History of diabetes mellitus and subsequent prostate cancer risk in the NIH-AARP Diet and Health Study

Quantifying the Contributions of Environmental Factors to Prostate Cancer and Detecting Risk-Related Diet Metrics and Racial Disparities

The relevance of nongenetic factors to prostate cancer (PCa) has been elusive. We aimed to quantify the contributions of environmental factors to PCa and identify risk-related diet metrics and relevant racial disparities. We performed a unique analysis of the Diet History Questionnaire data of 41 830 European Americans (EAs) and 1282 African Americans (AAs) in the PLCO project. The independent variables in the regression models consisted of age at trial entry, race, family history of prostate cancer (PCa-fh), diabetes history, body mass index (BMI), lifestyle (smoking and coffee consumption), marital status, and a specific nutrient/food factor (X). P < .05 and a 95% confidence interval excluding zero were adopted as the criteria for determining a significant difference (effect). We established a priority ranking among PCa risk-related genetic and environmental factors according to the deviances explained by them in the multivariate Cox-PH regression analysis: age > PCa-fh > diabetes ⩾ race > lifestyle ⩾marital-status ⩾BMI > X. We confirmed previous studies showing that (1) high protein and saturated fat levels in diet were related to increased PCa risk, (2) high-level supplementary selenium intake was harmful rather than beneficial for preventing PCa, and (3) supplementary vitamin B6 was beneficial for preventing benign PCa. We obtained the following novel findings: high-level organ meat intake was an independent predictor for increased aggressive PCa risk; supplementary iron, copper and magnesium increased benign PCa risk; and the AA diet was "healthy" in terms of the relatively lower protein and fat levels and was "unhealthy" in that it more commonly contained organ meat. In conclusion, we established a priority ranking among the contributing factors for PCa and identified several risk-related diet metrics and the racial disparities. Our findings suggested some new approaches to prevent PCa such as restriction of organ meat intake and supplementary microminerals.

Differences in the relationship between diabetes and prostate cancer among Black and White non-Hispanic men

PURPOSE

Studies finding lower incidence rates of prostate cancer among men with diabetes have been primarily conducted in White non-Hispanic (WNH) populations. The purpose of this analysis is to compare the relationship between diabetes and prostate cancer among Black (BNH) and White non-Hispanic men.

METHODS

We used Surveillance, Epidemiology, and End Results (SEER)-Medicare data from 2011 to 2015 to compare incidence rates and tumor characteristics between BNH and WNH men by diabetes status. Age-adjusted incidence rates and corresponding rate ratios (RR) by diabetes status were calculated overall and by tumor grade, stage, and PSA level separately for BNH and WNH men. We used multivariable logistic regression to compare tumor characteristics among men with prostate cancer in the numerator, both within and across race/ethnic groups.

RESULTS

Overall age-adjusted incidence rates were significantly lower in men with diabetes compared to those without among WNH men [RR = 0.88 95% Confidence Interval (CI) 0.86-0.90] but there was no difference in rates by diabetes status among BNH men (RR = 1.01 95% CI 0.96-1.07). Men with diabetes were less likely to be diagnosed with distant-staged tumors compared to those without diabetes in both race/ethnic groups but the magnitude of difference by diabetes status was greater in BNH [Odds Ratio (OR) = 0.52 95% CI 0.42-0.64] than WNH (OR = 0.88 95% CI 0.81-0.95) men (p-value for interaction < 0.001).

CONCLUSION

The relationship between diabetes and prostate cancer differed between BNH and WNH men. The differences could have implications in evaluating the effectiveness of prostate cancer screening in men with diabetes across racial/ethnic subgroups.

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.

Physical activity in relation to risk of prostate cancer: a systematic review and meta-analysis

Background

Prostate cancer (PCa) is one of the most common cancers among men, yet little is known about its modifiable risk and protective factors. This study aims to quantitatively summarize observational studies relating physical activity (PA) to PCa incidence and mortality.

Materials and methods

Published articles pertaining to PA and PCa incidence and mortality were retrieved in July 2017 using the Medline and EMBASE databases. The literature review yielded 48 cohort studies and 24 case-control studies with a total of 151 748 PCa cases. The mean age of the study participants at baseline was 61 years.

Results

In random-effects models, comparing the highest versus the lowest level of overall PA showed a summary relative risk (RR) estimate for total PCa incidence close to the null [RR = 0.99, 95% confidence interval (CI) = 0.94-1.04]. The corresponding RRs for advanced and non-advanced PCa were 0.92 (95% CI = 0.80-1.06) and 0.95 (95% CI = 0.85-1.07), respectively. We noted a statistically significant inverse association between long-term occupational activity and total PCa (RR = 0.83, 95% CI = 0.71-0.98, n studies = 13), although that finding became statistically non-significant when individual studies were removed from the analysis. When evaluated by cancer subtype, an inverse association with long-term occupational activity was noted for non-advanced/non-aggressive PCa (RR = 0.51, 95% CI = 0.37-0.71, n studies = 2) and regular recreational activity was inversely related to advanced/aggressive PCa (RR = 0.75, 95% CI = 0.60-0.95, n studies = 2), although these observations are based on a low number of studies. Moreover, PA after diagnosis was related to reduced risk of PCa mortality among survivors of PCa (summary RR based on four studies = 0.69, 95% CI = 0.55-0.85).

Conclusions

Whether PA protects against PCa remains elusive. Further investigation taking into account the complex clinical and pathologic nature of PCa is needed to clarify the PA and PCa incidence relation. Moreover, future studies are needed to confirm whether PA after diagnosis reduces risk of PCa mortality.

Epidemiology of Prostate Cancer

Prostate cancer is the second most frequent cancer diagnosis made in men and the fifth leading cause of death worldwide. Prostate cancer may be asymptomatic at the early stage and often has an indolent course that may require only active surveillance. Based on GLOBOCAN 2018 estimates, 1,276,106 new cases of prostate cancer were reported worldwide in 2018, with higher prevalence in the developed countries. Differences in the incidence rates worldwide reflect differences in the use of diagnostic testing. Prostate cancer incidence and mortality rates are strongly related to the age with the highest incidence being seen in elderly men (> 65 years of age). African-American men have the highest incidence rates and more aggressive type of prostate cancer compared to White men. There is no evidence yet on how to prevent prostate cancer; however, it is possible to lower the risk by limiting high-fat foods, increasing the intake of vegetables and fruits and performing more exercise. Screening is highly recommended at age 45 for men with familial history and African-American men. Up-to-date statistics on prostate cancer occurrence and outcomes along with a better understanding of the etiology and causative risk factors are essential for the primary prevention of this disease.

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.

Lifestyle and Dietary Factors and Prostate Cancer Risk: A Multicentre Case-Control Study

This study aims to explore the association between fruit and vegetable intake, high fat, body mass index (BMI) score, physical activity, and the occurrence of prostate cancer among Jordanian men. A case-control study was conducted in three large referral hospitals. The sample included 165 prostate cancer patients in the case group and 177 healthy participants in the control group. The results showed that smoking (odds ratio [OR] = 0.32; 95% confidence interval [CI] = [0.18, 0.57]), a history of prostate infection (OR = 0.21; 95% CI = [0.11, 0.38]), high-fat intake (OR = 0.44; 95% CI = [0.23, 0.85]), and increased mean of BMI (OR = 1.08; 95% CI = [1.02, 1.13]) increased the likelihood of developing prostate cancer. Healthy diet and giving up smoking are recommended, as they may contribute to a reduction in the incidence of prostate cancer. More randomized clinical trials in this area are needed to strengthen the available evidence and reduce the effects of confounding variables.

Metformin and cancer: An existing drug for cancer prevention and therapy

Metformin is a standard clinical drug used to treat type 2 diabetes mellitus (T2DM) and polycystic ovary syndrome. Recently, epidemiological studies and meta-analyses have revealed that patients with T2DM have a lower incidence of tumor development than healthy controls and that patients diagnosed with cancer have a lower risk of mortality when treated with metformin, demonstrating an association between metformin and tumorigenesis. In vivo and in vitro studies have revealed that metformin has a direct antitumor effect, which may depress tumor proliferation and induce the apoptosis, autophagy and cell cycle arrest of tumor cells. The mechanism underpinning the antitumor effect of metformin has not been well established. Studies have demonstrated that reducing insulin and insulin-like growth factor levels in the peripheral blood circulation may lead to the inhibition of phosphoinositide 3-kinase/Akt/mechanistic target of rapamycin (mTOR) signaling or activation of AMP-activated protein kinase, which inhibits mTOR signaling, a process that may be associated with the antitumor effect of metformin. The present review primarily focuses on the recent progress in understanding the function of metformin in tumor development.

Prospective study of Type 2 diabetes mellitus, anti-diabetic drugs and risk of prostate cancer

Type 2 diabetes mellitus (T2DM) has consistently been associated with decreased risk of prostate cancer; however, if this decrease is related to the use of anti-diabetic drugs is unknown. We prospectively studied men in the comparison cohort in the Prostate Cancer data Base Sweden 3.0, with data on T2DM, use of metformin, sulfonylurea and insulin retrieved from national health care registers and demographic databases. Cox proportional hazards regression models were used to compute hazard ratios (HR) and 95% confidence intervals (CI) of prostate cancer, adjusted for confounders. The study consisted of 612,846 men, mean age 72 years (standard deviation; SD = 9 years), out of whom 25,882 men were diagnosed with prostate cancer during follow up, mean time of 5 years (SD = 3 years). Men with more than 1 year's duration of T2DM had a decreased risk of prostate cancer compared to men without T2DM (HR = 0.85, 95% CI = 0.82-0.88) but among men with T2DM, those on metformin had no decrease (HR = 0.96, 95% CI = 0.77-1.19), whereas men on insulin (89%) or sulfonylurea (11%) had a decreased risk (HR = 0.73, 95% CI = 0.55-0.98), compared to men with T2DM not on anti-diabetic drugs. Men with less than 1 year's duration of T2DM had no decrease in prostate cancer risk (HR = 1.11, 95% CI = 0.95-1.31). Our results gave no support to the hypothesis that metformin protects against prostate cancer as recently proposed. However, our data gave some support to an inverse association between T2DM severity and prostate cancer risk.

Association between baseline serum glucose, triglycerides and total cholesterol, and prostate cancer risk categories

Lifestyle-related risk factors such as hyperglycemia and dyslipidemia have been associated with several cancers. However, studies exploring their link with prostate cancer (PCa) clinicopathological characteristics are sparse and inconclusive. Here, we investigated the associations between serum metabolic markers and PCa clinicopathological characteristics. The study comprised 14,294 men from the Swedish Apolipoprotein MOrtality RISk (AMORIS) cohort who were diagnosed with PCa between 1996 and 2011. Univariate and multivariable logistic regression were used to investigate the relation between glucose, triglycerides and total cholesterol and PCa risk categories, PSA, Gleason score, and T-stage. Mean age at time of PCa diagnosis was 69 years. Men with glucose levels >6.9 mmol/L tend to have PSA<4 μg/L, while those with glucose levels of 5.6-6.9 mmol/L had a greater odds of PSA>20 μg/L compared to PSA 4.0-9.9 μg/L. Hypertriglyceridemia was also positively associated with PSA>20 μg/L. Hyperglycemic men had a greater odds of intermediate- and high-grade PCa and advanced stage or metastatic PCa. Similarly, hypertriglyceridemia was positively associated with high-grade PCa. There was also a trend toward an increased odds of intermediate risk localized PCa and advanced stage PCa among men with hypertriglyceridemia. Total cholesterol did not have any statistically significant association with any of the outcomes studied. Our findings suggest that high serum levels of glucose and triglycerides may influence PCa aggressiveness and severity. Further investigation on the role of markers of glucose and lipid metabolism in influencing PCa aggressiveness and severity is needed as this may help define important targets for intervention.

The impact of nutrition in urogenital cancers

Prostate, bladder and kidney cancers remain the most common cancers of the urinary tract. Despite improved primary prevention, detection and treatment, the incidence of age-related cancers of the urinary tract is likely to rise as a result of global population ageing. An association of diet with prostate, bladder and kidney carcinogenesis is plausible since the majority of metabolites, including carcinogens, are excreted through the urinary tract. Moreover, large regional differences in incidence rates of urologic tumours exist throughout the world. These rates change when people relocate to different geographic areas, which is suggestive of a strong environmental influence. As a result of these observations, numerous studies have been conducted to assess the effects of diet and nutritional status in kidney, bladder and prostate carcinogenesis. Here, we review the literature assessing the effect of diet and nutritional status on urological cancer risk, which has attracted the most interest.

Diabetes mellitus and risk of prostate cancer in the European Prospective Investigation into Cancer and Nutrition

The current epidemiologic evidence suggests that men with type 2 diabetes mellitus may be at lower risk of developing prostate cancer, but little is known about its association with stage and grade of the disease. The association between self-reported diabetes mellitus at recruitment and risk of prostate cancer was examined in the European Prospective Investigation into Cancer and Nutrition (EPIC). Among 139,131 eligible men, 4,531 were diagnosed with prostate cancer over an average follow-up of 12 years. Multivariable hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards models stratified by EPIC-participating center and age at recruitment, and adjusted for education, smoking status, body mass index, waist circumference, and physical activity. In a subset of men without prostate cancer, the cross-sectional association between circulating concentrations of androgens and insulin-like growth factor proteins with diabetes status was also investigated using linear regression models. Compared to men with no diabetes, men with diabetes had a 26% lower risk of prostate cancer (HR, 0.74; 95% CI, 0.63-0.86). There was no evidence that the association differed by stage (p-heterogeneity, 0.19) or grade (p-heterogeneity, 0.48) of the disease, although the numbers were small in some disease subgroups. In a subset of 626 men with hormone measurements, circulating concentrations of androstenedione, total testosterone and insulin-like growth factor binding protein-three were lower in men with diabetes compared to men without diabetes. This large European study has confirmed an inverse association between self-reported diabetes mellitus and subsequent risk of prostate cancer.

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.

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.

Gender-specific effects of oral hypoglycaemic agents on cancer risk in type 2 diabetes mellitus

AIMS

To analyse the association between cancer incidence and oral diabetes therapy (biguanide, sulphonylurea, thiazolidinedione and meglitinide) in men and women with type 2 diabetes mellitus.

METHODS

A retrospective analysis of the electronic health record-based Cleveland Clinic Diabetes Registry (25 613 patients) was cross-indexed with the histology-based tumour registry (48 051 cancer occurrences) over an 8-year period (1998-2006). Multiple imputations were used to account for missing data. Cox regression with propensity scores was used to model time for the development of incident cancer in each of the imputed datasets and the results were pooled.

RESULTS

During 51 994 person follow-up years, 892 incident cancer cases were identified; prostate (14.5%) and breast (11.7%) malignancies were most frequent. In women, thiazolidinedione use was associated with a 32% decreased cancer risk compared with sulphonylurea use [hazard ratio (HR) 0.68; 95% confidence interval (CI) 0.48-0.97, in the adjusted analysis]. Comparison of insulin secretagogues (sulphonylurea and meglitinide) versus insulin sensitizers (biguanide and thiazolidinedione) demonstrated a 21% decreased cancer risk in insulin sensitizers [HR 0.79 (95% CI 0.64-0.98) in the adjusted analysis]. Oral diabetes therapy showed no significant difference in men. Adjustments were made for age, body mass index (BMI), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides, coronary heart disease (CHD), diabetes oral monotherapy, race, gender, haemoglobin A1c, statin use, income, insulin use, glomerular filtration rate (GFR), new diabetes status, prior cancer, prior cerebrovascular accident (stroke or transient ischaemic event), systolic/diastolic blood pressure, tobacco use (ever/never) and the propensity score for receiving a biguanide.

CONCLUSIONS

Oral insulin sensitizers, particularly thiazolidinedione, are associated with decreased malignancy risk in women with type 2 diabetes mellitus.

Observational follow-up of the PROactive study: a 6-year update

AIMS

The PROactive study investigated pioglitazone for secondary prevention of macrovascular events in type 2 diabetes mellitus. Pioglitazone showed a 10% (non-significant) relative risk (RR) reduction for the primary composite endpoint and a significant 16% reduction for the main secondary endpoint (death, myocardial infarction, stroke) after a mean 34.5 months. There was no difference in cumulative malignancy incidence, but an imbalance in bladder malignancies (pioglitazone 14, placebo 5). We present a pre-specified 6-year interim analysis of a 10-year observational follow-up.

METHODS

Any patient completing PROactive was eligible. No study treatments were provided. A Cox proportional hazard model compared non-adjudicated macrovascular events (same endpoints as PROactive excluding acute coronary syndrome) based on original randomization. Malignancies were compared using conventional RR ratios.

RESULTS

Of 5238 randomized patients, 3599 (74%) entered the follow-up. For the follow-up (mean 5.8 years) or combined double-blind and follow-up periods (≤9.5 years, mean 8.7), there were no statistically significant differences in primary or main secondary endpoints. For the combined period, a similar percentage of patients had any diagnosed malignancy (RR = 1.05, 95% CI [0.89, 1.24]) or bladder malignancy (RR = 1.06, 95% CI [0.59, 1.89]) in the pioglitazone and placebo groups. There were fewer cases of bladder malignancy with pioglitazone (15 [0.6%] vs. 19 [0.7%] for placebo) for the combined period when events diagnosed in the first 365 days were excluded, and fewer cases for the follow-up period alone (10 [0.5%] vs. 17 [1.0%] for placebo). Further analyses of pioglitazone use (including use during follow-up) found no significant difference in bladder malignancies between any and no pioglitazone use for the combined period.

CONCLUSIONS

These data suggest that improved macrovascular outcomes seen with pioglitazone subside without continued pioglitazone treatment. The double-blind period bladder cancer imbalance did not persist in follow-up.

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 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.

Diabetes mellitus and prostate cancer risk; a nationwide case-control study within PCBaSe Sweden

BACKGROUND

Diabetes mellitus (DM) increases the risk for cancer at almost all sites, but data on the association with prostate cancer are inconsistent.

METHODS

We assessed the risk of a prostate cancer diagnosis among men with type 2 (T2)DM in a nationwide population-based case-control study including 44,352 men with prostate cancer identified through the Prostate Cancer data Base Sweden (PCBaSe) between 2002 and 2006 and 221,495 age-matched men from the general population.

RESULTS

Overall, the risk of prostate cancer among men with T2DM was lower than among men without T2DM [OR, 0.80; 95% confidence interval (CI), 0.76-0.85]. The risk decreased with longer disease duration and was observed across all tumor risk categories, although most clearly among men with low risk tumors (OR, 0.71; 95% CI, 0.64-0.80). The risk for prostate cancer was reduced among diabetic men on dietary treatment only (OR, 0.89; 95% CI, 0.80-0.99) but more markedly among men on oral hypoglycemic agents (OR, 0.80; 95% CI, 0.74-0.87) and insulin (OR, 0.72; 95% CI, 0.69-0.81). Obese diabetic men (BMI > 30 kg/m(2)) showed a reduced risk (OR, 0.72; 95% CI, 0.65-0.80) compared with men without diabetes. There was a trend of decreasing risk with increasing levels of HbA1c (P < 0.05).

CONCLUSIONS

This nationwide study confirmed a reduced risk of being diagnosed with prostate cancer among men with T2DM, especially for low-risk tumors. An altered hormonal milieu is a plausible explanation, although the possibility of decreased prostate cancer detection among diabetic men cannot be ruled out.

IMPACT

This is the largest study to examine the association between T2DM and prostate cancer accounting for tumor risk group and diabetes treatment.

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.

Risk of esophagus cancer in diabetes mellitus: a population-based case-control study in Taiwan

Background

Diabetes mellitus (DM) has been associated with the cancer risk. This study investigated relationship between DM and esophageal cancer using Taiwan’s insurance data.

Methods

We identified 549 patients with esophageal cancer newly diagnosed in 2000-2009 and randomly selected 2196 controls without any cancer, frequency matched by sex, age and diagnosis year of cases. Logistic regression model estimated odds ratios (ORs) and 95% confidence intervals (CI) of esophageal cancer associated with DM, sex, age. co-morbidities and medications.

Results

Cases were more prevalent than controls for alcoholism and esophageal disorders and using nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclooxygenase-2 inhibitors but not DM. Esophageal cancer had no association with DM (OR 0.99, 95% CI 0.71-1.37), but significantly associated with alcoholism (OR 14.1, 95% CI 7.87-25.4), esophageal ulcer (OR 10.1, 95% CI 5.70-17.9), esophageal reflux (OR 3.47, 95% CI 2.14-5.26) and uses of NSAIDs (OR 2.73, 95% CI 1.80-4.13). An elevated risk of esophageal cancer appeared in DM patients taking insulin (OR 2.57, 95% CI 1.08-6.15) or sulfonyurea (OR 3.80, 95% CI 1.16-12.5).

Conclusions

Patients with DM are not at higher risk for esophagus cancer. However, esophageal disorders and anti-diabetic drugs are associated with the risk of the 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.

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.

Cancer occurrence in Danish diabetic patients: duration and insulin effects

AIMS/HYPOTHESIS

Cancer is more frequent among diabetes patients, but it is unknown how this excess varies with duration of diabetes and insulin use. The aim of this study was to analyse disease data to examine this issue further.

METHODS

We linked the Danish National Diabetes Register and Cancer Registry and performed a cohort analysis of the entire Danish population by diabetes status, duration of diabetes and insulin use, comparing cancer incidence rates in diabetic patients with the non-diabetic population for the 15 year period 1995-2009, using Poisson regression with natural splines to describe the variation by duration.

RESULTS

We found 20,032 cancer cases among patients not using insulin and 2,794 cancer cases among diabetic patients using insulin. The cancer incidence rate ratio among non-insulin users relative to the non-diabetic population decreased from over 2 at diagnosis to 1.15 after 2 years of diabetes duration. The cancer incidence rate ratio was higher among patients using insulin, decreasing from 5 at the start of insulin treatment to about 1.3 [corrected] after 5 years of insulin use. Among non-insulin users, cancers of the stomach, colorectum, liver, pancreas, lung, corpus uteri, kidney and brain, and lymphomas were elevated. Among insulin users the rate ratio of prostate cancer was decreasing by duration whereas we found higher risk of cancer of the stomach, lung, liver, pancreas and kidney. Breast cancer incidence rates were not affected by either diabetes or insulin use.

CONCLUSIONS

The observed duration effects suggest that both increased surveillance for cancer in the first years after diagnosis of diabetes, and reverse causation, where undiagnosed cancers increase the likelihood of diabetes diagnosis, play a role. For longer durations, a combination of common causes for diabetes and cancer, as well as the effects of diabetes and insulin exposure per se, may play a role in the association between diabetes and some cancers.

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.

Gamma-glutamyltransferase and risk of cancer in a cohort of 545,460 persons - the Swedish AMORIS study

BACKGROUND

Apart from using gamma-glutamyltransferase (GGT) as a predictor of diabetes, cardiovascular and chronic kidney disease, some evidence suggests GGT as an indicator of cancer risk. We aimed to study the association between GGT and cancer in a large Swedish cohort with 37,809 primary cancers.

METHODS

In a cohort of 545,460 persons (aged >20 years) who had a measurement of GGT in the Apolipoprotein Mortality Risk (AMORIS) study, multivariate Cox proportional hazards regression was used to investigate categories of GGT (<18, 18-36,36-72, ≥72 U/L) in relation to cancer risk. Stratified analyses were conducted by gender, levels of alanine aminotransferase (ALT) (</≥ 50 U/L), glucose (</≥ 6.11 mmol/L) and triglycerides (</≥1.71 mmol/L).

RESULTS

A positive association was found between categories of GGT and overall cancer risk (HR: 1.07 (95%CI: 1.04-1.09,), 1.18 (1.14-1.22), 1.32 (1.26-1.38) for the 2nd, 3rd and 4th categories compared to the 1st). Stratified analyses showed that for those with glucose ≥6.11 mmol/L, the association between GGT and risk of prostate, breast and liver cancer became stronger (e.g. HR for GGT ≥72 U/L and prostate cancer: 1.11 (0.98-1.26) and 1.35 (1.00-1.81) for glucose <6.11 and ≥6.11 mmol/L, respectively). With pancreatic cancer, the association with GGT was weaker for those with elevated glucose levels compared to those with normal levels. No effects of ALT or triglyceride levels on risk were found.

CONCLUSION

We found evidence of associations between elevated GGT and risk of developing different cancers. The strength of this association may vary by glucose levels because hyperglycaemia can result in oxidative stress initiating damaging pathways of carcinogenesis.

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.

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.

Does diabetes mellitus increase the risk of high-grade prostate cancer in patients undergoing radical prostatectomy?

The objective was to test the hypothesis that in patients with prostate cancer undergoing radical prostatectomy (RP), diabetic patients are at a higher risk of harboring a high-grade tumor than non-diabetic patients. We examined 2060 consecutive men who underwent RP between 2001 and 2009. Of them, 7.1% had type 2 diabetes mellitus (DM). A high-grade tumor was defined as having a Gleason score ≥ 8. Univariable and multivariable logistic regression analyses were used to test the relationship between type 2 DM and high-grade tumor. Mean patient age was 64 years (range: 45-85). Mean total PSA level was 9 ng ml(-1) (range: 1-89.5). A significantly higher percentage of diabetic patients had high-grade tumor on biopsy (16.3 vs 7.6%; P = 0.001) and on RP specimen (21.1 vs 11.7%; P = 0.001) in comparison with non-diabetic patients. In multivariable analyses, DM was an independent predictor of high-grade tumor on biopsy (odds ratio = 2.31, P = 0.001) and on final pathological specimen (odds ratio = 2.22, P = 0.002). In patients undergoing RP, those with type 2 DM had a higher risk of harboring a poorly differentiated tumor on final pathological examination.

Association between C-peptide concentration and prostate cancer incidence in the CLUE II cohort study

Diabetes, characterized by perturbations in insulin production and signaling, is inversely associated with prostate cancer risk irrespective of stage. Obesity, a diabetes risk factor, is inversely associated with localized disease but positively associated with advanced disease. To understand the complex association between hyperinsulinemia and prostate cancer, we evaluated the association of plasma C-peptide, an insulin secretion marker, with prostate cancer risk in a case-control study nested in a prospective community cohort. Prostate cancer cases (n = 264) and matched controls (n = 264) were identified in the CLUE II cohort between 1989 (baseline) and 2002. C-peptide concentration was measured in baseline plasma by ELISA. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using conditional logistic regression, adjusting for being overweight or obese and family history. Median C-peptide concentration was lower in cases (1,180 pmol/L) than in controls (1,365 pmol/L; P = 0.03). Men in the highest (versus lowest) fourth of C-peptide had a lower risk for prostate cancer (OR, 0.65; 95% CI, 0.37-1.14; P-trend = 0.08), primarily localized disease (OR, 0.44; 95% CI, 0.19-1.03; P-trend = 0.04). Associations were similar to overall, when excluding cases diagnosed during the first 5 years of follow-up, men with diabetes, or men who had not had a prostate-specific antigen test. C-peptide concentration was inversely associated with subsequent diagnosis of prostate cancer, primarily localized disease, similar to the association for obesity. However, we cannot rule out detection bias that might result if men with higher C-peptide have lower prostate-specific antigen irrespective of whether prostate cancer is present or not.

Evaluation of association of HNF1B variants with diverse cancers: collaborative analysis of data from 19 genome-wide association studies

BACKGROUND

Genome-wide association studies have found type 2 diabetes-associated variants in the HNF1B gene to exhibit reciprocal associations with prostate cancer risk. We aimed to identify whether these variants may have an effect on cancer risk in general versus a specific effect on prostate cancer only.

METHODOLOGY/PRINCIPAL FINDINGS

In a collaborative analysis, we collected data from GWAS of cancer phenotypes for the frequently reported variants of HNF1B, rs4430796 and rs7501939, which are in linkage disequilibrium (r(2) = 0.76, HapMap CEU). Overall, the analysis included 16 datasets on rs4430796 with 19,640 cancer cases and 21,929 controls; and 21 datasets on rs7501939 with 26,923 cases and 49,085 controls. Malignancies other than prostate cancer included colorectal, breast, lung and pancreatic cancers, and melanoma. Meta-analysis showed large between-dataset heterogeneity that was driven by different effects in prostate cancer and other cancers. The per-T2D-risk-allele odds ratios (95% confidence intervals) for rs4430796 were 0.79 (0.76, 0.83)] per G allele for prostate cancer (p<10(-15) for both); and 1.03 (0.99, 1.07) for all other cancers. Similarly for rs7501939 the per-T2D-risk-allele odds ratios (95% confidence intervals) were 0.80 (0.77, 0.83) per T allele for prostate cancer (p<10(-15) for both); and 1.00 (0.97, 1.04) for all other cancers. No malignancy other than prostate cancer had a nominally statistically significant association.

CONCLUSIONS/SIGNIFICANCE

The examined HNF1B variants have a highly specific effect on prostate cancer risk with no apparent association with any of the other studied cancer types.

Diabetes genes and prostate cancer in the Atherosclerosis Risk in Communities study

There is a known inverse association between type 2 diabetes (T2D) and prostate cancer (PrCa) that is poorly understood. Genetic studies of the T2D-PrCa association may provide insight into the underlying mechanisms of this association. We evaluated associations in the Atherosclerosis Risk in Communities study between PrCa and nine T2D single nucleotide polymorphisms from genome-wide association studies of T2D (in CDKAL1, CDKN2A/B, FTO, HHEX, IGF2BP2, KCNJ11, PPARG, SLC30A8, and TCF7L2) and four T2D single nucleotide polymorphisms from pre-genome-wide association studies (in ADRB2, CAPN10, SLC2A2, and UCP2). From 1987 to 2000, there were 397 incident PrCa cases among 6,642 men ages 45 to 64 years at baseline. We used race-adjusted Cox proportional hazards models to estimate associations between PrCa and increasing number of T2D risk-raising alleles. PrCa was positively associated with the CAPN10 rs3792267 G allele [hazard ratio (HR) 1.20; 95% confidence interval (CI), 1.00-1.44] and inversely associated with the SLC2A2 rs5400 Thr110 allele (HR, 0.85; 95% CI, 0.72, 1.00), the UCP2 rs660339 Val55 allele (HR, 0.84; 95% CI, 0.73, 0.97) and the IGF2BP2 rs4402960 T allele (HR, 0.79; 95% CI, 0.61-1.02; blacks only). The TCF7L2 rs7903146 T allele was inversely associated with PrCa using a dominant genetic model (HR, 0.79; 95% CI, 0.65-0.97). Further knowledge of T2D gene-PrCa mechanisms may improve understanding of PrCa etiology.

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.

Medical history, body size, and cigarette smoking in relation to fatal prostate cancer

OBJECTIVES

Prostate cancer has few known risk factors. As part of a population-based case-control study conducted in four health maintenance organizations, the authors examined the associations between fatal prostate cancer and several medical and behavioral characteristics.

METHODS

Cases were 768 health plan members who died of prostate adenocarcinoma during the period 1997-2001. We randomly selected controls (929) from the health plan membership and matched them to cases on health plan, age, race, and pattern of health plan membership. We examined medical records to obtain information on potential risk factors during the 10 years before the date on which prostate cancer was first suspected; the same reference date was used for the matched controls.

RESULTS

Anthropometric characteristics, as well as personal histories of benign prostatic hypertrophy, transurethral prostatectomy, cancer, diabetes, prostatitis, hypertension, and vasectomy were largely similar for cases and controls. Men who died from prostate cancer were more likely than controls to have been cigarette smokers according to the most recent smoking notation before the reference date (odds ratio 1.5, 95% confidence interval 1.1-2.0).

CONCLUSIONS

The observed increase in risk associated with recent cigarette smoking is consistent with the findings of several other studies. However, in contrast with some reports, we observed no connection between fatal prostate cancer and some prior health conditions or measures of body size.

Serum creatinine and prostate cancer risk in a prospective study

BACKGROUND

Several studies have examined serum creatinine as a marker for prostate cancer stage, recurrence, and prognosis. We evaluated whether serum creatinine concentration was associated with risk of developing prostate cancer in a prospective cohort of male smokers.

METHODS

A nested case-control study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study of 50- to 69-year-old Finnish men was conducted. Two controls (n = 464) were matched to each case (n = 232) on study center, intervention group, date of baseline blood draw (+/-45 days), and age (+/-5 years). Conditional logistic regression was used to calculate odds ratios and 95% confidence intervals. All P values were two-sided.

RESULTS

Cases had significantly higher prediagnostic serum creatinine concentrations compared with controls (medians of 1.13 versus 1.10 mg/dL, respectively; P = 0.004). Serum creatinine was associated with a significantly greater risk of prostate cancer (multivariate odds ratio, 2.23; 95% confidence interval, 1.33-3.75 for highest versus lowest quartile), with a significant trend (P trend = 0.0008). Exclusion of subjects with a reported history of diabetes, benign prostatic hyperplasia, or hypertension, or whose cancer was diagnosed within the first 5 years of follow-up, did not alter the association. Risk did not differ by disease stage or time from blood draw to diagnosis.

CONCLUSION

Prospectively measured serum creatinine, within normal ranges, is positively related to prostate cancer risk. Future research should reexamine the association in other populations, including any interrelationship with serum prostate-specific antigen.

Serum insulin, glucose, indices of insulin resistance, and risk of prostate cancer

BACKGROUND

The mitogenic and growth-stimulatory effects of insulin-like growth factors appear to play a role in prostate carcinogenesis, yet any direct association of circulating insulin levels and risk of prostate cancer remains unclear.

METHODS

We investigated the relationship of the level of serum insulin, glucose, and surrogate indices of insulin resistance (ie, the molar ratio of insulin to glucose and the homeostasis model assessment of insulin resistance [HOMA-IR]) to the development of prostate cancer in a case-cohort study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort of Finnish men. We studied 100 case subjects with incident prostate cancer and 400 noncase subjects without prostate cancer from the larger cohort. Fasting serum was collected 5-12 years before diagnosis. We determined insulin concentrations with a double-antibody immunochemiluminometric assay and glucose concentrations with a hexokinase assay. Multivariable logistic regression models estimated relative risks as odds ratios (ORs), and all statistical tests were two-sided.

RESULTS

Insulin concentrations in fasting serum that was collected on average 9.2 years before diagnosis among case subjects were 8% higher than among noncase subjects, and the molar ratio of insulin to glucose and HOMA-IR were 10% and 6% higher, respectively, but these differences were not statistically significant. Among subjects in the second through fourth insulin quartiles, compared with those in the first quartile, increased insulin levels were associated with statistically significantly increased risks of prostate cancer (OR = 1.50, 95% confidence interval [CI] = 0.75 to 3.03; OR = 1.75, 95% CI = 0.86 to 3.56; and OR = 2.55, 95% CI = 1.18 to 5.51; for the second through fourth insulin quartiles, respectively; P(trend) = .02). A similar pattern was observed with the HOMA-IR (OR = 2.10, 95% CI = 1.03 to 4.26; P(trend) = .02) for the highest vs lowest quartiles. Risk varied inconsistently with glucose concentration (P(trend) = .38). A stronger association between insulin level and prostate cancer risk was observed among leaner men and among men who were less physically active at work. Crude prostate cancer incidence was 154 prostate cancers per 100 000 person-years in the lowest quartile of fasting serum insulin vs 394 prostate cancers per 100 000 person-years in the highest quartile.

CONCLUSION

Elevated fasting levels of serum insulin (but not glucose) within the normal range appear to be associated with a higher risk of prostate cancer.

Significance of preoperative HbA1c level in patients with diabetes mellitus and clinically localized prostate cancer

INTRODUCTION

We investigated potential relationships of history of diabetes mellitus (DM) and glycemic control, represented by hemoglobin A1c (HbA1c) level, with characteristics of tumor among patients who received radical prostatectomy (RP) for clinically localized prostate cancer.

METHODS

We reviewed data of 740 patients who underwent RP for clinically localized prostate cancer between 2004 and 2008 without receiving preoperative radiation or hormonal treatment. Univariate and multivariate logistic regression analyses addressed the associations of history of DM and HbA1c level with known prognostic variables of prostate cancer.

RESULTS

No significant differences were observed in various preoperative and pathological parameters between those with (n = 89) and without DM (n = 651). When only the subjects with DM were divided into two groups (group 1 and 2) according to HbA1c level (<6.5% vs. >/=6.5%), group 2 demonstrated significantly higher rate of extraprostatic extension of tumor (P = 0.043) and high (>/=7) pathological Gleason score (P = 0.005) than group 1. Also among those with DM, HbA1c level was observed to be an independent predictor for high pathologic Gleason score (P = 0.010) and extraprostatic extension of tumor (P = 0.035), respectively in multivariate analyses.

CONCLUSION

Although simple history of having DM may not be a significant factor regarding aggressiveness of clinically localized prostate cancer, the glycemic control, as represented by HbA1c level, may be a useful preoperative predictor of aggressive tumor profile among patients with DM who are also diagnosed with clinically localized prostate cancer.

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.

Glucose metabolism disorders in cancer patients in a Chinese population

BACKGROUND

Characteristics of glucose metabolism disorders (GMDs) in different cancers and the contributory role of GMDs in developing cancers are still not so clear.

METHODS

Two thousand four hundred and five patients with malignancy who had been hospitalized in the First Affiliated Hospital of Jinan University were pooled as case group. Two thousand and sixteen non-cancer people who finished health examinations in the Affiliated Yangcheng Hospital of Guangzhou Medical College were enrolled as control group. We compared glucose metabolism among patients with different kinds of malignancy. Based on logistic regression models, we analyzed factors that affect the development of carcinoma.

RESULTS

(1) Among 2,408 malignancy patients, the total prevalence of diabetes mellitus (DM) and impaired fasting glucose (IFG) reached 28.0%. Pancreatic cancer, lymphoma, liver cancer, leukemia, and colorectal cancer showed most striking hyperglycemia. (2) Leukemia and esophageal cancer accounting for 12.5% and 12.1%, respectively, were the most likely to suffer from hypoglycemia. (3) Older cancer patients seem to be more vulnerable to hyperglycemia, while the younger tend to be more likely to develop hypoglycemia. (4) High level of fasting plasma glucose (FPG) was associated with lung cancer, breast cancer, leukemia, lymphoma, thyroid cancer, bladder cancer, and pancreatic cancer. Patients with DM increased risks for developing colorectal cancer, liver cancer, esophageal cancer, thyroid cancer, cervical cancer, and pancreatic cancer.

CONCLUSIONS

GMDs are frequent events in malignancy patients. Hyperglycemia and hypoglycemia are found in the same kinds or different kinds of cancers, and the incidence of hyperglycemia is higher than that of hypoglycemia. Characteristics of GMDs were dissimilar in different cancers and different ages. Hyperglycemia was a risk factor for many cancers.