. Precise knowledge of the complex relationships and interactions between these two conditions is of great importance for their prevention and treatment. Many epidemiological studies have shown that certain types of cancer, especially gastrointestinal cancers (pancreas, liver, colon) and also the urinary and reproductive system cancers in women are more common in patients with diabetes or related metabolic disorders. There are also studies showing the inverse relationship between diabetes and cancer, or the lack of it, but they are less numerous and relate mainly to prostate cancer or squamous cell carcinoma of the esophagus. Epidemiological studies, however, do not say anything about the mechanisms of these dependencies. For this purpose, molecular research is needed on the metabolism of cells (including tumor cells) and on metabolic dysfunctions that arise due to changes in the cell environment taking place in the sick, as well as in the intensely treated human organism.

Thiazolidinediones and metformin associated with improved survival of diabetic prostate cancer patients

BACKGROUND

The association between antidiabetic medications and the prognosis of human prostate cancer has not been explored. This study examined the impact of these drugs on the outcomes of diabetic patients with prostate cancer to provide a basis for diabetes management strategy in these patients.

PATIENTS AND METHODS

Records of consecutive prostate cancer patients with coexisting diabetes mellitus type 2 who were treated at the study institution between 15 July 1999 and 31 December 2008 were reviewed. The survival, cancer pathological grade, stage at the time of diagnosis, and antidiabetic pharmacotherapy of the patients were analyzed.

RESULTS

A total of 233 consecutive cases were analyzed. In Kaplan-Meier analysis, thiazolidinedione (log-rank, P = 0.005) and metformin (log-rank, P = 0.035) usage were significant predictors of improved overall survival, while insulin and insulin secretagogue usage were not significant predictors. Multivariate Cox regression analysis showed that thiazolidinedione {hazard ratio [HR] = 0.454 [95% confidence interval (CI) 0.213-0.965], P = 0.040} and metformin [HR = 0.550 (95% CI 0.315-0.960), P = 0.035] usage remained as significant predictors of favorable survival after controlling for variables including age, race, Gleason grade, and stage.

CONCLUSIONS

Thiazolidinediones and metformin appear to be associated with improved overall survival of diabetic prostate cancer patients. The choice of antidiabetic pharmacotherapy may influence overall survival of these patients.

Diabetes mellitus, fasting glucose, and risk of cause-specific death

BACKGROUND

The extent to which diabetes mellitus or hyperglycemia is related to risk of death from cancer or other nonvascular conditions is uncertain.

METHODS

We calculated hazard ratios for cause-specific death, according to baseline diabetes status or fasting glucose level, from individual-participant data on 123,205 deaths among 820,900 people in 97 prospective studies.

RESULTS

After adjustment for age, sex, smoking status, and body-mass index, hazard ratios among persons with diabetes as compared with persons without diabetes were as follows: 1.80 (95% confidence interval [CI], 1.71 to 1.90) for death from any cause, 1.25 (95% CI, 1.19 to 1.31) for death from cancer, 2.32 (95% CI, 2.11 to 2.56) for death from vascular causes, and 1.73 (95% CI, 1.62 to 1.85) for death from other causes. Diabetes (vs. no diabetes) was moderately associated with death from cancers of the liver, pancreas, ovary, colorectum, lung, bladder, and breast. Aside from cancer and vascular disease, diabetes (vs. no diabetes) was also associated with death from renal disease, liver disease, pneumonia and other infectious diseases, mental disorders, nonhepatic digestive diseases, external causes, intentional self-harm, nervous-system disorders, and chronic obstructive pulmonary disease. Hazard ratios were appreciably reduced after further adjustment for glycemia measures, but not after adjustment for systolic blood pressure, lipid levels, inflammation or renal markers. Fasting glucose levels exceeding 100 mg per deciliter (5.6 mmol per liter), but not levels of 70 to 100 mg per deciliter (3.9 to 5.6 mmol per liter), were associated with death. A 50-year-old with diabetes died, on average, 6 years earlier than a counterpart without diabetes, with about 40% of the difference in survival attributable to excess nonvascular deaths.

CONCLUSIONS

In addition to vascular disease, diabetes is associated with substantial premature death from several cancers, infectious diseases, external causes, intentional self-harm, and degenerative disorders, independent of several major risk factors. (Funded by the British Heart Foundation and others.).

Diabetes and risk of prostate cancer: a study using the National Health Insurance

OBJECTIVE

The link between diabetes and prostate cancer is rarely studied in Asians.

RESEARCH DESIGN AND METHODS

The trend of age-standardized prostate cancer incidence in 1995-2006 in the Taiwanese general population was calculated. A random sample of 1,000,000 subjects covered by the National Health Insurance in 2005 was recruited. A total of 494,630 men for all ages and 204,741 men ≥ 40 years old and without prostate cancer at the beginning of 2003 were followed to the end of 2005. Cumulative incidence and risk ratio between diabetic and nondiabetic men were calculated. Logistic regression estimated the adjusted odds ratios for risk factors.

RESULTS

The trend of prostate cancer incidence increased significantly (P < 0.0001). The cumulative incidence markedly increased with age in either the diabetic or nondiabetic men. The respective risk ratio (95% CI) for all ages and age 40-64, 65-74, and ≥ 75 years was 5.83 (5.10-6.66), 2.09 (1.60-2.74), 1.35 (1.07-1.71), and 1.39 (1.12-1.71). In logistic regression for all ages or for age ≥ 40 years, age, diabetes, nephropathy, ischemic heart disease, dyslipidemia, living region, and occupation were significantly associated with increased risk, but medications including insulin and oral antidiabetic agents were not.

CONCLUSIONS

Prostate cancer incidence is increasing in Taiwan. A positive link between diabetes and prostate cancer is observed, which is more remarkable in the youngest age of 40-64 years. The association between prostate cancer and comorbidities commonly seen in diabetic patients suggests a more complicated scenario in the link between prostate cancer and diabetes at different disease stages.

Prostate cancer mortality in Taiwanese men: increasing age-standardized trend in general population and increased risk in diabetic men

BACKGROUND

To evaluate the trend of prostate cancer mortality in Taiwanese general population and the association between diabetes and prostate cancer mortality.

MATERIALS AND METHODS

In the general population during 1995-2006, the trends of prostate cancer mortality were evaluated, followed by calculation of age-specific mortality rates for age 40-64, 65-74, and ≥ 75 years. A cohort of 102,651 diabetic men aged ≥ 40 years recruited in 1995-1998 was followed prospectively.

RESULTS

The trends of crude and age-standardized mortality from prostate cancer in the general population increased significantly (P < 0.0001). In the general population, 7,966 men aged ≥ 40 years died of prostate cancer, and aging was associated with increased risk. Age-specific prostate cancer mortality suggested significantly increasing trend for ages 65-74 and ≥ 75 years. A total of 321 diabetic men died of prostate cancer (crude mortality rate 41.9/100,000 person-years). Mortality rate ratios (95% confidence interval) showed higher risk of prostate cancer mortality in the diabetic patients, with magnitude increased with decreasing age: 1.55 (1.29-1.86), 2.68 (2.29-3.13), and 6.84 (5.34-8.75) for age ≥ 75, 65-74, and 40-64 years, respectively.

CONCLUSIONS

Prostate cancer mortality in the Taiwanese general population is increasing. Diabetic patients have a higher risk of prostate cancer mortality, which is more remarkable with decreasing age.

Risk of cancer in a large cohort of U.S. veterans with diabetes

Prior studies of cancer risk among diabetic men have reported inconsistent findings. The aim of this study was to assess the risk of cancer among a large cohort (n = 4,501,578) of black and white U.S. veterans admitted to Veterans Affairs hospitals. The cancer risk among men with diabetes (n = 594,815) was compared to the risk among men without diabetes (n = 3,906,763). Poisson regression was used to estimate adjusted relative risks (RRs) and 95% confidence intervals (CIs). Overall, men with diabetes had a significantly lower risk of cancer (RR = 0.93, 95%CI = 0.93-0.94). Men with diabetes, however, had increased risks of cancers of the liver (RR = 1.95, 95%CI = 1.82-2.09), pancreas (RR = 1.50, 95%CI = 1.42-1.59), biliary tract (RR = 1.41, 95%CI = 1.22-1.62), colon (RR = 1.20, 95%CI = 1.16-1.25), rectum (RR = 1.12, 95%CI = 1.07-1.18), and kidney (RR = 1.09, 95%CI = 1.03-1.16), as well as leukemia (RR = 1.14, 95%CI = 1.08-1.21) and melanoma (RR = 1.13, 95%CI = 1.03-1.24). In contrast, men with diabetes had decreased risks of cancers of the prostate (RR = 0.89, 95%CI = 0.87-0.91), brain (RR = 0.91, 95% CI = 0.82-0.99), buccal cavity (RR = 0.85, 95%CI = 0.82-0.89), lung (RR = 0.79, 95%CI = 0.77-0.80), esophagus (RR = 0.77, 95%CI = 0.72-0.82), and larynx (RR = 0.76, 95%CI = 0.71-0.80). These findings indicate that black and white men with diabetes are at significantly lower risk of total cancer and of two of the most common cancers among U.S. males; lung and prostate cancers. These decreased risks were offset, however, by increased risks of cancer at several sites. Hyperinsulinemia may explain the increased risks of the digestive cancers, while lower testosterone levels, in the case of prostate cancer, and higher BMI, in the case of lung cancer, may explain the decreased risks of those tumors.

Metformin and the incidence of prostate cancer in patients with type 2 diabetes

BACKGROUND

Several in vitro studies have indicated that metformin may reduce the risk of prostate cancer; however, epidemiologic studies have been inconclusive. The objective of this study was to determine whether metformin decreases the risk of prostate cancer in patients with type 2 diabetes.

METHODS

A nested case-control analysis was conducted within a population-based cohort from the UK General Practice Research Database. The cohort included patients over the age of 40 who were prescribed a first oral hypoglycemic agent (OHA) between 1988 and 2009. Cases of prostate cancer were matched up to ten controls on year of birth, date of cohort entry, and duration of follow-up. Adjusted rate ratios (RR) were estimated using conditional logistic regression.

RESULTS

The cohort included 63,049 incident users of OHAs, in which 739 cases of prostate cancer were matched to 7,359 controls. Metformin use did not decrease the risk of prostate cancer (RR: 1.23, 95% CI: 0.99-1.52). In secondary analyses, prostate cancer risk was found to increase as a function of the number of metformin prescriptions received (one to seven prescriptions: RR: 1.05, 95% CI: 0.80-1.37; seven to eighteen prescriptions: RR: 1.29, 95% CI: 0.99-1.69; eighteen to thirty-six prescriptions: RR: 1.37, 95% CI: 1.04-1.81; more than thirty-six prescriptions: RR: 1.40, 95% CI: 1.03-1.89).

CONCLUSION

The results of this study indicate that metformin does not reduce the risk of prostate cancer in patients with type 2 diabetes.

IMPACT

The secondary analyses need to be interpreted with caution given the inverse association between type 2 diabetes and prostate cancer.

The effects of type 2 diabetes and hypertension on changes in serum prostate specific antigen levels: results from the Olmsted County study

OBJECTIVE

Men with type 2 diabetes have lower concomitant prostate-specific antigen (PSA) levels; however, the influence of metabolic conditions on PSA changes over time remains unknown. Therefore, the goal of this study was to assess associations between type 2 diabetes and hypertension and changes in serum PSA levels.

METHODS

In 1990, a randomly selected cohort of Caucasian men, ages 40-79, from Olmsted County, MN completed questionnaires ascertaining demographic characteristics, current medical conditions and medications biennially, with 633 men undergoing blood draws. Men with a physician diagnosis of diabetes or hypertension at baseline, or who reported using medications to treat these conditions prior to baseline were considered exposed. Men with at least two serum PSA measurements (n = 569) were included in this analysis. Linear mixed models were used to estimate the annual percent change in serum PSA levels associated with diabetes and hypertension, adjusting for baseline age.

RESULTS

The overall mean change in serum PSA levels was 3.6% per year and increased with age (P = .009). Men with diabetes experienced less annual change in serum PSA levels (1.1%) than did non-diabetic men (3.7%), adjusting for age (P = .02). Age-adjusted change in serum PSA levels differed little by hypertension status (3.7% vs. 3.6%; P = .49).

CONCLUSIONS

Our results suggest that Caucasian men with type 2 diabetes experience smaller increases in serum PSA levels as they age compared to men without diabetes. Additional research is needed to elucidate whether this difference results in a relatively lower incidence of prostate cancer or less cancer detection among diabetic men.

Cancer and schizophrenia: is there a paradox?

People with schizophrenia are more likely to die prematurely than the general population from both suicide and physical ill health. Published studies examining the incidence of cancer in schizophrenia patients report increased, reduced or similar incidence compared with the general population. Older studies tended to report lower incidence rates which fuelled speculation as to the biological and other mechanisms for this protective effect. Furthermore, mortality rates in patients with schizophrenia appear higher than expected. We undertook a non-systematic review of published data to give an overview for these variable findings and illustrate methodological confounders by highlighting a systematic review of breast cancer studies.