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

Complex patterns and determinants of regional multiple chronic conditions across the United States

Noncommunicable chronic diseases (NCDs) are a rapidly growing global public health concern, posing substantial challenges to healthcare systems. The presence of multiple (≥2) chronic conditions (MCC) exacerbates these challenges. In this study, we constructed an integrated MCC network to comprehensively evaluate the impact of NCD prevalence and associated factors on MCC patterns. We identified four distinct MCC patterns, each with its unique set of associated risk factors. Firstly, we found that race, sedentary lifestyles, and smoking habits were significant contributors to the co-occurrence of diabetes, chronic kidney disease, and cancer. Secondly, smoking habits and mental health were identified as risk factors associated with the clusters of high cholesterol, hypertension, coronary heart disease, and arthritis. Furthermore, the comorbidity of chronic obstructive pulmonary disease and asthma was affected by socioeconomic status, smoking habits, and educational attainment, and a noteworthy reciprocal relationship existed between these two MCC combinations. Thirdly, the combination of asthma and obesity is associated with risk factors such as mental health, smoking habits, sedentary lifestyles, and binge drinking behaviors. Finally, the pattern of depression-stroke comorbidity was influenced by risk factors including mental health, age, and sleep duration. Our findings hold valuable implications for healthcare system optimization, offering a pathway to mitigate the escalating burden of NCDs. Additionally, they provide a foundation for scientific strategies aimed at the joint prevention and management of these complex conditions, ultimately enhancing public health and safety on a global scale.

Diabetes Mellitus and Prostate Cancer Risk-A Systematic Review and Meta-Analysis

INTRODUCTION

Prostate cancer is the second most commonly diagnosed malignant tumor worldwide and poses a significant challenge to public health. This systematic review and meta-analysis aims to investigate the association between diabetes mellitus and the risk of developing prostate cancer.

METHODS

We conducted a search of PubMed, Embase, and the Cochrane Library from 1998 to 2024. The risk of bias within the included studies was assessed using the Newcastle-Ottawa Scale. The DerSimonian-Laird random-effect model was employed for the meta-analysis. Heterogeneity was evaluated using a forest plot and statistically assessed via the Q test, I2 index, and p-values.

RESULTS

Forty-three studies involving a total of 3,746,769 patients were included. Both case-control (pOR = 0.68, 95% CI: 0.61-0.97; I2 = 92.24%) and cohort studies (pRR = 0.71, 95% CI: 0.59-0.99; I2 = 85.41%) suggest that diabetes mellitus is associated with a reduced risk of prostate cancer, though with significant heterogeneity (p < 0.05). Subgroup analysis revealed that the risk of developing prostate cancer was significantly higher in patients with a family history of prostate cancer (pRR = 1.25, 95% CI: 1.16-1.35; I2 = 69.51%).

CONCLUSIONS

Our meta-analysis of recent observational studies indicates that diabetes mellitus is associated with a reduced risk of developing prostate cancer.

Unraveling the biological link between diabetes mellitus and prostate cancer: Insights and implications

This article is a comprehensive study based on research on the connection between diabetes mellitus (DM) and prostate cancer (PCa). It investigates the potential role of DM as an independent risk factor for PCa, delving into the biological links, including insulin resistance and hormonal changes. The paper critically analyzes previous studies that have shown varying results and introduces mendelian randomization as a method for establishing causality. It emphasizes the importance of early DM screening and lifestyle modifications in preventing PCa, and proposes future research directions for further under-standing the DM - PCa relationship.

Poor Glycemic Control Affecting Screening of Prostate Carcinoma

Introduction Diabetes and cancer are commonly linked together. The possible links include insulin resistance, hyperinsulinemia, hyperglycemia, oxidative stress, and chronic inflammation. These are factors that have potential promoting effects on the progression of cancer in many ways. Measurement of prostate-specific antigen (PSA) is widely applied for early detection of prostate cancer. However, several factors influence serum PSA levels in men including age, benign prostatic hyperplasia, prostatitis, and body mass index (BMI). The risk of several malignancies is increased in diabetes but the risk of prostate carcinoma in diabetic patients is reduced secondary to lowering of testosterone levels during the state of hyperinsulinemia. A negative association between serum PSA levels and metformin use is also an explanation of low cancer prostate incidence with diabetes. Objective The study aims to evaluate the PSA levels in diabetic patients with poor glycemic control i.e., glycated hemoglobin (HbA1c) ≥ 7%) vs good glycemic control (HbA1c < 7%). Materials and methods Samples of PSA in diabetic patients collected in the Department of Biochemistry at Indira Gandhi Institute of Medical Sciences (IGIMS), Patna, were included. The observational study was carried out on clinically diagnosed 318 cases of diabetes attending both the outpatient and inpatient Department, IGIMS, Patna. Six ml venous blood samples were collected from patients after obtaining informed consent and ethical clearance. Patient details regarding age, complete clinical details, and general physical examinations were recorded. Serum levels of PSA, fasting plasma glucose (FPG) and HbA1c were analyzed and values were compared. The serum level of PSA was estimated by the chemiluminescent immunoassay (CLIA) method on an automated immunoassay analyzer in the Department of Biochemistry, maintaining all the quality control precautions using a control, calibrator, and reagent kit. HbA1c estimation was by chromatography technique. Fasting plasma glucose was estimated using the hexokinase method on an automated chemistry analyzer. Statistical analyses were performed using SPSS software, version 16.0 (SPSS Inc., Chicago). The median and interquartile range were calculated for numerical variables. Covariance analysis was used in the comparisons among groups. The Mann-Whitney U test was applied to detect the comparison between the two groups. Significance was determined by the P value. P value<0.05 was considered significant. Result Serum PSA value was found to be higher in (the good glycemic control group) with a median of 0.99 with an interquartile range of 3.14, than in (the bad glycemic control group) with a median of 0.49 with an interquartile range of 3.9, and the difference is statistically significant. The difference is also statistically significant in the subgroup (i) with PSA value <4 ng/ml. In subgroups (ii) and (iii), PSA values 4 ng/ml-8 ng/ml and PSA values >8 ng/ml respectively, no significant differences were found. Conclusion It was found that serum prostate-specific antigen levels have been lower in diabetic patients with poor glycemic control than in good glycemic control. Future studies with a larger sample size and detailed information on diabetes duration and management are recommended.

Significantly reduced incidence and improved survival from prostate cancer over 25 years

BACKGROUND

Prostate cancer (PCa) was the second most frequent cancer and the fifth leading cause of cancer death among men in 2020. The aim of this study was to analyze trends in the incidence, mortality and survival of PCa in Girona, Spain, over 25 years.

METHODS

Population-based study of PCa collected in the Girona Cancer Registry, 1994-2018. Age-adjusted incidence and mortality rates were calculated per 100,000 men-year. Joinpoint regression models were used for trends, calculating the annual percentage changes (APC). Observed and net survival were analyzed using Kaplan-Meier and Pohar-Perme estimations, respectively.

RESULTS

A total of 9,846 cases of PCa were registered between 1994-2018. The age-adjusted incidence and mortality rates were 154.7 (95%CI: 151.7 157.8) and 38.9 (95%CI: 37.3 -40.6), respectively. An increased incidence of 6.2% was observed from 1994 to 2003 (95%CI: 4.4 -8.1), and a decrease of -2.7% (95%CI: -3.5 -;-1.9) between 2003 and 2018. Mortality APC was -2.6% (95%CI: -3.3 --2.0). Five-year observed and net survival were 72.8% (95%CI: 71.8 - 73.7) and 87.2% (95%CI: 85.9 - 88.4), respectively. Five-year net survival increased over time from 72.9% (1994-1998) to 91.3% (2014-2018).

CONCLUSIONS

The analyses show a clear reduction in PCa incidence rates from 2003 on, along with an increase in overall survival when comparing the earlier period with more recent years.

Testosterone Deficiency is Not Protective Against the Development of Adenocarcinoma of the Prostate in a Type 1 Diabetic Patient

We present a case of prostate cancer (PC) developing in a hypogonadal patient with well-controlled type 1 diabetes. The purpose of reporting this case is to emphasize that regular prostate examinations and prostate-specific antigen (PSA) measurements should be preformed in the diabetic male, even though the incidence of PC is lower in this group of patients. In addition, these examinations and tests need to be preformed even in the hypogonadal patient with diabetes since the presence of a low serum testosterone (T) level does not preclude the development of PC. This is because the development of PC is not related to serum androgen levels but to the androgen levels within the prostate, and dihydrotestosterone (DHT) levels and not T levels within the prostate gland are responsible for the development of PC. In the hypogonadal male, intraprostatic DHT may be high since DHT can be formed from adrenal androgens, particularly androstenedione, through activation of 5α-reductase 2, which is the minority enzyme in the normal prostate but becomes the major enzyme in the formation and growth of PC.

Hormonal patterns in men with prediabetes and diabetes in NHANES III: possible links with prostate cancer

PURPOSE

Pathways involving sex hormones and insulin-like growth factors (IGFs) have been proposed to explain, in part, the lower risk of prostate cancer among men with diabetes. To gain insights into potential biological mechanisms we explored differences in serum concentrations of sex hormones and IGFs across the trajectory from normoglycemia to prediabetes to poorly controlled diabetes.

METHODS

Using cross-sectional data from the National Health and Nutrition Examination Survey III we examined differences in levels of circulating sex hormones, sex hormone-binding globulin (SHBG), IGF-1, and IFG-binding protein 3 (IGFBP-3), according to diabetes status: no diabetes [n = 648], prediabetes [n = 578], undiagnosed diabetes [n = 106], well-controlled diabetes [n = 42], and poorly controlled diabetes [n = 56]. Adjusted geometric mean concentrations were derived using multivariable linear regression, adjusted for age, race, and other lifestyle factors.

RESULTS

Total testosterone concentrations were lower among prediabetics (4.89 ng/mL, 95% confidence interval (CI) 4.95-5.21) than men without prediabetes/diabetes (5.29 ng/mL, 95% CI 5.06-5.53) but did not reduce further across diabetes groups. Concentrations of estradiol, estimated free testosterone, SHGB, IGF-1, and IGFBP-3 did not differ. While the ratio of IGF-1 to IGFBP-3 was lower among men with prediabetics and undiagnosed diabetes than men without prediabetes/diabetes, there was no trend across groups. A positive trend for the ratio of estradiol-to-testosterone levels was observed across groups (p trend = 0.045).

CONCLUSION

Our findings do not provide clear support for either an androgen driven or IGF-driven pathway for the inverse association between diabetes and prostate cancer risk.

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.

Outcomes of prostate cancer screening among men using antidiabetic medication

Diabetic men have decreased risk for prostate cancer (PCa) overall and lower PSA compared to non-diabetics. This may affect the outcomes of PSA-based screening. We investigated the effect of PSA-based screening at 4-year intervals on PCa incidence and mortality separately among users and non-users of antidiabetic medication with the hypothesis that screening would detect less low-grade cancer and more high-grade cancer in diabetic men. A cohort of 80,458 men from the Finnish Randomized Study of Screening for Prostate Cancer (FinRSPC) were linked to national prescription database to obtain information on antidiabetic medication purchases. PCa risk and mortality were compared between the FinRSPC screening arm (SA) and the control arm (CA) separately among users and non-users of antidiabetic medication. Among antidiabetic medication users median PSA was lower than in non-users (0.93 and 1.09 ng/ml, respectively, P for difference = 0.001). Screening increased overall PCa incidence compared to CA after the first screen both among medication users and non-users (HR 1.31, 95% CI 1.08–1.60 and HR 1.55, 95% CI 1.44–1.66, respectively). On the second and third screen the difference between SA and CA attenuated only among medication users. Detection of Gleason 6 tumors was lower among medication users, whereas no difference was observed in detection of Gleason 8–10 cancers. Concordantly, screening affected PCa mortality similarly regardless of antidiabetic medication use (HR 0.38, 95% CI 0.14–1.07 and HR 0.19, 95% CI 0.11–0.33 among users and non-users after three screens, respectively. P for difference = 0.18). Median PSA is lower in men using antidiabetic drugs than among non-users. Systematic PSA screening detects less low-risk tumors among medication users, whereas detection of high-risk tumors and mortality effects are similar regardless of medication use. This suggests that antidiabetic medication users may form a suitable target group for PCa screening, with less screening-related overdiagnosis of indolent tumors.

Diabetes and Prostate Cancer Outcomes in Obese and Nonobese Men After Radical Prostatectomy

Background

The link between diabetes and prostate cancer progression is poorly understood and complicated by obesity. We investigated associations between diabetes and prostate cancer-specific mortality (PCSM), castrate-resistant prostate cancer (CRPC), and metastases in obese and nonobese men undergoing radical prostatectomy (RP).

Methods

We included 4688 men from the Shared Equal Access Regional Cancer Hospital cohort of men undergoing RP from 1988 to 2017. Diabetes prior to RP, anthropometric, and clinical data were abstracted from 6 Veterans Affairs Medical Centers electronic medical records. Primary and secondary outcomes were PCSM and metastases and CRPC, respectively. Multivariable-adjusted hazard ratios (adj-HRs) and 95% confidence intervals (CIs) were estimated for diabetes and PCSM, CRPC, and metastases. Adjusted hazard ratios were also estimated in analyses stratified by obesity (body mass index: nonobese <30 kg/m²; obese ≥30 kg/m²). All statistical tests were 2-sided.

Results

Diabetes was not associated with PCSM (adj-HR = 1.38, 95% CI = 0.86 to 2.24), CRPC (adj-HR = 1.05, 95% CI = 0.67 to 1.64), or metastases (adj-HR = 1.01, 95% CI = 0.70 to 1.46), among all men. Interaction terms for diabetes and obesity were statistically significant in multivariable models for PCSM, CRPC, and metastases (P ≤ .04). In stratified analyses, in obese men, diabetes was associated with PCSM (adj-HR = 3.06, 95% CI = 1.40 to 6.69), CRPC (adj-HR = 2.14, 95% CI = 1.11 to 4.15), and metastases (adj-HR = 1.57, 95% CI = 0.88 to 2.78), though not statistically significant for metastases. In nonobese men, inverse associations were suggested for diabetes and prostate cancer outcomes without reaching statistical significance.

Conclusions

Diabetes was associated with increased risks of prostate cancer progression and mortality among obese men but not among nonobese men, highlighting the importance of aggressively curtailing the increasing prevalence of obesity in prostate cancer survivors.

Antidiabetic Drugs and Prostate Cancer Prognosis in a Finnish Population-Based Cohort

BACKGROUND

Hyperinsulemia and glycemic control may play a role as prostate cancer prognostic factors, whereas use of certain antidiabetic drugs, that is metformin, could improve the prognosis. We examined the link between antidiabetic medication use and prostate cancer survival taking into account simultaneous use of multiple drugs.

METHODS

The study cohort composed of 6,537 men in The Finnish Randomized Study of Screening for Prostate Cancer with prostate cancer diagnosed 1996 to 2009. Use of medication was attained from the nationwide prescription database of the Social Insurance Institution of Finland. Median follow-up was 9.2 years postdiagnosis. A total of 1,603 (24,5%) men had used antidiabetic medication. A total of 771 men died of prostate cancer during the follow-up. We used multivariable-adjusted Cox regression to evaluate the risk of prostate cancer death and onset of androgen deprivation therapy (ADT) with adjustment for prostate cancer clinical characteristics, comorbidities and use of other drugs. Separate analyses were further adjusted for blood glucose.

RESULTS

Risk of prostate cancer death was higher among antidiabetic drug users overall (HR = 1.42; 95% CI, 1.18-1.70) compared with nonusers, separately among insulin and metformin users. Adjustment for blood glucose level abolished the risk increase. Risk of ADT initiation was increased among the medication users (HR = 1.26; 95% CI, 1.05-1.49).

CONCLUSIONS

Men with prostate cancer using antidiabetic medication are generally at increased risk of dying from prostate cancer compared with nonusers. The risk association is driven by underlying diabetes, as adjustment for blood glucose level ameliorates the risk increase.

IMPACT

Type 2 diabetes should be considered as a risk factor when considering prostate cancer prognosis.

Risk of cancer incidence and mortality associated with diabetes: A systematic review with trend analysis of 203 cohorts

AIM

Whether the relative risk of cancer incidence and mortality associated with diabetes has changed over time is unknown.

DATA SYNTHESIS

On August 12th, 2020, we electronically searched for observational studies reporting on the association between diabetes and cancer. We estimated temporal trends in the relative risk of cancer incidence or mortality associated with diabetes and calculated the ratio of relative risk (RRR) comparing different periods. As many as 193 eligible articles, reporting data on 203 cohorts (56,852,381 participants; 3,735,564 incident cancer cases; 185,404 cancer deaths) and covering the period 1951-2013, were included. The relative risk of all-site cancer incidence increased between 1980 and 2000 [RRR 1990 vs.1980: (1.24; 95% CI: 1.16, 1.34); 2000 vs.1990: (1.23; 1.15, 1.31)] and stabilised thereafter at a relative risk of 1.2; the relative risk of all-site cancer mortality was constant at about 1.2 from 1980 to 2010. Both magnitudes and trends in relative risk varied across cancer sites: the relative risk of colorectal, female breast, and endometrial cancer incidence and pancreatic cancer mortality was constant during the observed years; it increased for bladder, stomach, kidney, and pancreatic cancer incidence until 2000; and decreased for liver while increased for prostate, colon and gallbladder cancer incidence after 2000.

CONCLUSIONS

Alongside the increasing prevalence of diabetes, the temporal patterns of the relative risk of cancer associated with diabetes may have contributed to the current burden of cancer in people with diabetes.

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.

Examining the relationship between diabetes and prostate cancer through changes in screening guidelines

PURPOSE

Previous studies have found that men with diabetes are at reduced risk of prostate cancer compared to men without diabetes. The lower risk could be due to biologic differences and/or a diagnosis bias from use of the prostate-specific antigen (PSA) test as a screening and diagnostic tool. We sought to further examine the relationship between diabetes and incidence of prostate cancer and examine the potential impact of changes in PSA screening guidelines in 2008 and 2012.

METHODS

We used 2004-2015 Surveillance, Epidemiology and End Results (SEER)-Medicare data and limited the study population to men aged 67-74 with at least 2 years of continuous enrollment. Using the 5% Medicare sample as the denominator and prostate cancer cases as the numerator, we calculated age-adjusted rate ratios (RR) in 2006-2011 and 2012-2015 by diabetes status, overall and by tumor grade. We used multivariable logistic regression to compare tumor characteristics by diabetes status.

RESULTS

Men with diabetes had lower incidence rates of prostate cancer compared to men without diabetes in 2006-2011 [RR = 0.89 95% confidence interval (CI) 0.87-0.91] and 2012-2015 (RR = 0.92 95% CI 0.89-0.95) but the slight attenuation toward the null in 2012-2015 was primarily due to the change in RRs for low-grade tumors.

CONCLUSION

We found differences in the risk and characteristics of prostate cancer by diabetes status and that some risks have changed over time as guidelines have changed. With lower PSA use in the more recent time-period, rates of low-grade tumors have become more similar by diabetes status.

Association of Type 2 Diabetes With Cancer: A Meta-analysis With Bias Analysis for Unmeasured Confounding in 151 Cohorts Comprising 32 Million People

BACKGROUND AND PURPOSE

Whether the association between type 2 diabetes (T2D) and cancer is causal remains controversial. The goal of this work is to assess the robustness of the observational associations between T2D and cancer to unmeasured confounding.

DATA SOURCES AND STUDY SELECTION

PubMed, Web of Science, and the Cochrane library were systematically searched on 10 January 2019 for observational studies investigating associations between T2D and cancer incidence or mortality.

DATA EXTRACTION AND DATA SYNTHESIS

Cohort-level relative risk (RR) was extracted. RRs were combined in random-effects meta-analyses and pooled estimates used in bias analyses. A total of 151 cohorts (over 32 million people, 1.1 million cancer cases, and 150,000 cancer deaths) were included. In meta-analyses, T2D was associated with incidence of several cancers, from prostate (RR 0.83; 95% CI 0.79, 0.88) to liver (2.23; 1.99, 2.49), and with mortality from pancreatic cancer (1.67; 1.30, 2.14). In bias analyses, assuming an unmeasured confounding associated with both T2D and cancer with a RR of 1.5, the proportion of studies with a true effect size larger than a RR of 1.1 (i.e., 10% increased risk in individuals with T2D) was nearly 100% for liver, pancreatic, and endometrial, 86% for gallbladder, 67% for kidney, 64% for colon, 62% for colorectal, and <50% for other cancer incidences, and 92% for pancreatic cancer mortality.

LIMITATIONS

Biases other than unmeasured confounding were not analytically assessed.

CONCLUSIONS

Our findings strongly suggest a causal association between T2D and liver, pancreatic, and endometrial cancer incidence, and pancreatic cancer mortality. Conversely, associations with other cancers were less robust to unmeasured confounding.

Untangling the association between prostate-specific antigen and diabetes: a systematic review and meta-analysis

Objectives

Several studies have shown an inverse association between diabetes mellitus and prostate cancer (PCa). Some researchers suggest that this relationship is due to reduced PCa detection in diabetics due to lower prostate-specific antigen (PSA) levels compared to non-diabetics. Our objective is to analyze the impact of diabetes on PSA in asymptomatic men without known prostate pathology and without prior prostate intervention.

Methods

We searched Medline (via PubMed), Embase and Scopus. We included studies that reported the relationship between serum PSA levels and diabetes or diabetes treatment in asymptomatic adult men without known prostate pathology, and without prior prostate intervention. Pooled mean differences were compared between diabetics and non-diabetics.

Results

Of 2,392 screened abstracts, thirteen studies met the inclusion criteria and 8 (62%) reported appropriate measures that could be included in a meta-analysis. Eleven (85%) examined the influence of diabetes on PSA levels and 8 (62%) evaluated the influence of diabetes treatments on PSA levels. Overall diabetics had a significantly lower PSA level compared to non-diabetics (mean difference: -0.07 ng/mL; 95% CI -0.10, -0.04).

Conclusions

Diabetes and related factors (such as disease duration, severity and treatment) were significantly associated with lower PSA levels among asymptomatic men, yet differences were small and are unlikely to influence PCa detection in a screening setting.

Association of type 2 diabetes mellitus and antidiabetic medication with risk of prostate cancer: a population-based case-control study

BACKGROUND

Prostate cancer (PCa) and type 2 diabetes mellitus (T2DM) are prevalent conditions that often occur concomitantly. However, many aspects of the impact of T2DM, particularly the duration of T2DM and antidiabetic medications, on PCa risk are poorly understood.

METHODS

To assess the association of duration of T2DM and antidiabetic medication with PCa risk, we designed a matched case-control study, including 31,415 men with PCa and 154,812 PCa-free men in Prostate Cancer data Base Sweden (PCBaSe) 4.1.

RESULTS

Overall, a decreased risk of PCa was observed for men with T2DM (odds ratio (OR): 0.81, 95% confidence interval (CI): 0.78-0.84), as compared to men without T2DM. The decreased risk of PCa was consistently showed across duration of T2DM. With respect to use of antidiabetic drugs, this inverse association with duration was also found for all medications types, as compared to men without T2DM, including insulin, metformin and sulphonylurea (SU) (e.g. 3- < 5 yr insulin OR:0.69, 95%CI:0.60-0.80; 3- < 5 yr metformin OR: 0.82, 95%CI: 0.74-0.91; 3- < 5 yr SU OR: 0.72, 95%CI: 0.62-0.83). When stratifying by PCa risk categories, this decreased risk was most evident for diagnosis of low and intermediate-risk PCa (low-risk OR: 0.65, 95%CI: 0.66-0.70, intermediate-risk OR: 0.80, 95%CI: 0.75-0.85).

CONCLUSIONS

The study showed an inverse association between pre-existing T2DM and PCa across different durations of T2DM and all types of T2DM medication received. This inverse association was most evident for low- and intermediate-risk PCa, suggesting that whilst T2DM and its medication may protect some men from developing PCa, the relationship warrants further study.

Site-specific cancer risk in patients with type 2 diabetes: a nationwide population-based cohort study in Korea

BACKGROUND/AIMS

We aimed to evaluate site-specific cancer risk in diabetic patients and to investigate causal and temporal relationships by analyzing organ-specific cancer risk according to the duration of diabetes.

METHODS

Using a database provided by the Korean National Health Insurance Service, we conducted a retrospective, population-based cohort study of adults aged ≥ 30 years from January 2005 to December 2013. To verify the possibility of detection bias or reverse causation, we compared hazard ratios (HRs) for each cancer according to the following duration of diabetes: less than 6 months, 6 months to 3 years, and more than 3 years.

RESULTS

The incidence of overall cancer per 1,000 person-years was higher in patients with diabetes than in those without diabetes (20.36 vs. 10.83). The overall cancer risk according to the duration of diabetes was the highest within the first 6 months after diagnosis (HR, 2.03; 95% confidence interval [CI], 1.99 to 2.07), and the HR decreased with the duration of diabetes, ranging from 1.19 (95% CI, 1.18 to 1.21) between 6 months and 3 years to 1.12 (95% CI, 1.11 to 1.13) after 3 years. Both overall cancer risk and HR remained significantly higher in patients with diabetes than in those without diabetes. The risk for prostate cancer was higher in men with diabetes than in those without diabetes (HR, 1.12; 95% CI, 1.10 to 1.14). In women, the risk for endometrial cancer was significantly higher in patients with diabetes than in those without diabetes throughout the duration of diabetes.

CONCLUSION

The risk for stomach, colorectum, liver, pancreas, and kidney cancer appeared to be higher in patients with diabetes than in those without diabetes regardless of the sex or duration of diabetes.

Association Between Antidiabetic Medications and Prostate-Specific Antigen Levels and Biopsy Results

IMPORTANCE

Diabetic men appear to have a lower risk of prostate cancer. Whether antidiabetic medications are protective or potentially mask prostate cancer by lowering prostate-specific antigen (PSA) levels is unclear.

OBJECTIVE

To examine the associations of antidiabetic medication use with (1) PSA levels, (2) frequency of PSA testing, (3) receipt of biopsy following elevated PSA results, and (4) prostate cancer detection at biopsy.

DESIGN, SETTING, AND PARTICIPANTS

Population-based cohort study using data from the Stockholm PSA and Biopsy Register. Participants were all prostate cancer-free men aged 40 to 79 years residing in Stockholm County, Sweden, between January 1, 2006, and December 31, 2015. Data were analyzed from November 2018 to March 2019.

EXPOSURES

One or more prescription for metformin, sulfonylurea, or insulin, as recorded in Sweden's National Prescribed Drug Register.

MAIN OUTCOMES AND MEASURES

Levels of PSA following first exposure to antidiabetic medications were assessed using multivariable linear regression. Frequency of PSA testing was assessed via multivariable Poisson regression. Biopsy following elevated PSA (≥3.0 ng/mL) and prostate cancer detection at biopsy were assessed via multivariable logistic regression.

RESULTS

The cohort of 564 666 men (median [range] age, 65 [40-79] years) consisted of 4583 men initially exposed to metformin, 1104 exposed to sulfonylurea, and 978 exposed to insulin who were age matched with unexposed men (1:5). Exposed men had lower median (interquartile range) PSA levels before starting antidiabetic medications compared with unexposed men (1.2 [0.7-2.5] vs 1.6 [0.8-3.2] ng/mL). After accounting for baseline differences, PSA levels did not vary from those of unexposed men following exposure to antidiabetic medications. Frequency of PSA testing was higher for those receiving metformin (rate ratio, 1.07; 95% CI, 1.06-1.09) and sulfonylurea (rate ratio, 1.06; 95% CI, 1.03-1.08) but was lower for those receiving insulin (rate ratio, 0.79; 95% CI, 0.77- 0.81). Likelihood of biopsy after elevated PSA was lower among men receiving metformin (odds ratio, 0.87; 95% CI, 0.80-0.96) and insulin (odds ratio, 0.83; 95% CI, 0.74-0.93). There were no differences in prostate cancer detection at biopsy, regardless of PSA levels that triggered the biopsy.

CONCLUSIONS AND RELEVANCE

This study's findings do not support the hypothesis that the inverse association between diabetes and prostate cancer is mediated through antidiabetic medications lowering PSA levels to mask prostate cancer. They do suggest potential detection bias due to fewer biopsies among men receiving antidiabetic medications, which may explain the lower prostate cancer risk in men with diabetes.

Factors associated with false negative and false positive results of prostate-specific antigen (PSA) and the impact on patient health: Cohort study protocol

INTRODUCTION

Prostate-specific antigen (PSA) is the main tool for early detection, risk stratification and monitoring of prostate cancer (PCa). However, there are controversies about the use of PSA as a population screening test because of the high potential for overdiagnosis and overtreatment associated. The net benefit of screening is unclear and according to the available recommendations, it should be offered to well-informed men with an adequate health status and a life-expectancy of at least 10 years or to men at elevated risk of having PCa. In addition, the factors that influence test results are unclear, as is impact of false positive or negative results on patient health.Our objective is to assess the clinical and analytical factors associated with the presence of false positive and false negative results and the diagnostic/therapeutic process followed by these patients.

METHODS AND ANALYSIS

A prospective observational cohort study will be carried out. We will include a cohort of patients with a positive PSA result (1.081 patients) and a sample of patients with negative results (572 patients); both will be followed for 2 years by reviewing medical records to assess the variables associated with these results, as well as characteristics of patient management after a positive PSA value. We will include those patients with a PSA determination from 2 hospitals in the Valencian Community. Patients who have been previously diagnosed with prostate cancer or who are being followed for previous high PSA values will be excluded.

DISCUSSION

The study will estimate the frequency of false positive and false negative PSA results in routine clinical practice, and allow us to quantify the potential harm caused.

STUDY REGISTRATION

Clinicaltrials.gov (https://clinicaltrials.gov/): NCT03978299, June 7, 2019.

Variable selection in semiparametric nonmixture cure model with interval-censored failure time data: An application to the prostate cancer screening study

Censored failure time data with a cured subgroup is frequently encountered in many scientific areas including the cancer screening research, tumorigenicity studies, and sociological surveys. Meanwhile, one may also encounter an extraordinary large number of risk factors in practice, such as patient's demographic characteristics, clinical measurements, and medical history, which makes variable selection an emerging need in the data analysis. Motivated by a medical study on prostate cancer screening, we develop a variable selection method in the semiparametric nonmixture or promotion time cure model when interval-censored data with a cured subgroup are present. Specifically, we propose a penalized likelihood approach with the use of the least absolute shrinkage and selection operator, adaptive least absolute shrinkage and selection operator, or smoothly clipped absolute deviation penalties, which can be easily accomplished via a novel penalized expectation-maximization algorithm. We assess the finite-sample performance of the proposed methodology through extensive simulations and analyze the prostate cancer screening data for illustration.

Chronic inflammatory diseases, anti-inflammatory medications and risk of prostate cancer: a population-based case-control study

Background

Whether chronic inflammation increases prostate cancer risk remains unclear. This study investigated whether chronic inflammatory diseases (CID) or anti-inflammatory medication use (AIM) were associated with prostate cancer risk.

Methods

Fifty-five thousand nine hundred thirty-seven cases (all prostate cancer, 2007–2012) and 279,618 age-matched controls were selected from the Prostate Cancer Database Sweden. CIDs and AIMs was determined from national patient and drug registers. Associations were investigated using conditional logistic regression, including for disease/drug subtypes and exposure length/dose.

Results

Men with a history of any CID had slightly increased risk of any prostate cancer diagnosis (OR: 1.08; 95%CI: 1.04–1.12) but not ‘unfavourable’ (high-risk or advanced) prostate cancer. Generally, risk of prostate cancer was highest for shorter exposure times. However, a positive association was observed for asthma > 5 years before prostate cancer diagnosis (OR: 1.21; 95%CI: 1.05–1.40). Risk of prostate cancer was increased with prior use of any AIMs (OR: 1.26; 95%CI: 1.24–1.29). A positive trend with increasing cumulative dose was only observed for inhaled glucocorticoids (p < 0.011).

Conclusion

Detection bias most likely explains the elevated risk of prostate cancer with prior history of CIDs or use of AIMs, given the higher risk immediately after first CID event and lack of dose response. However, findings for length of time with asthma and dose of inhaled glucocorticoids suggest that asthma may increase risk of prostate cancer through other pathways.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5846-3) contains supplementary material, which is available to authorized users.

Hyperglycemia, Classified with Multiple Biomarkers Simultaneously in Men without Diabetes, and Risk of Fatal Prostate Cancer

The association between hyperglycemia and prostate cancer risk is inconsistent, and its association with prostate cancer mortality is understudied. Thus, we investigated the association between hyperglycemia and prostate cancer risk and mortality using multiple biomarkers simultaneously to classify hyper- and normoglycemia. We conducted a prospective analysis of 5,162 cancer-free men attending visit 2 (1990-1992) of the Atherosclerosis Risk in Communities (ARIC) study followed for total (N = 671) and lethal (N = 69) prostate cancer incidence and prostate cancer mortality (N = 64) through 2012. Men without diagnosed diabetes were classified as normo- or hyperglycemic using joint categories of fasting glucose, glycated hemoglobin, and glycated albumin (or fructosamine) defined by clinical or research cutpoints. We evaluated the multivariable-adjusted association of hyperglycemia with prostate cancer incidence and mortality using Cox proportional hazards regression; men with diagnosed diabetes were included as a separate exposure category. Among 4,753 men without diagnosed diabetes, 61.5% were classified as having hyperglycemia (high on ≥1 biomarker). HbA1c and glycated albumin together classified 61.9% of 1,736 men with normal fasting glucose as normoglycemic. Compared with men who were normal on all three biomarkers, men who were high on ≥1 biomarker had an increased risk of lethal [HR, 2.50; 95% confidence interval (CI), 1.12-5.58] and fatal (HR, 3.20; 95% CI, 1.26-8.48) disease, but not total prostate cancer incidence (HR, 0.98; 95% CI, 0.81-1.20); associations were similar including fructosamine instead of glycated albumin. Our findings indicate hyperglycemia is associated with an increased risk of lethal and fatal prostate cancer, but not total prostate cancer incidence.

The relationship between diabetes, prostate-specific antigen screening tests, and prostate cancer

PURPOSE

Men with diabetes have been found to have a reduced risk of prostate cancer (PCa), potentially due to detection bias from lower prostate-specific antigen (PSA) levels or inhibition of tumor growth. Understanding if lower PCa rates are due to a lower risk of the disease or a detection bias from PSA testing can help inform the benefits and harms from prostate cancer screening.

METHODS

We used data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Screening Trial to assess the impact of PSA screening on PCa in men with diabetes and the potential role of detection bias and/or slower tumor growth. Comparing men by diabetes status, we calculated age-adjusted incidence rates by tumor grade and compared screening results, PSA levels, and tumor characteristics.

RESULTS

Men with diabetes had lower rates of PCa but was limited to low- and intermediate-grade tumors. Men with diabetes were less likely to be biopsied after their first positive screening test and men diagnosed with low/intermediate-grade tumors had significantly more advanced tumors with higher PSA levels.

CONCLUSIONS

Our findings provide additional evidence that detection bias is likely contributing to the lower rates of low- and intermediate-grade prostate cancers.

Epidemiology of prostate cancer in Asian countries

The incidence of prostate cancer has been increasing worldwide in recent years. The GLOBOCAN project showed that prostate cancer was the second most frequently diagnosed cancer and the fifth leading cause of cancer mortality among men worldwide in 2012. This trend has been growing even in Asian countries, where the incidence had previously been low. However, the accuracy of data about incidence and mortality as a result of prostate cancer in some Asian countries is limited. The cause of this increasing trend is multifactorial. One possible explanation is changes in lifestyles due to more Westernized diets. The incidence is also statistically biased by the wide implementation of early detection systems and the accuracy of national cancer registration systems, which are still immature in most Asian countries. Mortality rate decreases in Australia, New Zealand and Japan since the 1990s are possibly due to the improvements in treatment and/or early detection efforts employed. However, this rate is increasing in the majority of other Asian countries. Studies of latent and incidental prostate cancer provide less biased information. The prevalence of latent and incidental prostate cancer in contemporary Japan and Korea is similar to those in Western countries, suggesting the influence of lifestyle changes on carcinogenesis. Many studies reported evidence of both congenital and acquired risk factors for carcinogenesis of prostate cancer. Recent changes in the acquired risk factors might be associated with the increasing occurrence of prostate cancer in Asian countries. This trend could continue, especially in developing Asian countries.

Fasting blood glucose, glycaemic control and prostate cancer risk in the Finnish Randomized Study of Screening for Prostate Cancer

Background

Diabetic men have lowered overall risk of prostate cancer (PCa), but the role of hyperglycaemia is unclear. In this cohort study, we estimated PCa risk among men with diabetic fasting blood glucose level.

Methods

Participants of the Finnish Randomized Study of Screening for Prostate Cancer (FinRSPC) were linked to laboratory database for information on glucose measurements since 1978. The data were available for 17,860 men. Based on the average yearly level, the men were categorised as normoglycaemic, prediabetic, or diabetic. Median follow-up was 14.7 years. Multivariable-adjusted Cox regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs) for prostate cancer overall and separately by Gleason grade and metastatic stage.

Results

In total 1,663 PCa cases were diagnosed. Compared to normoglycaemic men, those men with diabetic blood glucose level had increased risk of PCa (HR 1.52; 95% CI 1.31–1.75). The risk increase was observed for all tumour grades, and persisted for a decade afterwards. Antidiabetic drug use removed the risk association. Limitations include absence of information on lifestyle factors and limited information on BMI.

Conclusions

Untreated diabetic fasting blood glucose level may be a prostate cancer risk factor.

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.

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.

Association of Family History of Type 2 Diabetes with Prostate Cancer: A National Cohort Study

Background

Personal history of type 2 diabetes mellitus (T2DM) is associated with a lower incidence of prostate cancer, but the underlying mechanisms are largely unknown. We hypothesized that genetic factors that are involved in the development of T2DM might protect against prostate cancer.

Methods

We used a few Swedish registers, including the Swedish Multigeneration Register and the Cancer Register, to examine the risk of prostate cancer among men with a family history of T2DM. Standardized incidence ratios were used to calculate the relative risk.

Results

The overall risk of prostate cancer among men with a familial history of T2DM was 0.87 (95% CI: 0.86–0.89) as compared to matched controls. The risk was even lower for those multiple affected relatives with T2DM, and it was 0.86 for those with two affected relatives and 0.67 for those with three and more affected relatives.

Conclusion

Family history of T2DM was associated with a lower incidence of prostate cancer, and the risk was even lower for those with more than one affected relative. Our study strongly suggests that genetic factors or shared familial factors, such as obesity, that contributed to T2DM may protect against prostate cancer.

Epidemiology of Prostate Cancer

Prostate cancer is the most common malignancy among males worldwide, and is the second leading cause of cancer death among men in United States. According to GLOBOCAN (2012), an estimated 1.1 million new cases and 307,000 deaths were reported in 2012. The reasons for the increase of this disease are not known, but increasing life expectancy and modified diagnostic techniques have been suggested as causes. The established risk factors for this disease are advancing age, race, positive family history of prostate cancer and western diet (use of fat items). Several other risk factors, such as obesity, physical activity, sexual activity, smoking and occupation have been also associated with prostate cancer risk, but their roles in prostate cancer etiology remain uncertain. This mini-review aims to provide risk factors, disease knowledge, prevalence and awareness about prostate cancer.

Cancer incidence in persons with type 1 diabetes: a five-country study of 9,000 cancers in type 1 diabetic individuals

AIMS/HYPOTHESIS

An excess cancer incidence of 20-25% has been identified among persons with diabetes, most of whom have type 2 diabetes. We aimed to describe the association between type 1 diabetes and cancer incidence.

METHODS

Persons with type 1 diabetes were identified from five nationwide diabetes registers: Australia (2000-2008), Denmark (1995-2014), Finland (1972-2012), Scotland (1995-2012) and Sweden (1987-2012). Linkage to national cancer registries provided the numbers of incident cancers in people with type 1 diabetes and in the general population. We used Poisson models with adjustment for age and date of follow up to estimate hazard ratios for total and site-specific cancers.

RESULTS

A total of 9,149 cancers occurred among persons with type 1 diabetes in 3.9 million person-years. The median age at cancer diagnosis was 51.1 years (interquartile range 43.5-59.5). The hazard ratios (HRs) (95% CIs) associated with type 1 diabetes for all cancers combined were 1.01 (0.98, 1.04) among men and 1.07 (1.04, 1.10) among women. HRs were increased for cancer of the stomach (men, HR 1.23 [1.04, 1.46]; women, HR 1.78 [1.49, 2.13]), liver (men, HR 2.00 [1.67, 2.40]; women, HR 1.55 [1.14, 2.10]), pancreas (men, HR 1.53 [1.30, 1.79]; women, HR 1.25 [1.02,1.53]), endometrium (HR 1.42 [1.27, 1.58]) and kidney (men, HR 1.30 [1.12, 1.49]; women, HR 1.47 [1.23, 1.77]). Reduced HRs were found for cancer of the prostate (HR 0.56 [0.51, 0.61]) and breast (HR 0.90 [0.85, 0.94]). HRs declined with increasing diabetes duration.

CONCLUSION

Type 1 diabetes was associated with differences in the risk of several common cancers; the strength of these associations varied with the duration of diabetes.

The effects of serum from prostate cancer patients with elevated body mass index on prostate cancer cells in vitro

We examined whether serum from obese, compared to non-obese, PCa (prostate cancer) patients creates a growth-enhancing tumor micro-environment in vitro. Serum from 80 subjects was divided into four groups: normal weight men with and without PCa and overweight/obese men with and without PCa. Cell proliferation, migration, and invasion were measured in LNCaP, and PC3 cells treated with patient serum were obtained from the above groups. The results reveal that proliferation of LNCaP cells was significantly (P = 0.05) greater with serum from non-obese (mean = 1.26 ± 0.20) compared to that from obese patients (mean = 1.16 ± 0.19). Serum from obese PCa patients compared to non-obese PCa patients induced significantly greater amounts of cell migration (P < 0.01) in PC3 cells. Serum from obese patients induced significantly (P < 0.01) lower amounts of cell invasion (mean = 8.2 ± 4.5) compared to non-obese patients (mean = 18.1 ± 5.0) when treated on PC3 cells. Serum TNF-α (tumor necrosis factor alpha) levels correlated with LNCaP cell proliferation in vitro in non-obese PCa (P < 0.01) and non-obese control groups (P = 0.05). All statistical calculations controlled for age, since the PCa patient groups were significantly older than the control groups (P < 0.01). In conclusion, serum from obese PCa patients induced greater PCa cell migration and lower cell proliferation and invasion in vitro.

Cancer risk in patients with type 2 diabetes mellitus and their relatives

Epidemiological studies indicate that risks of certain cancers are increased in individuals hospitalized for type 2 diabetes mellitus (T2DM), which may not be representative of the entire population of T2DM patients as most of them are treated in primary health cares. To examine the subsequent cancer risk in individuals with T2DM from hospitals and primary health cares, and in their siblings and spouses, standardized incidence ratios (SIRs) were used to assess systematically risks of 35 cancer sites/types in individuals with T2DM using a nationwide Swedish database covering the period 1964 through 2010. Increased SIRs were recorded for 24 cancer sites/types in individuals with T2DM. The highest SIRs were for pancreatic cancer and liver cancer (2.98 and 2.43, respectively). A decreased SIR was noted for prostate cancer. Five cancers showed increased SIRs during the whole follow-up period: colon, liver, pancreatic, endometrial and kidney cancers. T2DM patients in inpatient, outpatient and primary health care showed similar risk patterns. The overall SIRs for cancer in the siblings and spouses of individuals with T2DM were 0.97 and 1.01, respectively. The insulin users showed an overall increased risk of cancer. This study showed increased risks of 24 cancers in individuals with T2DM, but not in their siblings or spouses, suggesting that the profound metabolic disturbances of the underlying disease may explain the observed increases. Further studies examining the endogenous and exogenous factors underlying these associations are needed.

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.

Metabolic syndrome in the development and progression of prostate cancer

Prostate cancer (PCa) is the most common noncutaneous malignancy and second leading cause of cancer-specific mortality for men in the United States. There is a wide spectrum of aggressiveness ranging from biologically significant to indolent disease, which has led to an interest in the identification of risk factors for its development and progression. Emerging evidence has suggested an association between metabolic syndrome (MetS) and PCa. MetS represents a cluster of metabolic derangements that confer an increased risk of cardiovascular disease and type 2 diabetes mellitus. Its individual components include obesity, dyslipidemias, high blood pressure, and high fasting glucose levels. MetS has become pervasive and is currently associated with a high socioeconomic cost in both industrialized and developing countries throughout the world. The relationship between MetS and PCa is complex and yet to be fully defined. A better understanding of this relationship will facilitate the development of novel therapeutic targets for the prevention of PCa and improvement of outcomes among diagnosed men in the future. In this review, we evaluate the current evidence on the role of MetS in the development and progression of PCa. We also discuss the clinical implications on the management of PCa and consider the future direction of this subject.

Gene-Lifestyle Interactions in Complex Diseases: Design and Description of the GLACIER and VIKING Studies

Most complex diseases have well-established genetic and non-genetic risk factors. In some instances, these risk factors are likely to interact, whereby their joint effects convey a level of risk that is either significantly more or less than the sum of these risks. Characterizing these gene-environment interactions may help elucidate the biology of complex diseases, as well as to guide strategies for their targeted prevention. In most cases, the detection of gene-environment interactions will require sample sizes in excess of those needed to detect the marginal effects of the genetic and environmental risk factors. Although many consortia have been formed, comprising multiple diverse cohorts to detect gene-environment interactions, few robust examples of such interactions have been discovered. This may be because combining data across studies, usually through meta-analysis of summary data from the contributing cohorts, is often a statistically inefficient approach for the detection of gene-environment interactions. Ideally, single, very large and well-genotyped prospective cohorts, with validated measures of environmental risk factor and disease outcomes should be used to study interactions. The presence of strong founder effects within those cohorts might further strengthen the capacity to detect novel genetic effects and gene-environment interactions. Access to accurate genealogical data would also aid in studying the diploid nature of the human genome, such as genomic imprinting (parent-of-origin effects). Here we describe two studies from northern Sweden (the GLACIER and VIKING studies) that fulfill these characteristics.

Poor glycemic control of diabetes mellitus is associated with higher risk of prostate cancer detection in a biopsy population

OBJECTIVES

To evaluate the impact of glycemic control of diabetes mellitus (DM) on prostate cancer detection in a biopsy population.

PATIENTS AND METHODS

We retrospectively reviewed the records of 1,368 men who underwent prostate biopsy at our institution. We divided our biopsy population into three groups according to their history of DM, and their Hemoglobin A1c (HbA1c) level: a no-DM (DM-) group; a good glycemic control (DM+GC) group (HbA1c <6.5%); and a poor glycemic control (DM+PC) group (HbA1c ≥6.5%). For sub-analyses, the DM+PC group was divided into a moderately poor glycemic control (DM+mPC) group (6.5≤ HbA1c <7.5%) and a severely poor glycemic control (DM+sPC) group (HbA1c ≥7.5%).

RESULTS

Among 1,368 men, 338 (24.7%) had a history of DM, and 393 (28.7%) had a positive biopsy. There was a significant difference in prostatic specific antigen density (PSAD) (P = 0.037) and the frequency of abnormal DRE findings (P = 0.031) among three groups. The occurrence rate of overall prostate cancer (P<0.001) and high-grade prostate cancer (P = 0.016) also presented with a significantly difference. In the multivariate analysis, the DM+PC group was significantly associated with a higher rate of overall prostate cancer detection in biopsy subjects compared to the DM- group (OR = 2.313, P = 0.001) but the DM+PC group was not associated with a higher rate of high-grade (Gleason score ≥7) diseases detected during the biopsy (OR = 1.297, P = 0.376). However, in subgroup analysis, DM+sPC group was significantly related to a higher risk of high-grade diseases compared to the DM- group (OR = 2.446, P = 0.048).

CONCLUSIONS

Poor glycemic control of DM was associated with a higher risk of prostate cancer detection, including high-grade disease, in the biopsy population.

Shared common variants in prostate cancer and blood lipids

BACKGROUND

Epidemiological and clinical studies suggest comorbidity between prostate cancer (PCA) and cardiovascular disease (CVD) risk factors. However, the relationship between these two phenotypes is still not well understood. Here we sought to identify shared genetic loci between PCA and CVD risk factors.

METHODS

We applied a genetic epidemiology method based on conjunction false discovery rate (FDR) that combines summary statistics from different genome-wide association studies (GWAS), and allows identification of genetic overlap between two phenotypes. We evaluated summary statistics from large, multi-centre GWA studies of PCA (n=50 000) and CVD risk factors (n=200 000) [triglycerides (TG), low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol, systolic blood pressure, body mass index, waist-hip ratio and type 2 diabetes (T2D)]. Enrichment of single nucleotide polymorphisms (SNPs) associated with PCA and CVD risk factors was assessed with conditional quantile-quantile plots and the Anderson-Darling test. Moreover, we pinpointed shared loci using conjunction FDR.

RESULTS

We found the strongest enrichment of P-values in PCA was conditional on LDL and conditional on TG. In contrast, we found only weak enrichment conditional on HDL or conditional on the other traits investigated. Conjunction FDR identified altogether 17 loci; 10 loci were associated with PCA and LDL, 3 loci were associated with PCA and TG and additionally 4 loci were associated with PCA, LDL and TG jointly (conjunction FDR <0.01). For T2D, we detected one locus adjacent to HNF1B.

CONCLUSIONS

We found polygenic overlap between PCA predisposition and blood lipids, in particular LDL and TG, and identified 17 pleiotropic gene loci between PCA and LDL, and PCA and TG, respectively. These findings provide novel pathobiological insights and may have implications for trials using targeting lipid-lowering agents in a prevention or cancer setting.

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.

No association of plasma levels of adiponectin and c-peptide with risk of aggressive prostate cancer in the Cancer Prevention Study II Nutrition Cohort

BACKGROUND

Obesity is associated with a higher risk of aggressive prostate cancer and alters circulating levels of insulin and adiponectin, two hormones that influence biologic processes implicated in carcinogenesis. Results of some studies showed associations of circulating levels of adiponectin, insulin, and c-peptide (a marker of insulin secretion) with aggressive prostate cancer, but the size of these studies was limited.

METHODS

A nested case-control study of 272 aggressive prostate cancer cases [Gleason score ≥ 7 (4+3) or T3-T4] and 272 age- and race-matched controls from the Cancer Prevention Study II Nutrition Cohort was conducted to determine the associations of prediagnostic plasma levels of c-peptide and adiponectin with risk of aggressive prostate cancer.

RESULTS

Neither circulating adiponectin nor c-peptide was associated with risk of aggressive prostate cancer. In analyses of the highest-risk aggressive prostate cancer (Gleason score ≥ 8 or T3-T4), the highest quartile of c-peptide, compared with the lowest, was associated with an OR of 1.41 [95% confidence interval (CI), 0.72-2.78].

CONCLUSIONS

Our findings provide no support for the hypothesis that adiponectin is associated with risk of aggressive prostate cancer but a possible association of high levels of c-peptide with particularly high-risk prostate cancer cannot be ruled out.

IMPACT

These results indicate that changes in circulating levels of adiponectin and c-peptide do not play an important role in risk of aggressive prostate cancer.

Diabetes and cancer: two diseases with obesity as a common risk factor

There is a growing body of evidence to support a connection between diabetes (predominantly type 2), obesity and cancer. Multiple meta-analyses of epidemiological data show that people with diabetes are at increased risk of developing many different types of cancers, along with an increased risk of cancer mortality. Several pathophysiological mechanisms for this relationship have been postulated, including insulin resistance and hyperinsulinaemia, enhanced inflammatory processes, dysregulation of sex hormone production and hyperglycaemia. In addition to these potential mechanisms, a number of common risk factors, including obesity, may be behind the association between diabetes and cancer. Indeed, obesity is associated with an increased risk of cancer and diabetes. Abdominal adiposity has been shown to play a role in creating a systemic pro-inflammatory environment, which could result in the development of both diabetes and cancer. Here, we examine the relationship between diabetes, obesity and cancer, and investigate the potential underlying causes of increased cancer risk in individuals with diabetes. Current treatment recommendations for reducing the overall disease burden are also explored and possible areas for future research are considered.

Epithelial cancers in the post-genomic era: should we reconsider our lifestyle?

The age-related epithelial cancers of the breast, colorectum and prostate are the most prevalent and are increasing in our aging populations. Epithelial cells turnover rapidly and mutations naturally accumulate throughout life. Most epithelial cancers arise from this normal mutation rate. All elderly individuals will harbour many cells with the requisite mutations and most will develop occult neoplastic lesions. Although essential for initiation, these mutations are not sufficient for the progression of cancer to a life-threatening disease. This progression appears to be dependent on context: the tissue ecosystem within individuals and lifestyle exposures across populations of individuals. Together, this implies that the seeds may be plentiful but they only germinate in the right soil. The incidence of these cancers is much lower in Eastern countries but is increasing with Westernisation and increases more acutely in migrants to the West. A Western lifestyle is strongly associated with perturbed metabolism, as evidenced by the epidemics of obesity and diabetes: this may also provide the setting enabling the progression of epithelial cancers. Epidemiology has indicated that metabolic biomarkers are prospectively associated with cancer incidence and prognosis. Furthermore, within cancer research, there has been a rediscovery that a switch in cell metabolism is critical for cancer progression but this is set within the metabolic status of the host. The seed may only germinate if the soil is fertile. This perspective brings together the different avenues of investigation implicating the role that metabolism may play within the context of post-genomic concepts of cancer.

The association between self-reported diabetes and cancer incidence in the NIH-AARP Diet and Health Study

CONTEXT

Epidemiological studies have observed associations between diabetes and a number of different cancers. Yet the association with cancer overall and the interrelationship of diabetes and obesity with cancer have been unclear. OBJECTIVE, DESIGN, SETTING, AND PARTICIPANTS: We evaluated the association between self-reported diabetes and cancer incidence in the NIH-AARP (National Institutes of Health-American Association of Retired Persons) Diet and Health Study, a prospective cohort in which 295,276 men and 199,591 women completed a questionnaire in 1995-1996 and were followed up for cancer through 2006.

MAIN OUTCOME MEASURES

Hazard ratios (HRs) and 95% confidence intervals (CIs) for cancer incidence, overall and by type, were estimated from multivariate Cox proportional hazards models.

RESULTS

Diabetes was positively associated with total incident cancer in women (1.07, 95% CI 1.02-1.12) but inversely in men (0.96, 95% CI 0.93-0.98). However, diabetes was inversely associated with prostate cancer (HR 0.74, 95% CI 0.70-0.78), which constituted 42% of cancers in men. After excluding prostate cancer, diabetes was also positively associated with cancer in men (HR 1.09, 95% CI 1.04-1.14). By site, diabetes was positively associated with anal, bladder, colon, kidney, liver, pancreatic, rectal, and stomach cancers and in women with endometrial cancer. We also evaluated the joint effect of obesity and diabetes and observed that diabetes conferred additional risk, beyond that of overweight or obesity, for cancer overall, excluding prostate, and for certain sites including the bladder, colon, endometrium, kidney, liver, pancreas, rectum, and stomach.

CONCLUSION

Our results suggest an etiological role for diabetes in a number of cancers, independent of obesity, and that preventing diabetes may contribute to reduced cancer risk.