Diabetes mellitus and prostate cancer risk

Poorly Controlled Diabetes Mellitus Increases the Risk of Deaths and Castration-Resistance in Locally Advanced Prostate Cancer Patients

The association between DM and prostate cancer progression remains controversial. Previous studies mainly focused on early stage prostate cancer patients. We aimed to study the association between DM and prostate cancer progression in locally advanced prostate cancer patients. 598 locally advanced prostate cancer patients in a top tertiary hospital in China between 2012 and 2021 were divided into three groups based on the postoperative average HbA1c level. The follow-up time is 46.96 ± 27.07 months. Three hundred and forty-eight (58.2%) were normal glucose, 175 (29.3%) were moderate glucose, and 75 (12.5%) were high glucose. Higher postoperative-average HbA1c was associated with poorer OS, PCSM, and PSA-RFS. We concluded that poorly controlled DM was correlated with poorer OS, PCSM, and PSA-RFS in locally advanced prostate cancer patients.

Reduced risk of prostate cancer in a cohort of Lithuanian diabetes mellitus patients

BACKGROUND

During the past decade, a huge interest was devoted to the type-2 diabetes mellitus and their associations with prostate cancer development.

OBJECTIVES

The aim of this study was to determine whether type 2 diabetes mellitus and treatment with metformin is associated with prostate cancer risk.

MATERIALS AND METHODS

The cohort was composed of diabetic male patients identified in the National Health Insurance Fund database during 2000-2016 and cancer cases in national Cancer Registry. We calculated standardized incidence ratios (SIR) for prostate cancers as a ratio of observed number of cancer case in people with diagnosis of diabetes to the expected number of cancer cases in the underlying general population.

RESULTS

2754 prostate cancers were observed versus 3111.26 expected within the period of observation entailing an SIR of 0.89 (95% CI: 0.85-0.92). Significantly lower risk of prostate cancer was found in diabetes patients in all age groups, also was in metformin-users and never-users' groups, with higher risk reduction in metformin-users (SIR 0.71, 95% CI: 0.68-0.75) than in diabetes patients never-users (SIR 0.88, 95% CI: 0.80-0.96).

CONCLUSION

In this large population-based study, we found a significantly decreased risk of prostate cancer among men with diabetes and metformin-users.

Metabolic Alterations, Aggressive Hormone-Naïve Prostate Cancer and Cardiovascular Disease: A Complex Relationship

Background: Epidemiological studies suggest a possible relationship between metabolic alterations, cardiovascular disease and aggressive prostate cancer, however, no clear consensus has been reached. Objective: The aim of the study was to analyze the recent literature and summarize our experience on the association between metabolic disorders, aggressive hormone-naïve prostate cancer and cardiovascular disease. Method: We identified relevant papers by searching in electronic databases such as Scopus, Life Science Journals, and Index Medicus/Medline. Moreover, we showed our experience on the reciprocal relationship between metabolic alterations and aggressive prostate cancer, without the influence of hormone therapy, as well the role of coronary and carotid vasculopathy in advanced prostate carcinoma. Results: Prostate cancer cells have an altered metabolic homeostatic control linked to an increased aggressivity and cancer mortality. The absence of discrimination of risk factors as obesity, systemic arterial hypertension, diabetes mellitus, dyslipidemia and inaccurate selection of vascular diseases as coronary and carotid damage at initial diagnosis of prostate cancer could explain the opposite results in the literature. Systemic inflammation and oxidative stress associated with metabolic alterations and cardiovascular disease can also contribute to prostate cancer progression and increased tumor aggressivity. Conclusions: Metabolic alterations and cardiovascular disease influence aggressive and metastatic prostate cancer. Therefore, a careful evaluation of obesity, diabetes mellitus, dyslipidemia, systemic arterial hypertension, together with a careful evaluation of cardiovascular status, in particular coronary and carotid vascular disease, should be carried out after an initial diagnosis of prostatic carcinoma.

A stage-dependent link between metabolic syndrome components and incident prostate cancer

Metabolic syndrome is associated with increased cancer risk and progression at almost all sites, including the prostate in high-stage prostate cancer. However, several reports have described an inverse relationship between metabolic syndrome and its components and low-stage incident prostate cancer. Such anomalies in cancer research hamper efforts to fight cancer. Evidence suggests that metabolic syndrome and its components have two distinct effects in prostate cancer, concealing prostate cancer in low-stage disease and promoting progression to high-stage incident, nonlocalized, and lethal prostate cancer. The concealment of prostate cancer by metabolic syndrome and its components might be related to bias mechanisms that reduce PSA level and lead to a delayed diagnosis of low-stage prostate cancer, meaning that fewer men with metabolic syndrome are diagnosed with low-stage disease. The inverse link between metabolic syndrome and its components and low-stage incident prostate cancer might simply be the result of such bias and the shortcomings of the diagnostic procedure rather than being related to prostate cancer biology itself. The evidence summarized here supports the hypothesis that the link between metabolic syndrome and its components and incident prostate cancer is a two-way and stage-dependent one, a theory that requires further research.

The association of diabetes and obesity with prostate cancer aggressiveness among Black Americans and White Americans in a population-based study

PURPOSE

Few studies have investigated the role of race in the association of diabetes and obesity with prostate cancer aggressiveness. Here we evaluate the independent association between diabetes and obesity with prostate cancer aggressiveness in White Americans and Black Americans.

METHODS

Our cross-sectional, case-only study consisted of 1,058 White Americans and 991 Black Americans from the North Carolina-Louisiana Prostate Cancer (PCaP) project. Diabetes status was determined by self-report. Obesity was determined using body mass index and calculated based on anthropometric measurements. High aggressive prostate cancer was defined as Gleason sum ≥8, or prostate-specific antigen >20 ng/ml, or Gleason sum = 7 and clinical stage cT3-cT4. The association between diabetes and obesity with high aggressive prostate cancer at diagnosis was evaluated using multivariable logistic regression and adjusted for potential confounders.

RESULTS

Diabetes was not associated with high aggressive prostate cancer in the overall sample (OR 1.04; 95% CI 0.79, 1.37), White Americans (OR 1.00; 95% CI 0.65, 1.57) or Black Americans (OR 1.07; 95% CI 0.75, 1.53). Obesity, independent of diabetes, was positively associated with high aggressive prostate cancer in White Americans (OR 1.98; 95% CI 1.14, 3.43), but not in the overall sample (OR 1.37; 95% CI 0.99, 1.92) or Black Americans (OR 1.09; 95% CI 0.71, 1.67).

CONCLUSIONS

Diabetes was not associated with prostate cancer aggressiveness, overall, or in either race group. Obesity, independent of diabetes, was associated with high aggressive prostate cancer only in White Americans.

Cancer incidence in patients with type 2 diabetes mellitus: a population-based cohort study in Shanghai

BACKGROUND

Type 2 diabetes mellitus (T2DM) has been suggested to increase the risk of cancers. The aim of this study was to investigate the risk of common cancers in Chinese patients with T2DM.

METHODS

A population-based retrospective cohort study including 36,379 T2DM patients was conducted in Minhang District of Shanghai, China, during 2004 to 2010. All T2DM patients were enrolled from the standardized management system based on local electronic information system. Newly-diagnosed cancer cases were identified by record-linkage with the Shanghai Cancer Registry. Standardized incidence ratios (SIR) and 95% confidence interval (CI) were used to estimate the risk of cancers among T2DM patients.

RESULTS

Overall crude incidence rate (CIR) of cancers was 955.21 per 105 person-years in men and 829.57 per 105 person-years in women. Increased risk of cancer was found in both gender, with an SIR being 1.28 (95% CI = 1.17-1.38) in men and 1.44 (95% CI =1.32-1.55) in women. Increased risk of colon (SIR = 1.97; 95% CI = 1.49 to 2.46), rectum (1.72; 1.23 to 2.21), prostate (2.87; 2.19 to 3.56), and bladder cancers (1.98, 1.28 to 2.68) were observed in men and elevated risk of colon (1.67; 1.25 to 2.08), breast (1.66; 1.38 to 1.95), and corpus uteri cancers (2.87; 2.03 to 3.71) were observed in women.

CONCLUSIONS

Our results indicate that Chinese patients with T2DM may have an increased risk of some cancers, and the increase may vary by sub-sites of cancers.

Diabetes mellitus and the risk of prostate cancer: an update and cumulative meta-analysis

INTRODUCTION

To provide further insight into the association between type 2 diabetes mellitus (T2DM) and the pathophysiology of prostate cancer, we conducted an updated, detailed meta-analysis of 56 published case-control and cohort studies.

METHODS

MEDLINE and EMBASE were used to identify the literature published in April 2012 related to both diabetes mellitus and prostate cancer. A sensitivity analysis was performed, and potential confounding effects were investigated using a stratified meta-analysis. A cumulative meta-analysis was also carried out to evaluate the cumulative effect estimate over time.

RESULTS

A total of 24 case-control and 32 cohort studies with information on a total of ~8,000,000 subjects and ~140,000 individuals with prostatic cancer showed published estimates of the association between diabetes and prostate cancer malignancy. The pooled effect estimate revealed a relative risk (RR) of 0.88 (95% CI, 0.82-0.93). Interestingly, there was an increased trend for Asians (RR = 1.72, n = 7) but not Americans (RR = 0.82, n = 28) and Europeans (RR = 0.86, n = 21) regarding the association between diabetes mellitus and prostate cancer. The sensitivity analysis, excluding any one study, did not significantly change the pooled RR. The range for the pooled RR when one study was omitted was 0.84-0.89.

DISCUSSION

The findings of our meta-analysis provide strong evidence of an inverse association between diabetes and prostate cancer.

CONCLUSIONS

Further research should focus on limitations in the current literature and re-assess the relationship between diabetes and prostate cancer by analyzing the two different diabetes mellitus types separately.

Association of six susceptibility Loci with prostate cancer in northern chinese men

BACKGROUND/AIM

Six prostate cancer (PCa) susceptibility loci were identified in a genome-wide association study (GWAS) in populations of European decent. However, the associations of these 6 single-nucleotide polymorphisms (SNPs) with PCa has remained tobe clarified in men in Northern China. This study aimed to explore the loci associated with PCa risk in a Northern Chinese population.

METHODS

Blood samples and clinical information of 289 PCa patients and 288 controls from Beijing and Tianjin were collected. All risk SNPs were genotyped using polymerase chain reaction (PCR)-high resolution melting curve technology and gene sequencing. Associations between PCa and clinical covariates (age at diagnosis, prostate-specific antigen [PSA], Gleason score, tumor stage, and level of aggressiveness) and frequencies of alleles and genotypes of these SNPs were analyzed using genetic statistics.

RESULTS

Among the candidate SNPs, 11p15 (rs7127900, A) was associated with PCa risk (P = 0.02, odds ratio [OR] = 1.64, 95% confidence interval [CI] = 1.09-2.46). Genotypes showed differences between cases and controls on 11p15 (rs7127900, A), 11q13 (rs7931342, T), and HNF1B (rs4430796, A) (P = 0.03, P = 0.01, and P = 0.04, respectively). The genotype TG on 11q13 (rs7931342, T) was positively associated with an increased Gleason score (P = 0.04, OR = 2.15, 95% CI = 1.02-4.55). Patients carrying TG on 17q24 (rs1859962, G) were negatively associated with an increased body mass index (BMI) (P = 0.03, OR = 0.44, 95% CI = 0.21-0.92) while those with AG on HNF1B (rs4430796, A) were more likely to have PSA increase (P = 0.002).

CONCLUSION

Our study suggests that 11p15 (rs7127900, A) could be a susceptibility locus associated with PCa in Northern Chinese. Genotype TG on 11q13 (rs7931342, T) could be related to an increased Gleason score, AG on HNF1B (rs4430796, A) could be associated with PSA increase, and TG on 17q24 (rs1859962, G) could be negatively associated with an increased BMI in Chinese men with PCa.

Prostate cancer risk in pre-diabetic men: a matched cohort study

BACKGROUND

Diagnosis and duration of type 2 diabetes mellitus (DM) appear to be associated with decreased prostate cancer risk. Limitations of previous studies include methods of subject selection and accurate definition of DM diagnosis. We examined the temporal relationship between DM and prostate cancer risk exploring the period of greatest risk starting from the prediabetic to the post-diabetic period using clinical and administrative data to accurately define the date of DM diagnosis.

METHODS

We identified 5,813 men who developed DM between January 1, 1995 and December 31, 2009 (reference date, date of DM onset or matched date for non-diabetic cohort) and 28,019 non-diabetic men matched by age, smoking history, residence, and reference date. Prostate cancer incidence before and after the reference date was assessed using Cox regression modeling adjusted for matching variables, body mass index, insurance status, and comorbidities. Primary outcomes included hazard ratio (HR) and number needed to be exposed to DM for one additional person to be harmed (NNEH) or benefit (NNEB) with respect to prostate cancer risk.

RESULTS

After full adjustment, the HR for prostate cancer before DM diagnosis was 0.96 (95% CI 0.85-1.08; P=0.4752), and the NNEB was 974 at DM diagnosis. After the reference date, the fully-adjusted HR for prostate cancer in diabetic men was 0.84 (95% CI 0.72-0.97, P=0.0167), and the NNEB 3 years after DM onset was 425. The NNEB continued to decrease over time, reaching 63 at 15 years after DM onset, suggesting an increasing protective effect of DM on prostate cancer risk over time. No significant difference between the diabetic and non-diabetic cohort was found prior to reference date.

CONCLUSION

Prostate cancer risk is not reduced in pre-diabetic men but decreases after DM diagnosis and the protective effect of DM onset on prostate cancer risk increases with DM duration.

Metabolic dysregulation of the insulin-glucose axis and risk of obesity-related cancers in the Framingham heart study-offspring cohort (1971-2008)

BACKGROUND

Obesity-related dysregulation of the insulin-glucose axis is hypothesized in carcinogenesis. We studied impaired fasting glucose (IFG) and other markers of insulin-glucose metabolism in the Framingham Heart Study-Offspring Cohort, which uniquely tracks these markers and cancer >37 years.

METHODS

Participants were recruited between 1971 and 1975 and followed until 2008 (n = 4,615; mean age 66.8 years in 2008). Serum glucose, insulin, and hemoglobin A1c were determined from fasting blood in quart-annual exams. Lifestyle and demographic information was self-reported. HRs and 95% confidence intervals (CI) of cancer risk were computed using time-dependent survival analysis (SASv9.3), while accounting for temporal changes for relevant variables.

RESULTS

We identified 787 obesity-related cancers, including 136 colorectal, 217 breast, and 219 prostate cancers. Absence versus presence of IFG 10 to 20 years and 20+ years before the event or last follow-up was associated with 44% (95% CI, 1.15-1.79) and 57% (95% CI, 1.17-2.11) increased risk of obesity-related cancers, respectively. When time-dependent variables were used, after adjusting for age, sex, smoking, alcohol, and body mass index, IFG was associated with a 27% increased risk of obesity-related cancer (HR = 1.27; CI, 1.1-1.5). Associations were stronger in smokers (HR = 1.41; CI, 1.13-1.76). Increased risk was noted among persons with higher insulin (HR = 1.47; CI, 1.15-1.88) and hemoglobin A1c (HR = 1.54; CI, 1.13-2.10) for the highest (≥ 5.73%) versus lowest (≤ 5.25%) category. A >2-fold increase in colorectal cancer risk was observed for all blood biomarkers of insulin-glucose metabolism, particularly with earlier IFG exposure. Nonsignificant increased risk of breast and prostate cancer was observed for blood biomarkers.

CONCLUSIONS

Earlier IFG exposure (>10 years before) increased obesity-related cancer risk, particularly for colorectal cancer.

IMPACT

Our study explicitly recognizes the importance of prolonged IFG exposure in identifying links between glucose dysregulation and obesity-related cancers.

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.

New players for advanced prostate cancer and the rationalisation of insulin-sensitising medication

Obesity and type 2 diabetes are recognised risk factors for the development of some cancers and, increasingly, predict more aggressive disease, treatment failure, and cancer-specific mortality. Many factors may contribute to this clinical observation. Hyperinsulinaemia, dyslipidaemia, hypoxia, ER stress, and inflammation associated with expanded adipose tissue are thought to be among the main culprits driving malignant growth and cancer advancement. This observation has led to the proposal of the potential utility of "old players" for the treatment of type 2 diabetes and metabolic syndrome as new cancer adjuvant therapeutics. Androgen-regulated pathways drive proliferation, differentiation, and survival of benign and malignant prostate tissue. Androgen deprivation therapy (ADT) exploits this dependence to systemically treat advanced prostate cancer resulting in anticancer response and improvement of cancer symptoms. However, the initial therapeutic response from ADT eventually progresses to castrate resistant prostate cancer (CRPC) which is currently incurable. ADT rapidly induces hyperinsulinaemia which is associated with more rapid treatment failure. We discuss current observations of cancer in the context of obesity, diabetes, and insulin-lowering medication. We provide an update on current treatments for advanced prostate cancer and discuss whether metabolic dysfunction, developed during ADT, provides a unique therapeutic window for rapid translation of insulin-sensitising medication as combination therapy with antiandrogen targeting agents for the management of advanced prostate cancer.

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.

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.

Increased risk of cancer in patients with type 2 diabetes mellitus: a retrospective cohort study in China

Background

Previous studies indicated that type 2 diabetes mellitus (T2DM) might be associated with the risk of cancer. The aim of this study was to investigate the association between T2DM and the risk of developing common cancers in a Chinese population.

Methods

A population-based retrospective cohort study was carried out in the Nan-Hu district of Jiaxing city, Zhejiang province, China. The incidence of cancer cases among type 2 diabetic patients were identified through record-linkage of the Diabetic Surveillance and Registry Database with the Cancer Database from January 2002 to June 2008. The standardized incidence ratio (SIR) and 95% confidence interval (CI) were estimated for the risk of cancer among the patients with type 2 diabetes.

Results

The overall incidence of cancer was 1083.6 per 10⁵ subjects in male T2DM patients and 870.2 per 10⁵ in females. Increased risk of developing cancer was found in both male and female T2DM patients with an SIR of 1.331 (95% CI = 1.143-1.518) and 1.737 (1.478-1.997), respectively. As for cancer subtypes, both male and female T2DM patients had a significantly increased risk of pancreatic cancer with the SIRs of 2.973 (1.73-4.21) and 2.687 (1.445-3.928), respectively. Elevated risk of liver and kidney cancers was only found in male T2DM patients with SIRs of 1.538 (1.005-2.072) and 4.091 (1.418-6.764), respectively. Increased risks of developing breast cancer [2.209 (1.487-2.93)] and leukemia SIR: [4.167 (1.584- 6.749) ] were found in female patients.

Conclusions

These findings indicated that patients with T2DM have an increased risk of developing cancer. Additional cancer screening should be employed in the management of patients with T2DM.

Evolution of insulin development: focus on key parameters

INTRODUCTION

Although insulin products and treatment strategies have improved significantly, clinical challenges still exist. Meeting glycemic goals while minimizing glucose variability and hypoglycemia is of utmost importance when considering existing insulin therapies and designing investigational insulin treatments.

METHODS

A PubMed search identified relevant, peer-reviewed articles related to the evolution of insulin development for this nonsystematic review. Search terms included "animal insulin," "synthetic insulin," "regular human insulin," "insulin lispro," "insulin aspart," "insulin glulisine," "insulin glargine," "insulin detemir," "insulin degludec," "biphasic human insulin," "insulin premixes," "ultra-long acting," "oral insulin," and "inhaled insulin."

RESULTS

While the discovery of animal insulin significantly decreased mortality rates from diabetes, issues with availability and large variability between batches led to difficulty in determining proper doses and, subsequently, challenges in achieving glycemic control and avoiding hypoglycemia. The development of synthetic insulin created a more readily available supply, but hypoglycemia still persisted. Recombinant DNA technology solved insulin production problems and allowed for the development of better retarding agents, but pharmacokinetic/pharmacodynamic profiles still did not mimic natural insulin. Insulin premixes offered improved glycemic control, decreased intrapatient variability versus self-mixing, and required fewer injections per day; however, patient adherence remained a problem due to the need to inject 30-60 minutes before a meal for optimal control. This prompted the development of rapid-acting insulin analogs that could be injected right before a meal and long-acting insulin analogs with flatter time-action profiles.

CONCLUSION

Despite advances in insulin development, a need to provide more physiologic basal insulin coverage and reduce hypoglycemic risk in patients with diabetes remains. Newer insulin analogs and more convenient routes of insulin delivery have shown promising safety and efficacy results. Many patients with diabetes have not reached glycemic goals on currently available insulins. Additional studies are necessary to tailor optimal insulin delivery strategies to specific subsets of diabetes patients.

Diabetes and cancer I: risk, survival, and implications for screening

Type 2 diabetes mellitus (DM) and cancer are common diseases that are frequently diagnosed in the same individual. An association between the two conditions has long been postulated. Here, we review the epidemiological evidence for increased risk of cancer, decreased cancer survival, and decreased rates of cancer screening in diabetic patients. The risk for several cancers, including cancers of the pancreas, liver, colorectum, breast, urinary tract, and endometrium, is increased in patients with DM. In a pooled risk analysis weighting published meta-analytic relative risk (RR) for individual cancer by differences in their incidence rates, we found a population RR of 0.97 (95 % CI, 0.75-1.25) in men and 1.29 (95 % CI, 1.16-1.44) in women. All meta-analyses showed an increased relative risk for cancer in diabetic men, except studies of prostate cancer, in which a protective effect was observed. The relationship between diabetes and cancer appears to be complex, and at present, a clear temporal relationship between the two conditions cannot be defined. DM also impacts negatively on cancer-related survival outcomes and cancer screening rates. The overwhelming evidence for lower cancer screening rates, increased incidence of certain cancers, and poorer prognosis after cancer diagnosis in diabetic patients dictates a need for improved cancer care in diabetic individuals through improved screening measures, development of risk assessment tools, and consideration of cancer prevention strategies in diabetic patients. Part two of this review focuses on the biological and pharmacological mechanisms that may account for the association between DM and cancer.

The Interactions between Insulin and Androgens in Progression to Castrate-Resistant Prostate Cancer

An association between the metabolic syndrome and reduced testosterone levels has been identified, and a specific inverse relationship between insulin and testosterone levels suggests that an important metabolic crosstalk exists between these two hormonal axes; however, the mechanisms by which insulin and androgens may be reciprocally regulated are not well described. Androgen-dependant gene pathways regulate the growth and maintenance of both normal and malignant prostate tissue, and androgen-deprivation therapy (ADT) in patients exploits this dependence when used to treat recurrent and metastatic prostate cancer resulting in tumour regression. A major systemic side effect of ADT includes induction of key features of the metabolic syndrome and the consistent feature of hyperinsulinaemia. Recent studies have specifically identified a correlation between elevated insulin and high-grade PCa and more rapid progression to castrate resistant disease. This paper examines the relationship between insulin and androgens in the context of prostate cancer progression. Prostate cancer patients present a promising cohort for the exploration of insulin stabilising agents as adjunct treatments for hormone deprivation or enhancers of chemosensitivity for treatment of advanced prostate cancer.

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.

Cancer Risk and Behavioral Factors, Comorbidities, and Functional Status in the US Elderly Population

About 80% of all cancers are diagnosed in the elderly and up to 75% of cancers are associated with behavioral factors. An approach to estimate the contribution of various measurable factors, including behavior/lifestyle, to cancer risk in the US elderly population is presented. The nationally representative National Long-Term Care Survey (NLTCS) data were used for measuring functional status and behavioral factors in the US elderly population (65+), and Medicare Claims files linked to each person from the NLTCS were used for estimating cancer incidence. The associations (i.e., relative risks) of selected factors with risks of breast, prostate, lung and colon cancers were evaluated and discussed. Behavioral risk factors significantly affected cancer risks in the US elderly. The most influential of potentially preventable risk factors can be detected with this approach using NLTCS-Medicare linked dataset and for further deeper analyses employing other datasets with detailed risk factors description.

Diabetes and risk of tumors: oncologic considerations

Type 2 diabetes mellitus and malignant tumors are frequent diseases worldwide. The incidence of these two diseases is growing continuously and causes serious health care problem. Population based epidemiologic studies show that the coexistence of type 2 diabetes and malignant tumors is more frequent than expected by the age-corrected incidence and prevalence of each disease. Epidemiologic studies and meta-analyses show that type 2 diabetes increases the risk and tumor specific mortality of certain cancers. The overlapping risk factors of the diseases suggest a relationship between type 2 diabetes and malignant tumors, with a significant role of obesity as a major risk factor. In the pathophysiology of type 2 diabetes there are several biological processes, which may explain the higher cancer risk in type 2 diabetes. In vitro experiments, and in vivo animal studies show that the mitotic effect of hyperinsulinemia plays an important role in the relationship of cancer and type 2 diabetes mellitus. Recent studies show that the different treatment modalities, antidiabetic drugs and their combinations used for the treatment of type 2 diabetes can modify cancer risk. The majority of the data show that metformin therapy decreases, while insulin secretagog drugs slightly increase the risk of certain types of cancers in type 2 diabetes. Metformin can decrease cell proliferation and induce apoptosis in certain cancer cell lines. Endogenous and exogenous (therapy induced) hyperinsulinemia may be mitogenic and may increase the risk of cancer in type 2 diabetes. Human studies showed that the analogue insulin glargin increases the risk of certain cancers. As a result of conceptual weaknesses in study design, data collection, and statistical methods the results of these studies are questionable. According to present knowledge, obtaining and maintaining optimal metabolic target values with the appropriate choice of treatment modality is the aim of treatment in type 2 diabetes. Presently, study results showing elevated mitogenic potential with some antidiabetic treatment modalities are not taken into account, when considering the choice of antidiabetic treatment in type 2 diabetic patients. In the care of patients with increased cancer risk, oncologic considerations should be taken into account. Well designed, prospective, clinical studies would be necessary to demonstrate the possible correlation between treatment modalities of type 2 diabetes and change of cancer risk in type 2 diabetes mellitus. Orv. Hetil., 2011, 152, 1144–1155.

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.

Prostate cancer risk in the Swedish AMORIS study: the interplay among triglycerides, total cholesterol, and glucose

BACKGROUND

In a cohort including 5112 prostate cancer (pCa) patients, the authors investigated associations among triglycerides (TG), total cholesterol (TC), and pCa while taking into account glucose.

METHODS

A cohort (n = 200,660) based on 4 groups of men, according to age at cohort entry, with TG, TC, and glucose measurements was selected from the Apolipoprotein MOrtality RISk (AMORIS) database. Of these, 5112 men developed pCa. Multivariate Cox proportional hazard models were used to analyze associations among TG, TC, and pCa. Competing risks were assessed graphically.

RESULTS

Age-stratified analyses for quartiles of TG, TC, and glucose showed a negative association between glucose and pCa risk (HR, 0.93; 95% CI, 0.86-1.01), 0.93 (0.86-1.01), 0.87 (0.81-0.94) for the second, third, and fourth quartiles compared with the first (P(trend) = .001). Stratified analysis by glucose levels (<6.11 or ≥ 6.11 mmol/L) showed a positive association between hypertriglyceridemia (TG ≥ 1.71 mmol/L) and pCa risk, when there were high glucose levels (HR, 1.23; 95% CI, 1.01-1.48). No association was found for hypercholesterolemia (TC ≥ 6.50 mmol/L). Competing risk analysis showed that protective effects of glucose were overestimated in conventional Cox proportional hazard models and strengthened positive findings between TG and pCa risk.

CONCLUSIONS

The authors'; findings supported the hypothesis that factors of the glucose and lipid metabolism influence pCa risk. Competing risk assessment showed that it is important to take into account the long natural history and age distribution of pCa when interpreting results. The authors'; findings indicate another reason to fight the increasing prevalence of obesity and dyslipidemia.

Glycemic control and prostate cancer progression: results from the SEARCH database

PURPOSE

Several studies have examined the association between diabetes mellitus (DM) and prostate cancer (PCa) risk and progression, however nearly all of these studies have compared diabetic versus non-diabetic men. We sought to investigate the role of glycemic control, as measured by HbA1c, on PCa aggressiveness and prognosis in men with DM and PCa from the Shared Equal Access Regional Cancer Hospital (SEARCH) database.

METHODS

We identified 247 men in SEARCH with DM and a recorded HbA1c value within the 12 months prior to radical prostatectomy between 1988 and 2009. We divided these men into tertiles by HbA1c level. The associations between HbA1c tertiles and risk of adverse pathology and biochemical recurrence were tested using multivariate logistic regression and Cox proportional hazards models, respectively.

RESULTS

Median HbA1c level was 6.9. On multivariate analysis, HbA1c tertiles were predictive of pathological Gleason score (P-trend = 0.001). Relative to the first tertile, men in the second (OR 4.68, P = 0.003) and third tertile (OR 6.60, P < 0.001) were more likely to have Gleason score > or = 4 + 3. HbA1c tertiles were not associated with margin status, node status, extracapsular extension or seminal vesicle invasion (all P-trend > 0.2). In the multivariate Cox proportional hazards model, increasing HbA1c tertiles were not significantly related to risk of biochemical recurrence (P-trend = 0.56).

CONCLUSION

Men with higher HbA1c levels presented with more biologically aggressive prostate tumors at radical prostatectomy. Although risk of recurrence was unrelated to HbA1c levels, further studies are needed to better explore the importance of glycemic control on long-term outcomes in diabetic men with PCa.

Low-carbohydrate diets and prostate cancer: how low is "low enough"?

Previous studies indicate that carbohydrate intake influences prostate cancer biology, as mice fed a no-carbohydrate ketogenic diet (NCKD) had significantly smaller xenograft tumors and longer survival than mice fed a Western diet. As it is nearly impossible for humans to consume and maintain NCKD, we determined whether diets containing 10% or 20% carbohydrate kcal showed similar tumor growth as NCKD. A total of 150 male severe combined immunodeficient mice were fed a Western diet ad libitum, injected with the human prostate cancer cell line LAPC-4, and then randomized 2 weeks later to one of three arms: NCKD, 10% carbohydrate, or 20% carbohydrate diets. Ten mice not injected were fed an ad libitum low-fat diet (12% fat kcal) serving as the reference in a modified-paired feeding protocol. Mice were sacrificed when tumors reached 1,000 mm(3). Despite consuming extra calories, all mice receiving low-carbohydrate diets were significantly lighter than those receiving a low-fat diet (P < 0.04). Among the low-carbohydrate arms, NCKD-fed mice were significantly lighter than the 10% or 20% carbohydrate groups (P < 0.05). Tumors were significantly larger in the 10% carbohydrate group on days 52 and 59 (P < 0.05), but at no other point during the study. Diet did not affect survival (P = 0.34). There were no differences in serum insulin-like growth factor-I or insulin-like growth factor binding protein-3 at sacrifice among the low-carbohydrate arms (P = 0.07 and P = 0.55, respectively). Insulin was significantly lower in the 20% carbohydrate arm (P = 0.03). LAPC-4 xenograft mice fed a low-carbohydrate diet (10-20% carbohydrate kcal) had similar survival as mice consuming NCKD (0% carbohydrate kcal).

HNF1B and JAZF1 genes, diabetes, and prostate cancer risk

BACKGROUND

Epidemiologic studies have shown that men with type II diabetes have a lower risk of prostate cancer than non-diabetic men. Recently, common variants in two genes, HNF1B and JAZF1, were found to be associated with both of these diseases.

METHODS

We examined whether the relationship between HNF1B and JAZF1 variants and decreased prostate cancer risk may potentially be mediated through diabetes in two large prospective studies, the Cancer Prevention Study II Nutrition Cohort and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.

RESULTS

Three HNF1B SNPS, rs11649743, rs4430796, and rs7501939, were associated with decreased risk of prostate cancer and were also associated, with marginal statistical significance, with increased risk of diabetes. The JAZF1 SNPs rs6968704 and rs10486567 were associated with decreased risk of prostate cancer but were not associated with diabetes. All five SNP-prostate cancer relationships did not substantially differ when the analyses were stratified by diabetic status or when diabetic status was controlled for in the model. Furthermore, the association of diabetes with prostate cancer was not altered when the SNPs were included in the logistic model.

CONCLUSIONS

These findings indicate that the HNF1B variants are directly associated with both diabetes and prostate cancer, that diabetes does not mediate these gene variant-prostate cancer relationships, and the relationship between these diseases is not mediated through these gene variants.

Inference of combinatorial Boolean rules of synergistic gene sets from cancer microarray datasets

MOTIVATION

Gene set analysis has become an important tool for the functional interpretation of high-throughput gene expression datasets. Moreover, pattern analyses based on inferred gene set activities of individual samples have shown the ability to identify more robust disease signatures than individual gene-based pattern analyses. Although a number of approaches have been proposed for gene set-based pattern analysis, the combinatorial influence of deregulated gene sets on disease phenotype classification has not been studied sufficiently.

RESULTS

We propose a new approach for inferring combinatorial Boolean rules of gene sets for a better understanding of cancer transcriptome and cancer classification. To reduce the search space of the possible Boolean rules, we identify small groups of gene sets that synergistically contribute to the classification of samples into their corresponding phenotypic groups (such as normal and cancer). We then measure the significance of the candidate Boolean rules derived from each group of gene sets; the level of significance is based on the class entropy of the samples selected in accordance with the rules. By applying the present approach to publicly available prostate cancer datasets, we identified 72 significant Boolean rules. Finally, we discuss several identified Boolean rules, such as the rule of glutathione metabolism (down) and prostaglandin synthesis regulation (down), which are consistent with known prostate cancer biology.

AVAILABILITY

Scripts written in Python and R are available at http://biosoft.kaist.ac.kr/~ihpark/. The refined gene sets and the full list of the identified Boolean rules are provided in the Supplementary Material.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Genetic susceptibility to type 2 diabetes is associated with reduced prostate cancer risk

OBJECTIVE

To examine the collective effects of type 1 (T1D) and type 2 diabetes (T2D) risk alleles on prostate cancer (PCa) risk.

METHODS

Using data on 14 and 18 single nucleotide polymorphisms (SNPs) that effect T1D and T2D risk, respectively, we generated risk scores (a 'risk allele count' and a 'genetic relative risk') for both T1D and T2D for 1,171 non-Hispanic white, PSA-screened PCa cases and 1,101 matched controls from the Cancer Genetic Markers of Susceptibility study. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for associations between the diabetes risk scores and PCa risk.

RESULTS

Both T2D risk scores, but neither T1D score, showed an inverse association with PCa (p < 0.01). These associations remained significant after excluding HNF1B SNP rs4430796 (a known PCa risk factor) from the analysis. The highest quartile of the T2D allele count (>20 risk alleles) was associated with reduced PCa risk (OR = 0.77; CI: 0.60-0.99) compared to the lowest category (<17 risk alleles).

CONCLUSIONS

These results suggest that individuals with increased genetic susceptibility to T2D have decreased risk for PCa. This association is consistent with the observation that individuals with T2D are at decreased risk for PCa; however, data on T2D status was not available for this analysis.

Association of exogenous insulin or sulphonylurea treatment with an increased incidence of hepatoma in patients with hepatitis C virus infection

BACKGROUND

Diabetes mellitus is frequently seen in hepatitis C patients and is often treated with antidiabetic agents that increase serum insulin levels. Because insulin is a growth-promoting hormone, antidiabetic agents could pose a risk for hepatocellular carcinoma (HCC).

AIM

The aim of this study was to investigate an association between antidiabetic therapies and the incidence of HCC in hepatitis C patients with diabetes mellitus.

METHODS

A nested case-control study was conducted. Participants were recruited from a cohort study, in which patients with hepatitis C were consecutively registered. Participants were assigned to an HCC group (n=138) or a non-HCC group (n=103). To identify independent factors, variables including use of antidiabetic agents were analysed by logistic regression analysis.

RESULTS

Besides ageing, being male, cirrhosis and hypoalbuminaemia, use of exogenous insulin and a second-generation sulphonylurea were significant independent factors associated with an incidence of HCC [odds ratio (OR) 2.969, 95% confidence interval (CI) 1.293-6.819, P<0.0103 and OR 6.831, 95% CI 1.954-23.881, P<0.0026 respectively). In stratified analyses, the impact of these antidiabetic agents was more evident in patients who were non-cirrhotic than in those who were cirrhotic.

CONCLUSIONS

Exogenous insulin and a second-generation sulphonylurea were independent variables associated with an incidence of HCC in hepatitis C patients with diabetes mellitus. This association was evident in patients who were non-cirrhotic. To verify a causal relationship between these antidiabetic agents and the development of HCC, a prospective cohort study is required.

The protective effect of diabetes mellitus against prostate cancer: role of sex hormones

BACKGROUND

Diabetes mellitus (DM) has been associated with decreased risk of prostate cancer (PC) in several reports. Hormonal environment of diabetic patients is believed to be an important contributing factor in this regard.

METHODS

Using data from a multi-center case-control study in Iran, base line testosterone, sex hormone binding globulin (SHBG), estradiol, and albumin levels as well as thorough demographic and medical characteristics of 194 newly diagnosed prostate cancer patients were determined. There were 317 ethnicity-matched men with no cancer as controls as well. Data was analyzed for hormones of interest in DM patients regarding their cancer status.

RESULTS

Of 511 enrolled patients, twenty-one cases and 63 controls were diagnosed as DM. Patients with DM were significantly less likely to have PC (OR: 0.44, P = 0.003). Time since DM diagnosis was also inversely correlated with the risk of cancer (P trend < 0.0001). Control patients had significantly higher testosterone, estradiol, and testosterone/SHBG ratio (P < 0.05). As time since DM diagnosis increased by quartiles, testosterone significantly increased (P trend < 0.05). The risk of PC also significantly declined (P trend < 0.0001) following an initial remarkable increase early after DM diagnosis. After including the hormones in the logistic regression model, there was a weak, yet significant inverse association of testosterone/SHBG and DM duration with the risk of PC.

CONCLUSIONS

Based on our results DM duration is inversely correlated with the risk of prostate cancer. Our results do not support the hypothesis that sex hormones, including testosterone, play a major role in the protective effect of DM against PC.

Type 2 diabetes mellitus associated with increased risk for colorectal cancer: evidence from an international ecological study and population-based risk analysis in China

OBJECTIVE

To study the association between type 2 diabetes mellitus (T2DM) and colorectal cancer (CRC).

STUDY DESIGN

An international ecological study and a population-based risk analysis.

METHODS

Prevalence data for T2DM and incidence data for CRC were collected from 170 countries, and Spearman's correlation was calculated between T2DM and CRC. In the Nan-Hu district of Jia-Xing city, Zhejiang province, China, the incidence of CRC among T2DM patients between 1 January 2002 and 30 June 2002 was identified through record linkage between the Diabetic Surveillance and Registry Database with the Cancer Surveillance and Registry Database. Standardized incidence ratios (SIRs) and 95% confidence intervals were used to estimate the risk of CRC among T2DM patients.

RESULTS

Significant positive correlations (r(s)=0.534 and 0.597 in males and females, respectively) were found between the prevalence of T2DM and the incidence of CRC. Sixty-four cases of CRC were found among 7938 T2DM patients. The SIR for CRC among T2DM patients was 1.588 (95% CI 1.199-1.977). For male T2DM patients, the SIR for CRC was 1.821 (95% CI 1.234-2.408), compared with 1.364 (95% CI 0.85-1.879) among female T2DM patients. Significant increased risks for colon cancer were found, with an SIR of 1.899 (95% CI 1.139-2.658) in male T2DM patients. Female T2DM patients showed a borderline significant risk for colon cancer, with an SIR of 1.687 (95% CI 0.948-2.426). However, no significant associations were found between T2DM and risk for rectal cancer among males (SIR 1.723, 95% CI 0.786-2.66) or females (SIR 0.906, 95% CI 0.235-1.578) (all P>0.05).

CONCLUSIONS

T2DM was associated with increased risk for CRC, and this association was more evident for colon cancer and among male diabetic patients.

Dystroglycan patterns on the prostate of non-obese diabetic mice submitted to glycaemic control

Dystroglycan (DG) is an adhesion protein which plays a crucial role in the maintenance of tissue integrity. Diabetes has been pointed out as a disease which causes harmful effects on prostate function. Therefore, the main objective of this work was to verify DG distribution and structure features in diabetic mice with and without glycaemic control and to relate these parameters to prostate pathogenesis. Thirty mice (Nod and BALB/c) were divided into three groups after 20 days of diabetic state: the control group received a 5 ml/kg dose of physiological saline daily for 20 days; the diabetic group had the same treatment as the control group; the diabetic-insulin group received 4-5 IU doses of Neutral Protamine Hagedorn (NPH) insulin daily for 20 days. After 20 days of treatment, all animals were killed and samples from the ventral prostate were processed for immunological and light microscopy analyses. The results showed diminished beta- and alpha-DG receptors in the diabetic group. However, there was a recovery of both beta-and alpha-DG receptor immunolocalization after insulin administration. Epithelial and stromal morphological changes were verified in the diabetic group, which also presented recovery after insulin treatment. Thus, it could be concluded that diabetes disturbed prostate structure integrity and altered the occurrence of alpha and beta-DG receptors, indicating decreased cell-matrix extracellular and cell-basal membrane attachment. However, insulin treatment could partially restore glandular homeostasis. The decrease in epithelial-stromal interaction certainly predisposes this gland in diabetic mice to be a prostate disease target.

Association of diabetes with prostate cancer risk in the multiethnic cohort

Among men of European ancestry, diabetics have a lower risk of prostate cancer than do nondiabetics. The biologic basis of this association is unknown. The authors have examined whether the association is robust across populations in a population-based prospective study. The analysis included 5,941 prostate cancer cases identified over a 12-year period (1993-2005) among 86,303 European-American, African-American, Latino, Japanese-American, and Native Hawaiian men from the Multiethnic Cohort. The association between diabetes and prostate-specific antigen (PSA) levels (n = 2,874) and PSA screening frequencies (n = 46,970) was also examined. Diabetics had significantly lower risk of prostate cancer than did nondiabetics (relative risk = 0.81, 95% confidence interval (CI): 0.74, 0.87; P < 0.001), with relative risks ranging from 0.65 (95% CI: 0.50, 0.84; P = 0.001) among European Americans to 0.89 (95% CI: 0.77, 1.03; P = 0.13) among African Americans. Mean PSA levels were significantly lower in diabetics than in nondiabetics (mean PSA levels, 1.07 and 1.28, respectively; P = 0.003) as were PSA screening frequencies (44.7% vs. 48.6%; P < 0.001); however, this difference could explain only a small portion ( approximately 20%) of the inverse association between these diseases. Diabetes is a protective factor for prostate cancer across populations, suggesting shared risk factors that influence a common mechanism.

Diabetes mellitus and risk of prostate cancer in the health professionals follow-up study

History of diabetes may be associated with decreased prostate cancer (PCa) risk. Published studies have not always accounted for time since diabetes diagnosis or confounding and effect modification by lifestyle factors. The authors investigated the relationship between diabetes and PCa risk in men in the Health Professionals Follow-Up Study from 1986 to 2004. During that time, 4,511 new PCa cases were identified. Multivariate hazard ratios (HR) were estimated using Cox regression. The HR of PCa comparing men with vs. without diabetes was 0.83 and 95% confidence interval (CI): 0.74, 0.94. PCa risk was not reduced in the first year after diabetes diagnosis (HR: 1.30, CI: 0.97, 1.72), was lower for men diagnosed for 1-6 years (HR: 0.82, CI: 0.66, 1.02), and was even lower for men who had been diagnosed for 6-15 (HR: 0.75, CI: 0.61, 0.93) or >15 years (HR: 0.78, CI: 0.63, 0.96). Reduced PCa risk was stronger in men diagnosed before 1994 (pre-PSA era) vs. after 1994. The authors also demonstrated that obese and diabetic men had a lower HR for PCa than those who were either not obese and diabetic or obese and non-diabetic. Results are consistent with the hypothesis that diabetes is associated with reduced PCa risk. Potential biological mechanisms are discussed.