Circulating insulin-like growth factors and IGF-binding proteins in PSA-detected prostate cancer: the large case-control study ProtecT

Insulin-related traits and prostate cancer: A Mendelian randomization study

Investigating the causal relationship between insulin secretion and prostate cancer (PCa) development is challenging due to the multifactorial nature of PCa, which complicates the isolation of the specific impact of insulin-related factors. We conducted a Mendelian randomization (MR) study to investigate the associations between insulin secretion-related traits and PCa. We used 36, 60, 56, 23, 48, and 49 single nucleotide polymorphisms (SNPs) as instrumental variables for fasting insulin, insulin sensitivity, proinsulin, and proinsulin in nondiabetic individuals, individuals with diabetes, and individuals receiving exogenous insulin, respectively. These SNPs were selected from various genome-wide association studies. To clarify the causal relationship between insulin-related traits and PCa, we utilized a multivariable MR analysis to adjust for obesity and body fat percentage. Additionally, two-step Mendelian randomization was conducted to assess the role of insulin-like growth factor 1 (IGF-1) in the relationship between proinsulin and PCa. Two-sample MR analysis revealed strong associations between genetically predicted fasting insulin, insulin sensitivity, proinsulin, and proinsulin in nondiabetic individuals and the development of PCa. After adjustment for obesity and body fat percentage using multivariable MR analysis, proinsulin remained significantly associated with PCa, whereas other factors were not. Furthermore, two-step MR analysis demonstrated that proinsulin acts as a negative factor in prostate carcinogenesis, largely independent of IGF-1. This study provides evidence suggesting that proinsulin may act as a negative factor contributing to the development of PCa. Novel therapies targeting proinsulin may have potential benefits for PCa patients, potentially reducing the need for unnecessary surgical treatments.

The Potential of Extracellular Matrix- and Integrin Adhesion Complex-Related Molecules for Prostate Cancer Biomarker Discovery

Prostate cancer is among the top five cancer types according to incidence and mortality. One of the main obstacles in prostate cancer management is the inability to foresee its course, which ranges from slow growth throughout years that requires minimum or no intervention to highly aggressive disease that spreads quickly and resists treatment. Therefore, it is not surprising that numerous studies have attempted to find biomarkers of prostate cancer occurrence, risk stratification, therapy response, and patient outcome. However, only a few prostate cancer biomarkers are used in clinics, which shows how difficult it is to find a novel biomarker. Cell adhesion to the extracellular matrix (ECM) through integrins is among the essential processes that govern its fate. Upon activation and ligation, integrins form multi-protein intracellular structures called integrin adhesion complexes (IACs). In this review article, the focus is put on the biomarker potential of the ECM- and IAC-related molecules stemming from both body fluids and prostate cancer tissue. The processes that they are involved in, such as tumor stiffening, bone turnover, and communication via exosomes, and their biomarker potential are also reviewed.

The Causal Relationships Between Extrinsic Exposures and Risk of Prostate Cancer: A Phenome-Wide Mendelian Randomization Study

Background

Prostate cancer is the second most common cancer in males worldwide, and multitudes of factors have been reported to be associated with prostate cancer risk.

Objectives

We aim to conduct the phenome-wide exposed-omics analysis of the risk factors for prostate cancer and verify the causal associations between them.

Methods

We comprehensively searched published systematic reviews and meta-analyses of cohort studies and conducted another systematic review and meta-analysis of the Mendelian randomization studies investigating the associations between extrinsic exposures and prostate cancer, thus to find all of the potential risk factors for prostate cancer. Then, we launched a phenome-wide two-sample Mendelian randomization analysis to validate the potentially causal relationships using the PRACTICAL consortium and UK Biobank.

Results

We found a total of 55 extrinsic exposures for prostate cancer risk. The causal effect of 30 potential extrinsic exposures on prostate cancer were assessed, and the results showed docosahexaenoic acid (DHA) [odds ratio (OR)=0.806, 95% confidence interval (CI): 0.661-0.984, p=0.034], insulin-like growth factor binding protein 3 (IGFBP-3) (OR=1.0002, 95%CI: 1.00004-1.0004, p=0.016), systemic lupus erythematosus (SLE) (OR=0.9993, 95%CI: 0.9986-0.99997, p=0.039), and body mass index (BMI) (OR=0.995, 95%CI: 0.990-0.9999, p=0.046) were associated with prostate cancer risk. However, no association was found between the other 26 factors and prostate cancer risk.

Conclusions

Our study discovered the phenome-wide exposed-omics risk factors profile of prostate cancer, and verified that the IGFBP-3, DHA, BMI, and SLE were causally related to prostate cancer risk. The results may provide new insight into the study of the pathogenesis of prostate cancer.

Comparison of the difference in serum insulin growth factor-1 levels between chronological age and bone age among children

OBJECTIVE

By measuring serum insulin-like growth factor-1 (IGF-1) levels in children aged 2-16, we aimed to analyze the changes in IGF-1 levels in different sex and age groups, and compare the consistency of IGF-1 results evaluated by chronological age (CA) and bone age (BA) in children.

METHODS

A cross-sectional study was conducted between January 2017 and December 2020 among 2979 relatively healthy children who attended the Department of Growth and Development outpatient clinic and health care center of the Affiliated Children's Hospital of the Capital Institute of Pediatrics and underwent health examination and development assessment. Height, weight, and Tanner pubertal stage were measured by pediatricians. The CHN method was used to estimate BA. Venous blood samples were collected from the children, and IGF-1 levels were determined via chemiluminescence.

RESULTS

IGF-1 levels in childhood increased slowly with age, dramatically during puberty,and continuously withgrowth until to 15 years for boys and reached a peak value at 13 years for girls based on CA. IGF-1 levels reached peak values at 14 and 13 years for boys and girls, respectively, based on BA. There were differences in IGF-1 values between the CA and BA groups at the age of 10-11 years for boys and 7-11 years for girls. A total of 103 boys (7.7%) and 17 girls (1.0%) had IGF-1 levels below the lower limit of the reference range based on CA; evaluating based on BA, there were 82 boys (6.1%) and 15 girls (0.9%) still had IGF-1 values less than the lower limit of the reference range. Eighteen boys (1.3%) and 173 girls (10.5%) had IGF-1 levels above the upper limit of the reference range based on CA; evaluating based on BA, these numbers reduced to 5 (0.4%) among boys and 41 (2.5%) among girls.

CONCLUSIONS

There is a significant difference between BA and CA in evaluating IGF-1 levels in children, which can significantly reduce the proportion of IGF-1 values above the upper limit of the kit reference range in children. This suggests that children with BA advanced in pubertal period, the evaluating results of IGF-1 should be corrected by using BA.

The Roles of Insulin-Like Growth Factor Binding Protein Family in Development and Diseases

The insulin-like growth factor (IGF) system comprises ligands of IGF-I/II, IGF receptors (IGFR), IGF binding proteins (IGFBPs), and IGFBP hydrolases. The IGF system plays multiple roles during various disease development as IGFs are widely involved in cell proliferation and differentiation through regulating DNA transcription. Meanwhile, IGFBPs, which are mainly synthesized in the liver, can bind to IGFs and perform two different functions: either inhibition of IGFs by forming inactive compounds with IGF or enhancement of the function of IGFs by strengthening the IGF-IGFR interaction. Interestingly, IGFBPs may have wider functions through IGF-independent mechanisms. Studies have shown that IGFBPs play important roles in cardiovascular disease, tumor progression, fetal growth, and neuro-nutrition. In this review, we emphasize that different IGFBP family members have common or unique functions in numerous diseases; moreover, IGFBPs may serve as biomarkers for disease diagnosis and prediction.

Active monitoring, radical prostatectomy and radical radiotherapy in PSA-detected clinically localised prostate cancer: the ProtecT three-arm RCT

BACKGROUND

Prostate cancer is the most common cancer among men in the UK. Prostate-specific antigen testing followed by biopsy leads to overdetection, overtreatment as well as undertreatment of the disease. Evidence of treatment effectiveness has lacked because of the paucity of randomised controlled trials comparing conventional treatments.

OBJECTIVES

To evaluate the effectiveness of conventional treatments for localised prostate cancer (active monitoring, radical prostatectomy and radical radiotherapy) in men aged 50-69 years.

DESIGN

A prospective, multicentre prostate-specific antigen testing programme followed by a randomised trial of treatment, with a comprehensive cohort follow-up.

SETTING

Prostate-specific antigen testing in primary care and treatment in nine urology departments in the UK.

PARTICIPANTS

Between 2001 and 2009, 228,966 men aged 50-69 years received an invitation to attend an appointment for information about the Prostate testing for cancer and Treatment (ProtecT) study and a prostate-specific antigen test; 82,429 men were tested, 2664 were diagnosed with localised prostate cancer, 1643 agreed to randomisation to active monitoring (n = 545), radical prostatectomy (n = 553) or radical radiotherapy (n = 545) and 997 chose a treatment.

INTERVENTIONS

The interventions were active monitoring, radical prostatectomy and radical radiotherapy.

TRIAL PRIMARY OUTCOME MEASURE

Definite or probable disease-specific mortality at the 10-year median follow-up in randomised participants.

SECONDARY OUTCOME MEASURES

Overall mortality, metastases, disease progression, treatment complications, resource utilisation and patient-reported outcomes.

RESULTS

There were no statistically significant differences between the groups for 17 prostate cancer-specific (p = 0.48) and 169 all-cause (p = 0.87) deaths. Eight men died of prostate cancer in the active monitoring group (1.5 per 1000 person-years, 95% confidence interval 0.7 to 3.0); five died of prostate cancer in the radical prostatectomy group (0.9 per 1000 person-years, 95% confidence interval 0.4 to 2.2 per 1000 person years) and four died of prostate cancer in the radical radiotherapy group (0.7 per 1000 person-years, 95% confidence interval 0.3 to 2.0 per 1000 person years). More men developed metastases in the active monitoring group than in the radical prostatectomy and radical radiotherapy groups: active monitoring, n = 33 (6.3 per 1000 person-years, 95% confidence interval 4.5 to 8.8); radical prostatectomy, n = 13 (2.4 per 1000 person-years, 95% confidence interval 1.4 to 4.2 per 1000 person years); and radical radiotherapy, n = 16 (3.0 per 1000 person-years, 95% confidence interval 1.9 to 4.9 per 1000 person-years; p = 0.004). There were higher rates of disease progression in the active monitoring group than in the radical prostatectomy and radical radiotherapy groups: active monitoring (n = 112; 22.9 per 1000 person-years, 95% confidence interval 19.0 to 27.5 per 1000 person years); radical prostatectomy (n = 46; 8.9 per 1000 person-years, 95% confidence interval 6.7 to 11.9 per 1000 person-years); and radical radiotherapy (n = 46; 9.0 per 1000 person-years, 95% confidence interval 6.7 to 12.0 per 1000 person years; p < 0.001). Radical prostatectomy had the greatest impact on sexual function/urinary continence and remained worse than radical radiotherapy and active monitoring. Radical radiotherapy's impact on sexual function was greatest at 6 months, but recovered somewhat in the majority of participants. Sexual and urinary function gradually declined in the active monitoring group. Bowel function was worse with radical radiotherapy at 6 months, but it recovered with the exception of bloody stools. Urinary voiding and nocturia worsened in the radical radiotherapy group at 6 months but recovered. Condition-specific quality-of-life effects mirrored functional changes. No differences in anxiety/depression or generic or cancer-related quality of life were found. At the National Institute for Health and Care Excellence threshold of £20,000 per quality-adjusted life-year, the probabilities that each arm was the most cost-effective option were 58% (radical radiotherapy), 32% (active monitoring) and 10% (radical prostatectomy).

LIMITATIONS

A single prostate-specific antigen test and transrectal ultrasound biopsies were used. There were very few non-white men in the trial. The majority of men had low- and intermediate-risk disease. Longer follow-up is needed.

CONCLUSIONS

At a median follow-up point of 10 years, prostate cancer-specific mortality was low, irrespective of the assigned treatment. Radical prostatectomy and radical radiotherapy reduced disease progression and metastases, but with side effects. Further work is needed to follow up participants at a median of 15 years.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN20141297.

FUNDING

This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 37. See the National Institute for Health Research Journals Library website for further project information.

The role of insulin-like growth factors in the development of prostate cancer

INTRODUCTION

Preclinical, clinical, and population studies have provided robust evidence for an important role for the insulin-like growth factor (IGF) system in the development of prostate cancer.

AREAS COVERED

An overview of the IGF system is provided. The evidence implicating the IGF system in the development of prostate cancer is summarized. The compelling evidence culminated in a number of clinical trials of agents targeting the system; the reasons for the failure of these trials are discussed.

EXPERT OPINION

Clinical trials of agents targeting the IGF system in prostate cancer were terminated due to limited objective clinical responses and are unlikely to be resumed unless a convincing predictive biomarker is identified that would enable the selection of likely responders. The aging population and increased screening will lead to greater diagnosis of prostate cancer. Although the vast majority will be indolent disease, the epidemics of obesity and diabetes will increase the proportion that progress to clinical disease. The increased population of worried men will result in more trials aimed to reduce the risk of disease progression; actual clinical endpoints will be challenging and the IGFs remain the best intermediate biomarkers to indicate a response that could alter the course of disease.

Harnessing the potential of multimodal radiotherapy in prostate cancer

Radiotherapy in combination with androgen deprivation therapy (ADT) is a standard treatment option for men with localized and locally advanced prostate cancer. However, emerging clinical evidence suggests that radiotherapy can be incorporated into multimodality therapy regimens beyond ADT, in combinations that include chemotherapy, radiosensitizing agents, immunotherapy and surgery for the treatment of men with localized and locally advanced prostate cancer, and those with oligometastatic disease, in whom the low metastatic burden in particular might be treatable with these combinations. This multimodal approach is increasingly recognized as offering considerable clinical benefit, such as increased antitumour effects and improved survival. Thus, radiotherapy is becoming a key component of multimodal therapy for many stages of prostate cancer, particularly oligometastatic disease.

Systemic Metabolism, Its Regulators, and Cancer: Past Mistakes and Future Potential

There has been a resurgence of interest in cancer metabolism; primarily in the resetting of metabolism within malignant cells. Metabolism within cells has always been a tightly regulated process; initially in protozoans due to metabolic enzymes, and the intracellular signaling pathways that regulate these, being directly sensitive to the availability of nutrients. With the evolution of metazoans many of these controls had been overlaid by extra-cellular regulators that ensured coordinated regulation of metabolism within the community of cells that comprised the organism. Central to these systemic regulators is the insulin/insulin-like growth factor (IGF) system that throughout evolution has integrated the control of tissue growth with metabolic status. Oncological interest in the main systemic metabolic regulators greatly subsided when pharmaceutical strategies designed to treat cancers failed in the clinic. During the same period, however the explosion of new information from genetics has revealed the complexity and heterogeneity of advanced cancers and helped explain the problems of managing cancer when it reaches such a stage. Evidence has also accumulated implying that the setting of the internal environment determines whether cancers progress to advanced disease and metabolic status is clearly an important component of this local ecology. We are in the midst of an epidemic of metabolic disorders and there is considerable research into strategies for controlling metabolism. Integrating these new streams of information suggests new possibilities for cancer prevention; both primary and secondary.

Reassessing the Association between Circulating Vitamin D and IGFBP-3: Observational and Mendelian Randomization Estimates from Independent Sources

BACKGROUND

Circulating insulin-like growth factor binding protein 3 (IGFBP-3) has been associated with prostate cancer. Preclinical studies found that vitamin D regulates IGFBP-3 expression, although evidence from epidemiologic studies is conflicting.

METHODS

Mendelian randomization analyses (MR) were conducted to reassess associations between IGFBP-3 and prostate cancer risk and advanced prostate cancer using summary statistics from the PRACTICAL consortium (44,825 cases; 27,904 controls). Observational and MR analyses were conducted to assess the relationship between inactive vitamin D [25(OH)D] and IGFBP-3 using data from the ProtecT study (1,366 cases;1,071 controls) and summary statistics from the CHARGE consortium (n = 18,995).

RESULTS

The OR for prostate cancer per SD unit increase in circulating IGFBP-3 was 1.14 [95% confidence interval (CI), 1.02-1.28]. The OR for advanced prostate cancer per SD unit increase in IGFBP-3 was 1.22 (95% CI, 1.07-1.40). Observationally, a SD increase in 25(OH)D was associated with a 0.1SD (95% CI, 0.05-0.14) increase in IGFBP-3. MR analyses found little evidence for a causal relationship between circulating 25(OH)D and IGFBP-3 in the circulation.

CONCLUSIONS

This study provided confirmatory evidence that IGFBP-3 is a risk factor for prostate cancer risk and progression. Observationally, there was evidence that 25(OH)D is associated with IGFBP-3, but MR analyses suggested that these findings were unlikely to be causal. Findings may be limited by the nature of instrumentation of 25(OH)D and IGFBP-3 and the utility of circulating measures. 25(OH)D appears unlikely to be causally related to IGFBP-3 in the circulation, however, our findings do not preclude causal associations at the tissue level.

IMPACT

IGFBP-3 is a prostate cancer risk factor but 25(OH)D are unlikely to be causally related to IGFBP-3 in the circulation.

Metabolic syndrome, endocrine disruptors and prostate cancer associations: biochemical and pathophysiological evidences

This review summarizes the main pathophysiological basis of the relationship between metabolic syndrome, endocrine disruptor exposure and prostate cancer that is the most common cancer among men in industrialized countries. Metabolic syndrome is a cluster of metabolic and hormonal factors having a central role in the initiation and recurrence of many western chronic diseases including hormonal-related cancers and it is considered as the worlds leading health problem in the coming years. Many biological factors correlate metabolic syndrome to prostate cancer and this review is aimed to focus, principally, on growth factors, cytokines, adipokines, central obesity, endocrine abnormalities and exposure to specific endocrine disruptors, a cluster of chemicals, to which we are daily exposed, with a hormone-like structure influencing oncogenes, tumor suppressors and proteins with a key role in metabolism, cell survival and chemo-resistance of prostate cancer cells. Finally, this review will analyze, from a molecular point of view, how specific foods could reduce the relative risk of incidence and recurrence of prostate cancer or inhibit the biological effects of endocrine disruptors on prostate cancer cells. On the basis of these considerations, prostate cancer remains a great health problem in terms of incidence and prevalence and interventional studies based on the treatment of metabolic syndrome in cancer patients, minimizing exposure to endocrine disruptors, could be a key point in the overall management of this disease.

Post-diagnosis serum insulin-like growth factors in relation to dietary and lifestyle changes in the Prostate testing for cancer and Treatment (ProtecT) trial

PURPOSE

The insulin-like growth factor (IGF) system is modifiable by diet and lifestyle, and has been linked to prostate cancer development and progression.

METHODS

We conducted a prospective cohort study of 621 men diagnosed with localized prostate cancer to investigate the associations of dietary and lifestyle changes with post-diagnosis circulating levels of IGF-I and IGFBP-3. We used analysis of covariance to estimate the associations, controlling for baseline IGF-I or IGFBP-3, respectively.

RESULTS

Mean IGF-I levels were 6.5% (95% CI -12.8, -0.3%, p = 0.04) lower in men who decreased their protein intake after diagnosis compared to men who did not change. Men who changed their fruit and vegetable intake had lower IGF-I levels compared to non-changers [Decreased intake: -10.1%, 95% CI -18.4, -1.8%, p = 0.02; Increased intake: -12.0%, 95% CI -18.4, -1.8%, p = 0.002]. IGFBP-3 was 14.6% (95% CI -24.5, -4.8%, p = 0.004) lower in men who achieved a healthy body mass index after diagnosis. Men who became inactive had 9.5% higher average IGF-I levels (95% CI 0.1, 18.9%, p = 0.05).

CONCLUSIONS

Decreased protein intake and body mass index, and increased physical activity and fruit and vegetable intake, following a prostate cancer diagnosis were associated with reduced post-diagnosis serum IGF-I and IGFBP-3. Counterintuitively, reduced fruit and vegetable intake was also associated with reduced IGF-I, but with weak statistical support, possibly implicating chance. If confirmed in other studies, our findings may inform potential lifestyle interventions in prostate cancer. ProtecT was registered at International Standard Randomised Controlled Trial Registry, http://isrctn.org as ISRCTN20141297.

Does milk intake promote prostate cancer initiation or progression via effects on insulin-like growth factors (IGFs)? A systematic review and meta-analysis

PURPOSE

To establish whether the association between milk intake and prostate cancer operates via the insulin-like growth factor (IGF) pathway (including IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3).

METHODS

Systematic review, collating data from all relevant studies examining associations of milk with IGF, and those examining associations of IGF with prostate cancer risk and progression. Data were extracted from experimental and observational studies conducted in either humans or animals, and analyzed using meta-analysis where possible, with summary data presented otherwise.

RESULTS

One hundred and seventy-two studies met the inclusion criteria: 31 examining the milk-IGF relationship; 132 examining the IGF-prostate cancer relationship in humans; and 10 animal studies examining the IGF-prostate cancer relationship. There was moderate evidence that circulating IGF-I and IGFBP-3 increase with milk (and dairy protein) intake (an estimated standardized effect size of 0.10 SD increase in IGF-I and 0.05 SD in IGFBP-3 per 1 SD increase in milk intake). There was moderate evidence that prostate cancer risk increased with IGF-I (Random effects meta-analysis OR per SD increase in IGF-I 1.09; 95% CI 1.03, 1.16; n = 51 studies) and decreased with IGFBP-3 (OR 0.90; 0.83, 0.98; n = 39 studies), but not with other growth factors. The IGFBP-3 -202A/C single nucleotide polymorphism was positively associated with prostate cancer (pooled OR for A/C vs. AA = 1.22; 95% CI 0.84, 1.79; OR for C/C vs. AA = 1.51; 1.03, 2.21, n = 8 studies). No strong associations were observed for IGF-II, IGFBP-1 or IGFBP-2 with either milk intake or prostate cancer risk. There was little consistency within the data extracted from the small number of animal studies. There was additional evidence to suggest that the suppression of IGF-II can reduce tumor size, and contradictory evidence with regards to the effect of IGFBP-3 suppression on tumor progression.

CONCLUSION

IGF-I is a potential mechanism underlying the observed associations between milk intake and prostate cancer risk.

Prediagnostic circulating concentrations of plasma insulin-like growth factor-I and risk of lymphoma in the European Prospective Investigation into Cancer and Nutrition

Insulin-like growth factor (IGF)-I has cancer promoting activities. However, the hypothesis that circulating IGF-I concentration is related to risk of lymphoma overall or its subtypes has not been examined prospectively. IGF-I concentration was measured in pre-diagnostic plasma samples from a nested case-control study of 1,072 cases of lymphoid malignancies and 1,072 individually matched controls from the European Prospective Investigation into Cancer and Nutrition. Odds ratios (ORs) and confidence intervals (CIs) for lymphoma were calculated using conditional logistic regression. IGF-I concentration was not associated with overall lymphoma risk (multivariable-adjusted OR for highest versus lowest third = 0.77 [95% CI = 0.57-1.03], ptrend  = 0.06). There was no statistical evidence of heterogeneity in this association with IGF-I by sex, age at blood collection, time between blood collection and diagnosis, age at diagnosis, or body mass index (pheterogeneity for all  ≥ 0.05). There were no associations between IGF-I concentration and risk for specific BCL subtypes, T-cell lymphoma or Hodgkin lymphoma, although number of cases were small. In this European population, IGF-I concentration was not associated with risk of overall lymphoma. This study provides the first prospective evidence on circulating IGF-I concentrations and risk of lymphoma. Further prospective data are required to examine associations of IGF-I concentrations with lymphoma subtypes.

The role of IGF-1 and the distribution of body fat in decreasing the number of prostate rebiopsies

OBJECTIVE

To assess the usefulness of IGF-1 and internal organ fat measured by bioelectrical impedance audiometry to avoid rebiopsies in patients with persistently high prostate-specific antigen (PSA) levels.

MATERIAL AND METHOD

A prospective study was conducted with 92 patients who underwent prostate rebiopsy due to high PSA levels with negative results in the rectal examination and a lack of preneoplastic lesions. The patients previously had their IGF-1 levels measured and had undergone an impedance audiometry test using the abdominal Fat Analyser AB-140 TANITA system. We calculated the receiver operating characteristic (ROC) curves for the PSA levels, %PSA, internal organ fat and IGF-1 and PSA density.

RESULTS

Twenty-five patients were diagnosed with prostate cancer. These patients had significantly higher PSA, PSAd and IGF-1 values and a tendency towards higher internal organ fat levels and lower %PSA readings (p=.001, p=.003, p=.001, p=.24 and P=0.28, respectively). The ROC curve showed an area under the curve for IGF-1 and PSA of .82 and .81, respectively. Using the cutoff points for 95% sensitivity and using the 3 criteria as an indication of rebiopsy, 74% of the biopsies would have been spared, leaving undiagnosed only 1 patient with clinically significant cancer -Gleason score>7 (4+3)-. The positive and negative predictive values for the set of variables were higher than for each one separately (PPV: 66/NPV: 63). The cost of both determinations was 82 euros.

CONCLUSIONS

Our results suggest that measuring IGF-1 could significantly decrease the number of unnecessary rebiopsies in an inexpensive and safe manner.

Controversies in the risk of neoplasia in GH deficiency

Growth hormone (GH) replacement in GH deficient (GHD) children secures normal linear growth, while in GHD adults it improves metabolic status, body composition and quality of life. Safety of GH treatment is an important issue in particular concerning the controversy of potential cancer risk. Unlike in congenital IGF-1 deficiency, there is no complete protection against cancer in GHD patients. Important modifiable risk factors in GHD patients are obesity, insulin resistance, sedentary behavior, circadian rhythm disruption, chronic low grade inflammation and concomitant sex hormone replacement. Age, family history, hereditary cancer predisposition syndromes or cranial irradiation may present non-modifiable risk factors. Quantifying the risk of cancer in relation to GH therapy in adult GHD patients is complex. There is evidence that links GH to cancer occurrence or promotion, but the evidence is progressively weaker when moving from in vitro studies to in vivo animal studies to epidemiological studies and finally to studies on GH treated patients. GH-IGF inhibition in experimental animals leads to decreased cancer incidence and progression. Epidemiological studies suggest an association of high normal circulating IGF-1 or GH to cancer incidence in general population. Data regarding cancer incidence in acromegaly are inconsistent but thyroid and colorectal neoplasias are the main source of concern. Replacement therapy with rhGH for GHD is generally safe. Overall the rate of de novo cancers was not increased in studies of GH-treated GHD patients. Additional caution is mandated in patients with history of cancer, strong family history of cancer and with advancing age. Childhood cancer survivors may be at increased risk for secondary neoplasms compared with general population. In this subgroup GH therapy should be used cautiously and with respect to other risk factors (cranial irradiation etc). We believe that the benefits of GH therapy against the morbidity of untreated GH deficiency outweigh the theoretical cancer risk. Proper monitoring of GH treatment with diligent cancer surveillance remains essential.

Assessing the role of insulin-like growth factors and binding proteins in prostate cancer using Mendelian randomization: Genetic variants as instruments for circulating levels

Circulating insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) are associated with prostate cancer. Using genetic variants as instruments for IGF peptides, we investigated whether these associations are likely to be causal. We identified from the literature 56 single nucleotide polymorphisms (SNPs) in the IGF axis previously associated with biomarker levels (8 from a genome-wide association study [GWAS] and 48 in reported candidate genes). In ∼700 men without prostate cancer and two replication cohorts (N ∼ 900 and ∼9,000), we examined the properties of these SNPS as instrumental variables (IVs) for IGF-I, IGF-II, IGFBP-2 and IGFBP-3. Those confirmed as strong IVs were tested for association with prostate cancer risk, low (< 7) vs. high (≥ 7) Gleason grade, localised vs. advanced stage, and mortality, in 22,936 controls and 22,992 cases. IV analysis was used in an attempt to estimate the causal effect of circulating IGF peptides on prostate cancer. Published SNPs in the IGFBP1/IGFBP3 gene region, particularly rs11977526, were strong instruments for IGF-II and IGFBP-3, less so for IGF-I. Rs11977526 was associated with high (vs. low) Gleason grade (OR per IGF-II/IGFBP-3 level-raising allele 1.05; 95% CI: 1.00, 1.10). Using rs11977526 as an IV we estimated the causal effect of a one SD increase in IGF-II (∼265 ng/mL) on risk of high vs. low grade disease as 1.14 (95% CI: 1.00, 1.31). Because of the potential for pleiotropy of the genetic instruments, these findings can only causally implicate the IGF pathway in general, not any one specific biomarker.

Is there an effect of ghrelin/ghrelin analogs on cancer? A systematic review

Ghrelin is a hormone with multiple physiologic functions, including promotion of growth hormone release, stimulation of appetite and regulation of energy homeostasis. Treatment with ghrelin/ghrelin-receptor agonists is a prospective therapy for disease-related cachexia and malnutrition. In vitro studies have shown high expression of ghrelin in cancer tissue, although its role including its impact in cancer risk and progression has not been established. We performed a systematic literature review to identify peer-reviewed human or animal in vivo original research studies of ghrelin, ghrelin-receptor agonists, or ghrelin genetic variants and the risk, presence, or growth of cancer using structured searches in PubMed database as well as secondary searches of article reference lists, additional reviews and meta-analyses. Overall, 45 (73.8%) of the 61 studies reviewed, including all 11 involving exogenous ghrelin/ghrelin-receptor agonist treatment, reported either a null (no statistically significant difference) or inverse association of ghrelin/ghrelin-receptor agonists or ghrelin genetic variants with cancer risk, presence or growth; 10 (16.7%) studies reported positive associations; and 6 (10.0%) reported both negative or null and positive associations. Differences in serum ghrelin levels in cancer cases vs controls (typically lower) were reported for some but not all cancers. The majority of in vivo studies showed a null or inverse association of ghrelin with risk and progression of most cancers, suggesting that ghrelin/ghrelin-receptor agonist treatment may have a favorable safety profile to use for cancer cachexia. Additional large-scale prospective clinical trials as well as basic bioscientific research are warranted to further evaluate the safety and benefits of ghrelin treatment in patients with cancer.

Insulin-like growth factor I and risk of incident cancer in elderly men - results from MrOS (Osteoporotic Fractures in Men) in Sweden

OBJECTIVE

Studies of the association between circulating IGF-I and cancer risk have shown conflicting results. We have previously observed a U-shaped association between IGF-I and cancer mortality. This study test the hypotheses of a U-shaped association between IGF-I and incident cancer.

DESIGN

Elderly men (2368), randomly recruited from the general community.

METHODS

IGF-I was measured in a cohort of elderly men. Complete data for incident cancer were obtained from the Swedish Cancer Registry. Statistical analyses included Cox proportional hazards regressions with or without a spline approach.

RESULTS

Three hundred and sixty-nine participants had incident cancer after baseline. Prostate cancer was most frequent (n = 140). There was no association between serum IGF-I and all cancer or prostate cancer incidence. However, there was a nonlinear association between IGF-I and nonprostate cancer incidence (P = <0·05). Exploratory analyses were performed for low and high serum IGF-I (quintiles 1 and 5) vs intermediate (quintiles 2-4, referent). There was a tendency of increased nonprostate cancer risk in men with high IGF-I (HR = 1·26, 95% confidence interval (CI): 0·92-1·71, P = 0·15). After excluding participants with follow-up of less than 2·6 years (half median follow-up time), to control for potential diagnostic delay, the association was statistically significant (HR = 1·55, CI: 1·03-2·35).

CONCLUSION

There was a significant nonlinear association between IGF-I and nonprostate cancer. No association between IGF-I and prostate cancer was observed. Future studies are warranted to further investigate this nonlinear association, including whether IGF-I concentration is a reproducible, and useful, risk marker of nonprostate cancer.

A Meta-analysis of Individual Participant Data Reveals an Association between Circulating Levels of IGF-I and Prostate Cancer Risk

The role of insulin-like growth factors (IGF) in prostate cancer development is not fully understood. To investigate the association between circulating concentrations of IGFs (IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3) and prostate cancer risk, we pooled individual participant data from 17 prospective and two cross-sectional studies, including up to 10,554 prostate cancer cases and 13,618 control participants. Conditional logistic regression was used to estimate the ORs for prostate cancer based on the study-specific fifth of each analyte. Overall, IGF-I, IGF-II, IGFBP-2, and IGFBP-3 concentrations were positively associated with prostate cancer risk (Ptrend all ≤ 0.005), and IGFBP-1 was inversely associated weakly with risk (Ptrend = 0.05). However, heterogeneity between the prospective and cross-sectional studies was evident (Pheterogeneity = 0.03), unless the analyses were restricted to prospective studies (with the exception of IGF-II, Pheterogeneity = 0.02). For prospective studies, the OR for men in the highest versus the lowest fifth of each analyte was 1.29 (95% confidence interval, 1.16-1.43) for IGF-I, 0.81 (0.68-0.96) for IGFBP-1, and 1.25 (1.12-1.40) for IGFBP-3. These associations did not differ significantly by time-to-diagnosis or tumor stage or grade. After mutual adjustment for each of the other analytes, only IGF-I remained associated with risk. Our collaborative study represents the largest pooled analysis of the relationship between prostate cancer risk and circulating concentrations of IGF-I, providing strong evidence that IGF-I is highly likely to be involved in prostate cancer development. Cancer Res; 76(8); 2288-300. ©2016 AACR.

Prostate cancer - evidence of exercise and nutrition trial (PrEvENT): study protocol for a randomised controlled feasibility trial

Background

A growing body of observational evidence suggests that nutritional and physical activity interventions are associated with beneficial outcomes for men with prostate cancer, including brisk walking, lycopene intake, increased fruit and vegetable intake and reduced dairy consumption. However, randomised controlled trial data are limited. The ‘Prostate Cancer: Evidence of Exercise and Nutrition Trial’ investigates the feasibility of recruiting and randomising men diagnosed with localised prostate cancer and eligible for radical prostatectomy to interventions that modify nutrition and physical activity. The primary outcomes are randomisation rates and adherence to the interventions at 6 months following randomisation. The secondary outcomes are intervention tolerability, trial retention, change in prostate specific antigen level, change in diet, change in general physical activity levels, insulin-like growth factor levels, and a range of related outcomes, including quality of life measures.

Methods/design

The trial is factorial, randomising men to both a physical activity (brisk walking or control) and nutritional (lycopene supplementation or increased fruit and vegetables with reduced dairy consumption or control) intervention. The trial has two phases: men are enrolled into a cohort study prior to radical prostatectomy, and then consented after radical prostatectomy into a randomised controlled trial. Data are collected at four time points (cohort baseline, true trial baseline and 3 and 6 months post-randomisation).

Discussion

The Prostate Cancer: Evidence of Exercise and Nutrition Trial aims to determine whether men with localised prostate cancer who are scheduled for radical prostatectomy can be recruited into a cohort and subsequently randomised to a 6-month nutrition and physical activity intervention trial. If successful, this feasibility trial will inform a larger trial to investigate whether this population will gain clinical benefit from long-term nutritional and physical activity interventions post-surgery.

Prostate Cancer: Evidence of Exercise and Nutrition Trial (PrEvENT) is registered on the ISRCTN registry, ref number ISRCTN99048944. Date of registration 17 November 2014.

The effects of height and BMI on prostate cancer incidence and mortality: a Mendelian randomization study in 20,848 cases and 20,214 controls from the PRACTICAL consortium

BACKGROUND

Epidemiological studies suggest a potential role for obesity and determinants of adult stature in prostate cancer risk and mortality, but the relationships described in the literature are complex. To address uncertainty over the causal nature of previous observational findings, we investigated associations of height- and adiposity-related genetic variants with prostate cancer risk and mortality.

METHODS

We conducted a case-control study based on 20,848 prostate cancers and 20,214 controls of European ancestry from 22 studies in the PRACTICAL consortium. We constructed genetic risk scores that summed each man's number of height and BMI increasing alleles across multiple single nucleotide polymorphisms robustly associated with each phenotype from published genome-wide association studies.

RESULTS

The genetic risk scores explained 6.31 and 1.46% of the variability in height and BMI, respectively. There was only weak evidence that genetic variants previously associated with increased BMI were associated with a lower prostate cancer risk (odds ratio per standard deviation increase in BMI genetic score 0.98; 95% CI 0.96, 1.00; p = 0.07). Genetic variants associated with increased height were not associated with prostate cancer incidence (OR 0.99; 95% CI 0.97, 1.01; p = 0.23), but were associated with an increase (OR 1.13; 95 % CI 1.08, 1.20) in prostate cancer mortality among low-grade disease (p heterogeneity, low vs. high grade <0.001). Genetic variants associated with increased BMI were associated with an increase (OR 1.08; 95 % CI 1.03, 1.14) in all-cause mortality among men with low-grade disease (p heterogeneity = 0.03).

CONCLUSIONS

We found little evidence of a substantial effect of genetically elevated height or BMI on prostate cancer risk, suggesting that previously reported observational associations may reflect common environmental determinants of height or BMI and prostate cancer risk. Genetically elevated height and BMI were associated with increased mortality (prostate cancer-specific and all-cause, respectively) in men with low-grade disease, a potentially informative but novel finding that requires replication.

Dairy intake after prostate cancer diagnosis in relation to disease-specific and total mortality

Information regarding postdiagnostic dairy intake and prostate cancer survival is limited. We evaluated intake of total, high-fat and low-fat dairy after prostate cancer diagnosis in relation to disease-specific and total mortality. We included 926 men from the Physicians' Health Study diagnosed with non-metastatic prostate cancer between 1982 and 2000 who completed a diet questionnaire a median of 5 years after diagnosis and were followed thereafter for a median of 10 years to assess mortality. Cox proportional hazards regression was used to estimate associations between dairy intake and prostate cancer specific and all-cause mortality. During 8,903 person-years of follow-up, 333 men died, 56 due to prostate cancer. Men consuming ≥3 servings/day of total dairy products had a 76% higher risk of total mortality and a 141% higher risk of prostate cancer-specific mortality compared to men who consumed less than 1 dairy product/day (hazard ratio (HR) = 1.76, 95% confidence interval (CI): 1.21, 2.55, ptrend  < 0.001 for total mortality; HR = 2.41, 95% CI: 0.96, 6.02, ptrend  = 0.04 for prostate cancer-specific mortality). The association between high-fat dairy and mortality risk appeared to be stronger than that of low-fat dairy, but the difference between them was not statistically significant (p for difference = 0.57 for prostate cancer-specific mortality and 0.56 for total mortality). Among men without metastases when diagnosed, higher intake of dairy foods after prostate cancer diagnosis may be associated with increased prostate cancer-specific and all-cause mortality.

Roles of caloric restriction, ketogenic diet and intermittent fasting during initiation, progression and metastasis of cancer in animal models: a systematic review and meta-analysis

BACKGROUND

The role of dietary restriction regimens such as caloric restriction, ketogenic diet and intermittent fasting in development of cancers has been detected via abundant preclinical experiments. However, the conclusions are controversial. We aim to review the relevant animal studies systematically and provide assistance for further clinical studies.

METHODS

Literatures on associations between dietary restriction and cancer published in PubMed in recent twenty years were comprehensively searched. Animal model, tumor type, feeding regimen, study length, sample size, major outcome, conclusion, quality assessment score and the interferential step of cancer were extracted from each eligible study. We analyzed the tumor incidence rates from 21 studies about caloric restriction.

RESULTS

Fifty-nine studies were involved in our system review. The involved studies explored roles of dietary restriction during initiation, progression and metastasis of cancer. About 90.9% of the relevant studies showed that caloric restriction plays an anti-cancer role, with the pooled OR (95%CI) of 0.20 (0.12, 0.34) relative to controls. Ketogenic diet was also positively associated with cancer, which was indicated by eight of the nine studies. However, 37.5% of the related studies obtained a negative conclusion that intermittent fasting was not significantly preventive against cancer.

CONCLUSIONS

Caloric restriction and ketogenic diet are effective against cancer in animal experiments while the role of intermittent fasting is doubtful and still needs exploration. More clinical experiments are needed and more suitable patterns for humans should be investigated.

Prediagnostic plasma IGFBP-1, IGF-1 and risk of prostate cancer

Insulin-like growth factor (IGF)-1 is associated with a higher risk of prostate cancer. IGF-binding protein (IGFBP)-1, a marker for insulin activity, also binds IGF-1 and inhibits its action. Data on IGFBP-1 and prostate cancer risk are sparse and whether the IGF and insulin axes interact to affect prostate cancer carcinogenesis is unknown. We evaluated the independent and joint influence of prediagnostic plasma levels of IGFBP-1 (fasting) and IGF-1 on risk of prostate cancer among 957 cases and 1,021 controls with fasting levels of IGFBP-1 and 1,709 cases and 1,778 controls with IGF-1 nested within the Health Professionals Follow-up Study. Unconditional logistic regression adjusting for matching factors was used to estimate the odds ratio (OR) and 95% confidence interval (CI). Higher prediagnostic fasting IGFBP-1 levels were associated with lower risk of prostate cancer (highest vs. lowest quartile OR = 0.67, 95% CI 0.52-0.86, p(trend) = 0.003), which remained similar after adjusting for IGF-1. Prediagnostic IGF-1 was associated with increased risk of prostate cancer (highest vs. lowest quartile OR = 1.28, 95% CI = 1.05-1.56, p(trend) = 0.01). The associations with each marker were primarily driven by lower-grade and non-advanced prostate cancer. Being low in IGFBP-1 and high in IGF-1 did not confer appreciable additional risk (p(interaction) = 0.42). In summary, prediagnostic fasting IGFBP-1 may influence prostate cancer carcinogenesis. Being low in IGFBP-1 or high in IGF-1 is sufficient to elevate the risk of prostate cancer.

[Metabolic syndrome and prostate cancer]

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

Molecular alterations and emerging targets in castration resistant prostate cancer

Prostate cancer is the most common malignancy in Western Europe, of which approximately 10-20% presents with advanced or metastatic disease. Initial response with androgen deprivation therapy is almost universal, but progression to castration resistant prostate cancer (CRPC), an incurable disease, occurs in approximately 2-3 years. In recent years, the novel taxane cabazitaxel, the hormonal agents abiraterone and enzalutamide, the immunotherapeutic agent sipuleucel-T and the radiopharmaceutical radium-223 have been shown to prolong survival in large randomised trials, thus widely increasing the therapeutic armamentarium against the disease. Despite these advances, the median survival in the first-line setting of metastatic castration-resistant prostate cancer (mCRPC) is still up to 25 months and in the post-docetaxel setting is about 15-18 months. There is an urgent need for the development of biomarkers of treatment response, and for a deeper understanding of tumour heterogeneity and the molecular biology underlying the disease. In this review, we attempt to provide insight into the novel molecular targets showing promise in clinical trials.

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.

GH therapy and cancer risk in hypopituitarism: what we know from human studies

It has been difficult to identify factors that affect the risk of cancer, but we know that people are at higher risk as they get older, or if they have a strong family history of cancer. The potential influence of environmental and behavioral factors remains poorly understood. Early population-based and case-control studies suggested that higher serum levels of IGF1 could be associated with increased cancer risk. Since GH therapy increases IGF1 levels, concern has been raised regarding its potential role as a cancer initiation factor. Experimental evidence and some clinical studies showed that when GH/IGF1 secretion or action was inhibited, a decreased incidence and rate of progression of cancers occurred. However, human populations comprise a garden variety of genotypes that respond differently to the same kind of exposures. Human population studies frequently reveal only very small effects to these exposures. So, are GH and cancer guilty by association? After more than 20 years, leukemia, a major safety issue initially believed associated with GH treatment in children with GH deficiency (GHD), has not been confirmed but the risk of second malignancies in patients previously treated with irradiation has been detected or confirmed through the National Cooperative Growth Study. Overall, this large study confirmed the favorable overall safety profile of GH therapy in children with GHD, and also highlighted specific populations at potential risk. The risk of secondary malignancy following radiotherapy is surely related to radiotherapy more than GH therapy that may increase growth but is less likely to start the oncogenic process. In GH-deficient adults treated with GH, observational studies (KIMS, HypoCCS) have shown that when IGF1 levels were targeted within normal age-related reference ranges, the occurrence of malignancies was not higher than in the general population.

Impact of targeting insulin-like growth factor signaling in head and neck cancers

The IGF system has been shown to have either negative or negligible impact on clinical outcomes of tumor development depending on specific tumor sites or stages. This review focuses on the clinical impact of IGF signaling in head and neck cancer, the effects of IGF targeted therapies, and the multi-dimensional role of IRS 1/2 signaling as a potential mechanism in resistance to targeted therapies. Similar to other tumor sites, both negative and positive correlations between levels of IGF-1/IGF-1-R and clinical outcomes in head and neck cancer have been reported. In addition, utilization of IGF targeted therapies has not demonstrated significant clinical benefit; therefore the prognostic impact of the IGF system on head and neck cancer remains uncertain.

A study of caloric restriction versus standard diet in overweight men with newly diagnosed prostate cancer: a randomized controlled trial

INTRODUCTION

Obese men have an increased risk of prostate cancer (PCa)-specific mortality. Potential mechanisms include insulin and related proteins. We investigate whether a short-term caloric restriction diet in overweight/obese men with newly diagnosed PCa can lead to measurable changes in patient anthropometrics and insulin-related proteins.

METHODS

Overweight and obese PCa patients choosing active surveillance or radical prostatectomy were randomized to a 6-week, caloric-restricted diet or to continue their current diet. Changes from baseline to end of study in anthropometrics, dietary constituents and serum proteins (insulin, c-peptide, IGF-1, adiponectin, IGF-BP3) were compared between the intervention and control groups using a Generalized Estimating Equation model.

RESULTS

Nineteen patients were randomized to the intervention (N = 10) or control (N = 9) group. Men in the intervention group had a 1.7% (3.7 lbs) mean decline in weight versus 1.0% (2.0 lbs) in controls (P < 0.05), and a reduced intake of calories, total and saturated fat, protein and starch (all P < 0.1 compared to controls). There was a significant difference (P = 0.002) in mean serum IGFBP-3 between the intervention (+2.8%) and control group (-6.9%). Other biomarkers changed with the diet intervention to a degree similar to previous weight loss studies but were not statistically significant compared with controls.

CONCLUSION

In this small pilot study, a 6-week caloric restricted diet in men with newly diagnosed PCa produced changes in weight, diet and serum proteins possibly related to prognosis. These results support larger-scale trials testing longer-term weight loss effects on potential PCa progression biomarkers.

Association of body mass index and prostate cancer mortality

OBJECTIVES

Inconsistent evidence exists on whether obesity is associated with an increased risk of prostate cancer death post-radical prostatectomy. We examined data from three large health plans to evaluate if an increased body mass index (BMI) at prostate cancer diagnosis is related to prostate cancer mortality

SUBJECTS AND METHODS

This population-based case-control study included 751 men with prostate cancer who underwent radical prostatectomy. Cases were men who died due to prostate cancer (N=323) and matched controls (N=428). We used multivariable logistic regression models to assess the association between BMI at diagnosis and prostate cancer mortality, adjusted for Gleason score, PSA, tumour characteristics, and matching factors.

RESULTS

Study subjects were classified into the following BMI (kg/m2) categories: healthy (18.5-24.9), overweight (25-29.9) and obese (≥30). Nearly 43% of the participants had a BMI ≥25 at diagnosis. A higher fraction of cases (30%) were obese compared to controls (22%). Overall, obese men had more than a 50% increase in prostate cancer mortality (adjusted odds ratio=1.50 [95% CI, 1.03-2.19]) when compared to men with healthy BMI. After stratifying by Gleason score, the odds of mortality generally rose with increasing BMI. The strongest effect was observed in the Gleason score 8+ category (2.37, 95% CI: 1.11-5.09). These associations persisted after adjusting for PSA at diagnosis and other tumour characteristics.

CONCLUSIONS

These results suggest that BMI at diagnosis is strongly correlated with prostate cancer mortality, and that men with aggressive disease have a markedly greater odds of death if they are overweight or obese.

Short hairpin ribonucleic acid constructs targeting insulin-like growth factor binding protein-3 ameliorates diabetes mellitus-related erectile dysfunction in rats

OBJECTIVE

To investigate the expression of insulin-like growth factor binding protein-3 (IGFBP-3) in penile cavernous of streptozotocin (STZ)-induced DM rats and whether downregulation of IGFBP-3 by intracavernosal injection of short hairpin ribonucleic acid (shRNA) targeting IGFBP-3 could improve the erectile function in DM rats.

MATERIALS AND METHODS

Diabetes was induced in rats by intraperitoneal injection of STZ, and the expression of IGFBP-3 in the penile tissue of adult normal and DM male rats was assayed using reverse transcriptase-polymerase chain reaction and Western blot. Next, shRNA-targeting IGFBP-3 and a scramble sequence were injected into the penile corpora cavernosa of DM rats. At 12 weeks after shRNA-IGFBP-3 administration, the intracavernous pressure in response to electrical stimulation of the cavernous nerves was evaluated. The expression of IGFBP-3 was assayed by Western blot. The concentration of cyclic guanosine monophosphate in the corpus cavernosum was assayed by enzyme-linked immunosorbent assay.

RESULTS

At 12 week after intraperitoneal administration of STZ, IGFBP-3 expression had increased in the penis of the DM rat (P <.05) compared with that of the normal control rats. Among the DM rats, IGFBP-3 expression at the messenger RNA and protein level was significantly inhibited 12 weeks after intracavernous administration of IGFBP-3 shRNA (P <.01). At 12 weeks after shRNA-IGFBP-3 injection, intracavernosal pressure was significantly increased in response to cavernous nerve stimulation (P <.05), and an increase in the concentration of cyclic guanosine monophosphate in the corpus cavernous tissue (P <.01) was detected compared with the "randomer" shRNA treatment group.

CONCLUSION

Gene transfer of shRNA-IGFBP-3 could improve erectile function in STZ-induced DM rats by an increase in the cyclic guanosine monophosphate concentration in cavernous tissue.

Insulin-like growth factor-1 genotypes and haplotypes influence the survival of prostate cancer patients with bone metastasis at initial diagnosis

Background

The insulin-like growth factor-1 (IGF-1) plays an important role in growth of prostate cancer (PCa) cells and facilitating the development and progression of PCa. This study aimed to evaluate the association of polymorphisms in three linkage disequilibrium (LD) blocks of the IGF-1 on the survival of metastatic PCa patients.

Methods

A total of 215 patients with bone metastases at initial presentation were included in this study. The cytosine-adenine (CA) repeat polymorphism and rs12423791 were selected as representative polymorphisms in the LD blocks 1 and 2, respectively. Haplotype in the LD block 3 was analyzed using two tag single nucleotide polymorphisms (SNPs), rs6220 and rs7136446. Cancer-specific survival rate was estimated from the Kaplan-Meier curve, and the survival data were compared using the log-rank test.

Results

Cancer-specific survival was significantly associated with the CA repeat polymorphism, rs12423791, and rs6220 (P = 0.013, 0.014, and 0.014, respectively). Although rs7136446 had no significant association with survival, the haplotype in the LD block 3 was significantly associated with cancer-specific survival (P = 0.0003). When the sum of the risk genetic factors in each LD block (19-repeat allele, C allele of rs12423791, or C-T haplotype) was considered, patients with all the risk factors had significantly shorter cancer specific-survival than those with 0–2 risk factors (P = 0.0003).

Conclusions

Polymorphisms in the IGF-1, especially a haplotype in the LD block 3, are assumed to be genetic markers predicting the outcome of metastatic PCa.

Effects of promoting longer-term and exclusive breastfeeding on adiposity and insulin-like growth factor-I at age 11.5 years: a randomized trial

IMPORTANCE

Evidence that longer-term and exclusive breastfeeding reduces child obesity risk is based on observational studies that are prone to confounding.

OBJECTIVE

To investigate effects of an intervention to promote increased duration and exclusivity of breastfeeding on child adiposity and circulating insulin-like growth factor (IGF)-I, which regulates growth.

DESIGN, SETTING, AND PARTICIPANTS

Cluster-randomized controlled trial in 31 Belarusian maternity hospitals and their affiliated clinics, randomized into 1 of 2 groups: breastfeeding promotion intervention (n = 16) or usual practices (n = 15). Participants were 17,046 breastfeeding mother-infant pairs enrolled in 1996 and 1997, of whom 13,879 (81.4%) were followed up between January 2008 and December 2010 at a median age of 11.5 years.

INTERVENTION

Breastfeeding promotion intervention modeled on the WHO/UNICEF Baby-Friendly Hospital Initiative (World Health Organization/United Nations Children's Fund).

MAIN OUTCOME MEASURES

Body mass index (BMI), fat and fat-free mass indices (FMI and FFMI), percent body fat, waist circumference, triceps and subscapular skinfold thicknesses, overweight and obesity, and whole-blood IGF-I. Primary analysis was based on modified intention-to-treat (without imputation), accounting for clustering within hospitals and clinics.

RESULTS

The experimental intervention substantially increased breastfeeding duration and exclusivity when compared with the control (43% vs 6% exclusively breastfed at 3 months and 7.9% vs 0.6% at 6 months). Cluster-adjusted mean differences in outcomes at 11.5 years of age between experimental vs control groups were: 0.19 (95% CI, -0.09 to 0.46) for BMI; 0.12 (-0.03 to 0.28) for FMI; 0.04 (-0.11 to 0.18) for FFMI; 0.47% (-0.11% to 1.05%) for percent body fat; 0.30 cm (-1.41 to 2.01) for waist circumference; -0.07 mm (-1.71 to 1.57) for triceps and -0.02 mm (-0.79 to 0.75) for subscapular skinfold thicknesses; and -0.02 standard deviations (-0.12 to 0.08) for IGF-I. The cluster-adjusted odds ratio for overweight/obesity (BMI ≥ 85th vs <85th percentile) was 1.18 (95% CI, 1.01 to 1.39) and for obesity (BMI ≥ 95th vs <85th percentile) was 1.17 (95% CI, 0.97 to 1.41).

CONCLUSIONS

AND RELEVANCE Among healthy term infants in Belarus, an intervention that succeeded in improving the duration and exclusivity of breastfeeding did not prevent overweight or obesity, nor did it affect IGF-I levels at age 11.5 years. Breastfeeding has many advantages but population strategies to increase the duration and exclusivity of breastfeeding are unlikely to curb the obesity epidemic.

TRIAL REGISTRATION

isrctn.org: ISRCTN37687716; and clinicaltrials.gov: NCT01561612.

Targeting IGF-IR with ganitumab inhibits tumorigenesis and increases durability of response to androgen-deprivation therapy in VCaP prostate cancer xenografts

Prostate cancer is the most commonly diagnosed malignancy in men. While tumors initially respond to androgen-deprivation therapy, the standard care for advanced or metastatic disease, tumors eventually recur as castration-resistant prostate cancer (CRPC). Upregulation of the insulin-like growth factor receptor type I (IGF-IR) signaling axis drives growth and progression of prostate cancer by promoting proliferation, survival, and angiogenesis. Ganitumab (formerly AMG 479) is a fully human antibody that inhibits binding of IGF-I and IGF-II to IGF-IR. We evaluated the therapeutic value of ganitumab in several preclinical settings including androgen-dependent prostate cancer, CRPC, and in combination with androgen-deprivation therapy. Ganitumab inhibited IGF-I-induced phosphorylation of the downstream effector AKT and reduced proliferation of multiple androgen-dependent and castration-resistant human prostate cancer cell lines in vitro. Ganitumab inhibited androgen-dependent VCaP xenograft growth and increased tumor-doubling time from 2.3 ± 0.4 weeks to 6.4 ± 0.4 weeks. Ganitumab blocked growth of castration-resistant VCaP xenografts for over 11.5 weeks of treatment. In contrast, ganitumab did not have appreciable effects on the castration-resistant CWR-22Rv1 xenograft model. Ganitumab was most potent against VCaP xenografts when combined with complete androgen-deprivation therapy (castration). Tumor volume was reduced by 72% after 4 weeks of treatment and growth suppression was maintained over 16 weeks of treatment. These data suggest that judicious use of ganitumab particularly in conjunction with androgen-deprivation therapy may be beneficial in the treatment of prostate cancer.

Evidence for the Possible Biological Significance of the igf-1 Gene Alternative Splicing in Prostate Cancer

Insulin-like growth factor-I (IGF-I) has been implicated in the pathogenesis of prostate cancer (PCa), since it plays a key role in cell proliferation, differentiation, and apoptosis. The IGF-I actions are mediated mainly via its binding to the type I IGF receptor (IGF-IR), however IGF-I signaling via insulin receptor (IR) and hybrid IGF-I/IR is also evident. Different IGF-I mRNA splice variants, namely IGF-IEa, IGF-IEb, and IGF-IEc, are expressed in human cells and tissues. These transcripts encode several IGF-I precursor proteins which contain the same bioactive product (mature IGF-I), however, they differ by the length of their signal peptides on the amino-terminal end and the structure of the extension peptides (E-peptides) on the carboxy-terminal end. There is an increasing interest in the possible different role of the IGF-I transcripts and their respective non-(mature)IGF-I products in the regulation of distinct biological activities. Moreover, there is strong evidence of a differential expression profile of the IGF-I splice variants in normal versus PCa tissues and PCa cells, implying that the expression pattern of the various IGF-I transcripts and their respective protein products may possess different functions in cancer biology. Herein, the evidence that the IGF-IEc transcript regulates PCa growth via Ec peptide specific and IGF-IR/IR-independent signaling is discussed.

Obesity and prostate cancer: weighing the evidence

CONTEXT

Obesity and prostate cancer (PCa) affect substantial proportions of Western society. Mounting evidence, both epidemiologic and mechanistic, for an association between the two is of public health interest. An improved understanding of the role of this modifiable risk factor in PCa etiology is imperative to optimize screening, treatment, and prevention.

OBJECTIVE

To consolidate and evaluate the evidence for an epidemiologic link between obesity and PCa, in addition to examining the proposed underlying molecular mechanisms.

EVIDENCE ACQUISITION

A PubMed search for relevant articles published between 1991 and July 2012 was performed by combining the following terms: obesity, BMI, body mass index and prostate cancer risk, prostate cancer incidence, prostate cancer mortality, radical prostatectomy, androgen-deprivation therapy, external-beam radiation, brachytherapy, prostate cancer and quality of life, prostate cancer and active surveillance, in addition to obesity, BMI, body mass index and prostate cancer and insulin, insulin-like growth factor, androgen, estradiol, leptin, adiponectin, and IL-6. Articles were selected based on content, date of publication, and relevancy, and their references were also searched for relevant articles.

EVIDENCE SYNTHESIS

Increasing evidence suggests obesity is associated with elevated incidence of aggressive PCa, increased risk of biochemical failure following radical prostatectomy and external-beam radiotherapy, higher frequency of complications following androgen-deprivation therapy, and increased PCa-specific mortality, although perhaps a lower overall PCa incidence. These results may in part relate to difficulties in detecting and treating obese men. However, multiple molecular mechanisms could explain these associations as well. Weight loss slows PCa in animal models but has yet to be fully tested in human trials.

CONCLUSIONS

Obesity appears to be linked with aggressive PCa. We suggest clinical tips to better diagnose and treat obese men with PCa. Whether reversing obesity slows PCa growth is currently unknown, although it is an active area of research.

Insulin-like growth factors (IGFs) and IGF-binding proteins in active monitoring of localized prostate cancer: a population-based observational study

PURPOSE

Active monitoring of prostate cancer requires the selection of low-risk cancers and subsequent identification of disease progression. Our objective was to determine whether serum insulin-like growth factor (IGF)-I, IGF-II, IGF-binding protein (IGFBP)-2 or IGFBP-3 at diagnosis (potential biomarkers of prognosis), and repeated measures of IGFBP-2 (potential biomarker of tumour growth), were associated with annual change in PSA and PSA doubling time (PSADT), proxies for disease progression.

METHODS

We investigated associations of circulating IGFs and IGFBPs with PSA measures using multilevel models, in 909 men (recruited between 1999 and 2009) with PSA-detected clinically localized prostate cancer undergoing active monitoring in the United Kingdom. Each man had an average of 14 measurements of PSA during a mean of 4-year follow-up.

RESULTS

IGF-I, IGF-II, IGFBP-2, and IGFBP-3 were not associated with baseline PSA. There was weak evidence that IGF-I at diagnosis was positively associated with a rapid post-diagnosis PSADT (≤4 years vs. >4 years): OR 1.34 (95 % CI 0.98, 1.81) per SD increase in IGF-I. IGFBP-2 increased by 2.1 % (95 % CI 1.4, 2.8) per year between 50 and 70 years, with no association between serial IGFBP-2 levels and PSADT. There was no evidence that serum IGF-II, IGFBP-2, or IGFBP-3, or post-diagnosis IGFBP-2, were associated with PSA kinetics in men with PSA-detected localized prostate cancer.

CONCLUSIONS

The weak association of IGF-I with PSADT requires replication in larger datasets, and more definitive evidence will be provided on the maturity of long-term active monitoring cohorts with relevant clinical outcomes (metastasis and prostate cancer mortality).

Insulin-like growth factor-I concentration and risk of prostate cancer: results from the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

High circulating insulin-like growth factor-I (IGF-I) concentrations have been associated with increased risk for prostate cancer in several prospective epidemiological studies. In this study, we investigate the association between circulating IGF-I concentration and risk of prostate cancer over the long term in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

METHODS

In a nested case-control design, 1,542 incident prostate cancer cases from eight European countries were individually matched to 1,542 controls by study center, age at recruitment, duration of follow-up, time of day, and duration of fasting at blood collection. Conditional logistic regression models were used to calculate risk for prostate cancer associated with IGF-I concentration, overall and by various subgroups.

RESULTS

Circulating IGF-I concentration was associated with a significant increased risk for prostate cancer [OR for highest vs. lowest quartile, 1.69; 95% confidence interval (CI), 1.35-2.13; P(trend) = 0.0002]. This positive association did not differ according to duration of follow-up [ORs for highest vs. lowest quartile were 2.01 (1.35-2.99), 1.37 (0.94-2.00), and 1.80 (1.17-2.77) for cancers diagnosed <4, 4-7, and >7 years after blood collection, respectively (P(heterogeneity) = 0.77)] or by stage, grade, and age at diagnosis or age at blood collection (all subgroups P(heterogeneity) >0.05).

CONCLUSION

In this European population, high circulating IGF-I concentration is positively associated with risk for prostate cancer over the short and long term.

IMPACT

As IGF-I is the only potentially modifiable risk factor so far identified, research into the effects of reducing circulating IGF-I levels on subsequent prostate cancer risk is warranted.