Lifestyle factors and insulin-like growth factor 1 levels among elderly men:

Protein intake and cancer: an umbrella review of systematic reviews for the evidence-based guideline of the German Nutrition Society

PURPOSE

It has been proposed that a higher habitual protein intake may increase cancer risk, possibly via upregulated insulin-like growth factor signalling. Since a systematic evaluation of human studies on protein intake and cancer risk based on a standardised assessment of systematic reviews (SRs) is lacking, we carried out an umbrella review of SRs on protein intake in relation to risks of different types of cancer.

METHODS

Following a pre-specified protocol (PROSPERO: CRD42018082395), we retrieved SRs on protein intake and cancer risk published before January 22th 2024, and assessed the methodological quality and outcome-specific certainty of the evidence using a modified version of AMSTAR 2 and NutriGrade, respectively. The overall certainty of evidence was rated according to predefined criteria.

RESULTS

Ten SRs were identified, of which eight included meta-analyses. Higher total protein intake was not associated with risks of breast, prostate, colorectal, ovarian, or pancreatic cancer incidence. The methodological quality of the included SRs ranged from critically low (kidney cancer), low (pancreatic, ovarian and prostate cancer) and moderate (breast and prostate cancer) to high (colorectal cancer). The outcome-specific certainty of the evidence underlying the reported findings on protein intake and cancer risk ranged from very low (pancreatic, ovarian and prostate cancer) to low (colorectal, ovarian, prostate, and breast cancer). Animal and plant protein intakes were not associated with cancer risks either at a low (breast and prostate cancer) or very low (pancreatic and prostate cancer) outcome-specific certainty of the evidence. Overall, the evidence for the lack of an association between protein intake and (i) colorectal cancer risk and (ii) breast cancer risk was rated as possible. By contrast, the evidence underlying the other reported results was rated as insufficient.

CONCLUSION

The present findings suggest that higher total protein intake may not be associated with the risk of colorectal and breast cancer, while conclusions on protein intake in relation to risks of other types of cancer are restricted due to insufficient evidence.

The effects of lycopene supplementation on serum insulin-like growth factor 1 (IGF-1) levels and cardiovascular disease: A dose-response meta-analysis of clinical trials

BACKGROUND

The results of human studies assessing the efficacy of lycopene on insulin-like growth factor 1 (IGF-1) levels are inconsistent. Thus, we performed a systematic review and meta-analysis to examine the effects of lycopene supplementation on serum IGF-1 levels and cardiovascular disease.

METHODS

The literature published up to January 2020 was searched using the electronic databases Scopus, PubMed/Medline, Web of Science, Embase and Google Scholar.

RESULTS

Seven qualified trials were included in the current meta-analysis. IGF-1 levels were non-significantly decreased in lycopene group compared to the control (WMD: -6.74 ng/mL, 95 % CI: -23.01 to 9.52, p = 0.42; I² = 94.3 %). Subgroup analysis revealed a significantly decrease in IGF-1 levels upon lycopene supplementation at doses ≥15 mg/d (WMD: -6.40 ng/mL), intervention period <12 weeks (WMD: -6.49 ng/mL), and subjects aged ≥60 years (WMD: -24.98 mg/dl). In addition, lycopene intake significantly reduced IGF-1 levels upon healthy conditions (WMD: -25.59 ng/mL) when compared with cancer patients (WMD: 0.35 ng/mL). In addition, the effect of lycopene supplementation was significant in patients diagnosed with cardiac disorders.

CONCLUSION

Overall, lycopene intake was not associated with reduced serum IGF-1 levels. However, association was significant when lycopene was administrated at doses >15 mg/d, for <12 weeks, as well as for healthy conditions and patients aged ≥60 years. In addition, lycopene supplementation exhibited potential health benefits in the management of patients with cardiac disorders.

Diet and Lifestyle in Prostate Cancer

A variety of diet and lifestyle factors have been studied with respect to prostate cancer risk in large, prospective cohort studies. In spite of this work, and in contrast to other common cancers, few modifiable risk factors have been firmly established as playing a role in prostate cancer. There are several possible explanations for the lack of well-established risk factors. First, prostate cancer has among the highest heritability of all common cancers; second, early life exposures may play an important role in risk, rather than mid- and later-life exposures assessed in most epidemiological studies. Finally, prostate-specific antigen (PSA) screening plays a critical role in prostate cancer detection and incidence rates, which has important implications for epidemiological studies.Among modifiable risk factors, smoking and obesity are consistently associated with higher risk specifically of advanced prostate cancer. There is also considerable evidence for a positive association between dairy intake and overall prostate cancer risk, and an inverse association between cooked tomato/lycopene intake and risk of advanced disease. Several other dietary factors consistently associated with risk in observational studies, including selenium and vitamin E, have been cast into doubt by results from clinical trials. Results for other well-studied dietary factors, including fat intake, red meat, fish, vitamin D, soy and phytoestrogens are mixed.In practical terms, men concerned with prostate cancer risk should be encouraged to stop smoking, be as physically active as possible, and achieve or maintain a healthy weight. These recommendations also have the advantage of having a positive impact on risk of type 2 diabetes, cardiovascular disease, and other chronic diseases. Reducing dairy intake while increasing consumption of fish and tomato products is also reasonable advice.

Association of dietary intake of milk and dairy products with blood concentrations of insulin-like growth factor 1 (IGF-1) in Bavarian adults

PURPOSE

Circulating IGF-1 concentrations have been associated with higher cancer risk, particularly prostate, breast and colorectal cancer. There is evidence from observational and intervention studies that milk and dairy products intake is associated with higher IGF-1 concentrations, but results were not always consistent. The purpose of this study was to examine the relationship between dairy intake and circulating IGF-1 concentrations in participants of the Second Bavarian Food Consumption Survey, thereby providing data for a German population for the first time.

METHODS

In this cross-sectional study of 526 men and women aged 18-80 years, in contrast to most previous investigations, dietary intake was assessed with a more detailed instrument than food frequency questionnaires (FFQs), i.e., by three 24-h dietary recalls conducted on random days close in time to the blood collection. Circulating IGF-1 concentrations were measured in blood samples. Multivariable linear regression models were used to examine the association of dairy intake with IGF-1 concentrations.

RESULTS

Each 400 g increment in daily dairy intake was associated with 16.8 µg/L (95% CI 6.9, 26.7) higher IGF-1 concentrations. Each 200 g increment in milk per day was associated with 10.0 µg/L (95% CI 4.2, 15.8) higher IGF-1. In contrast, we observed no association between cheese or yogurt intake and IGF-1 concentrations.

CONCLUSIONS

Our findings are in line with most previous investigations and support the hypothesis that dairy and milk intake are associated with higher IGF-1 concentrations.

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 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.

Insulin-like growth factor pathway genes and blood concentrations, dietary protein and risk of prostate cancer in the NCI Breast and Prostate Cancer Cohort Consortium (BPC3)

It has been hypothesized that a high intake of dairy protein may increase prostate cancer risk by increasing the production of insulin-like growth factor 1 (IGF-1). Several single nucleotide polymorphisms (SNPs) have been weakly associated with circulating concentrations of IGF-1 and IGF binding protein 3 (IGFBP-3), but none of these SNPs was associated with risk of prostate cancer. We examined whether an association between 16 SNPs associated with circulating IGF-1 or IGFBP-3 concentrations and prostate cancer exists within subgroups defined by dietary protein intake in 5,253 cases and 4,963 controls of European ancestry within the NCI Breast and Prostate Cancer Cohort Consortium (BPC3). The BPC3 includes nested case-control studies within large North-American and European cohorts. Per-allele odds ratios for prostate cancer for the SNPs were compared across tertiles of protein intake, which was expressed as the percentage of energy derived from total, animal, dairy or plant protein sources, using conditional logistic regression models. Total, animal, dairy and plant protein intakes were significantly positively associated with blood IGF-1 (p < 0.01), but not with IGFBP-3 concentrations (p > 0.10) or with risk of prostate cancer (p > 0.20). After adjusting for multiple testing, the SNP-prostate cancer associations did not differ by intakes of protein, although two interactions by intake of plant protein were of marginal statistical significance [SSTR5 (somatostatin receptor 5)-rs197056 (uncorrected p for interaction, 0.001); SSTR5-rs197057 (uncorrected p for interaction, 0.002)]. We found no strong evidence that the associations between 16 IGF pathway SNPs and prostate cancer differed by intakes of dietary protein.

The role of lycopene and its derivatives in the regulation of transcription systems: implications for cancer prevention

Evidence from epidemiologic studies has suggested that carotenoids, and lycopene in particular, decrease the risk of cancer: however, not all studies support this view. To gain insight into the molecular mechanisms whereby lycopene and other carotenoids may exert their chemoprotective effects, we and others performed a series of studies that used a large panel of cancer cell lines of different lineages and animal models of human cancer. In this review we address some of the mechanisms proposed for the cancer-preventive activity of tomato lycopene, focusing on the induction of the antioxidant response element transcription system and the inhibition of the transcriptional activity of sex hormones, such as estrogens and androgens, and the activity of growth factors, such as insulin-like growth factor. We also considered the modulation by lycopene of the transcription factors peroxisome proliferator-activated receptor, retinoid X receptor, liver X receptor, and activating protein-1. The ligands and the phytonutrient regulators of these transcription systems contain electrophilic active groups, whereas lycopene and nonxanthophylic carotenoids are devoid of them. Thus, we suggest that at least some of the cellular effects of carotenoids are mediated through their derivatives formed either by chemical oxidation or by enzymatic cleavage inside the cells. This review highlights findings that pertain to this exciting avenue of research, which is currently under intense scrutiny in several laboratories worldwide.

The association between height and prostate cancer grade in the Early Stage Prostate Cancer Cohort Study

OBJECTIVE

We examined the relationship between height and prostate cancer grade.

METHODS

The Early Stage Prostate Cancer Cohort Study is an observational cohort of 1,037 men diagnosed with early-stage prostate cancer, T(0-3)N(x)M(0). High-grade prostate cancer was defined as a biopsy Gleason score ≥ 7 (4 + 3). Logistic regression models were created to calculate odds ratios (OR) and 95% confidence intervals (CI) for the cross-sectional relationship between height and prostate cancer grade in the overall cohort and subpopulations.

RESULTS

We identified 939 participants with a biopsy Gleason score. High-grade prostate cancer was diagnosed in 138 participants. Overall, participants in the highest quartile of height were more than twice as likely to have a Gleason score ≥ 7 (4 + 3) than participants in the lowest quartile of height, OR 2.14 (95% CI 1.11, 4.14), after multivariate adjustment. Participants in the highest quartile of height were more likely to be diagnosed with high-grade prostate cancer than participants in the lowest quartile of height among participants who were black, OR 8.00 (95% CI 1.99, 32.18), and participants who had diabetes mellitus, OR 5.09 (95% CI 1.30, 19.98).

CONCLUSIONS

Height is associated with increased risk of high-grade prostate cancer overall and perhaps among certain subpopulations.

Effects of high-isoflavone soy diet vs. casein protein diet and obesity on DMBA-induced mammary tumor development

Obesity and elevated serum insulin growth factor-1 (IGF-1) level are major risk factors in the development of breast cancer. We investigated the long-term effects of high-isoflavone soy intake and obesity on 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumor development and on serum IGF-1 and binding protein (IGFBP-3) levels. Lean and obese female Zucker rats fed casein or high-isoflavone soy protein were orally gavaged at age 50 days with DMBA and sacrificed after 147 days. The majority of lean casein-fed rats (69%) developed mammary tumors compared to 50% in lean soy-fed rats (P=0.176). In the obese groups, 76% of soy-fed rats developed mammary tumors compared to 15% of obese casein-fed rats (P<0.001). At age 43 days, IGFBP-3 was increased in the lean soy-fed rats compared to the lean casein-fed rats (P<0.05). At age 99 days, soy- and obese casein-fed rats exhibited increased serum IGF-1 compared to the lean rats and this increase was maintained for the rest of the experiment (P<0.05). Obese rats fed casein exhibited increased IGFBP-3 levels (P<0.001). However, obese rats fed soy exhibited a significant decrease in IGFBP-3 levels compared to the lean soy-fed rats (P<0.001) and a significant decrease in IGFBP-3 levels compared to the obese casein-fed rats (P<0.001). At age 197 days, IGFBP-3 levels were increased in obese casein-and soy-fed rats (P<0.001). The results suggest that female Zucker rats fed casein diets are protected against DMBA-induced mammary tumors, which is not the case for those on high-isoflavone soy diet, and changes in the concentration of serum IGFBP-3 may contribute to the incidence of DMBA-induced mammary tumors.

Relationship between growth hormone 1 genetic polymorphism and susceptibility to colorectal cancer

The aim of this study was to evaluate the relationship between smoking, alcohol drinking and genetic polymorphism of the growth hormone 1 gene (GH1) T1663A with reference to colorectal cancer. We conducted a case-control study with 315 cases of colorectal cancer and 438 population-based controls in the Jiangsu Province, China. GH1 T1663A genotypes were identified using PCR-RFLP (restriction fragment length polymorphism) methods. Information on smoking and drinking was collected using a questionnaire. Odds ratios (ORs) were estimated with an unconditional logistic model. The distribution of T/T and A/A genotypes was significantly different between controls and cases (chi(2)(MH)=3.877, P=0.049). Compared with the GH1 T/T genotype, the A/A genotype was at a decreased risk of developing colorectal cancer (sex-, age-, body mass index-, smoking- and alcohol drinking-adjusted OR=0.56, 95% confidence interval: 0.34-0.90). Smoking was not associated with the risk of colorectal cancer, whereas alcohol drinking was associated with an increased risk of colorectal cancer. Among nonsmokers or nondrinkers, individuals who had the GH1 A/A genotype were at a decreased risk of developing colorectal cancer compared with individuals who had the GH1 T allele. These results show that the GH1 T1663A A/A genotype can decrease the risk for colorectal cancer.

Alcohol use and prostate cancer: a meta-analysis

Past reviews have concluded that there is no association between alcohol use and prostate cancer incidence. We performed a meta-analysis of existing epidemiological studies finding, in contrast, evidence to suggest that prostate incidence is positively linearly associated with heavier alcohol use. This finding was largely due to the contribution of population case-control studies and those measuring men recruited before age 60. No relationship between alcohol consumption and prostate cancer was found for cohort and hospital case-control studies. Analyses of design effects modestly suggests that population case-control studies were probably better suited to identify potential alcohol-prostate cancer relationships due to the close temporal proximity of the measurement of level of alcohol consumption to diagnosis. Future efforts should be made to exclude all ill subjects from control groups/baseline samples in addition to accounting for changes in consumption with advancing age and the onset of illness. The alcohol-prostate cancer association remained significant despite controlling for the degree to which studies endeavored to eliminate false negatives from their control groups.

Insulin-like growth factor-I, insulin-like growth factor binding protein-3 and risk of benign prostate hyperplasia in the prostate cancer prevention trial

BACKGROUND

We investigated whether peptides involved in cellular proliferation and apoptosis, [insulin-like growth factor I (IGFI) and its major binding protein (insulin-like growth factor binding protein 3)], predicted risk of benign prostate hyperplasia (BPH).

METHODS

We conducted a nested-case-control study in the placebo arm of the prostate cancer prevention trial (PCPT). Cases (n = 727) were men with surgical or medical treatment for BPH; two or more IPSS scores >14; or two scores of at least five points over baseline one of which was >or=12. Controls (n = 727) were frequency matched by age to cases, reported no BPH treatment, and no IPSS score >8. Cases and controls remained on the PCPT placebo and were followed closely until their 7-year PCPT anniversary. Baseline serum was analyzed for IGFI and IGFBP3. Unconditional logistic regression and polytomous regression estimated the multivariate-adjusted odds ratio (OR) for BPH risk.

RESULTS

IGFBP3 was inversely and the IGFI:IGFBP3 ratio was positively associated with BPH risk, but findings were statistically significant only for men with severe symptoms (OR = 0.60, 95% CI = 0.40-0.90 for the fifth vs. first quintile of IGFBP3, P-trend = 0.01). Associations did not differ by age (<65 or >or=65 years), and there was a suggestion that the IGFI:IGFBP3 - BPH risk association may be stronger among overweight men.

CONCLUSIONS

A high IGFI:IGFBP3 ratio was associated with increased BPH risk, and high serum IGFBP3 was associated with decreased BPH risk among men with severe symptoms. These results confirm findings from other recent studies.

Lycopene supplementation elevates circulating insulin-like growth factor binding protein-1 and -2 concentrations in persons at greater risk of colorectal cancer

BACKGROUND

Higher circulating insulin-like growth factor I (IGF-I) concentrations have been related to a greater risk of cancer. Lycopene intake is inversely associated with cancer risk, and experimental studies have shown that it may affect the IGF system, possibly through an effect on IGF-binding proteins (IGFBPs).

OBJECTIVE

The objective of our study was to investigate the effect of an 8-wk supplementation with tomato-derived lycopene (30 mg/d) on serum concentrations of total IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3.

DESIGN

We conducted a randomized, placebo-controlled, double-blinded crossover study in 40 men and 31 postmenopausal women with a family history of colorectal cancer, a personal history of colorectal adenoma, or both.

RESULTS

Lycopene supplementation significantly (P = 0.01) increased serum IGFBP-1 concentrations in women (median relative difference between serum IGFBP-1 concentrations after lycopene supplementation and after placebo, 21.7%). Serum IGFBP-2 concentrations were higher in both men and women after lycopene supplementation than after placebo, but to a lesser extent (mean relative difference 8.2%; 95% CI: 0.7%, 15.6% in men and 7.8%; 95% CI: -5.0%, 20.6% in women). Total IGF-I, IGF-II, and IGFBP-3 concentrations were not significantly altered by lycopene supplementation.

CONCLUSIONS

This is the first study known to show that lycopene supplementation may increase circulating IGFBP-1 and IGFBP-2 concentrations. Because of high interindividual variations in IGFBP-1 and IGFBP-2 effects, these results should be confirmed in larger randomized intervention studies.

Tomato lycopene extract supplementation decreases insulin-like growth factor-I levels in colon cancer patients

Epidemiological studies have shown that high serum levels of insulin-like growth factor-I are associated with an increased risk of colon and other types of cancer. The aim of this study was to determine whether short intervention with dietary tomato lycopene extract will affect serum levels of the insulin-like growth factor system components in colon cancer patients. The study had a double-blind, randomized, placebo-controlled design. Colon cancer patients (n=56), candidates for colectomy, were recruited from the local community a few days to a few weeks before surgery. Personal and medical data were recorded. Plasma concentrations of insulin-like growth factor-I and II and insulin-like growth factor-I-binding protein-3 were assayed by routine laboratory methods. Lycopene was assayed by high-performance liquid chromatography. Plasma lycopene levels increased by twofold after supplementation with tomato lycopene extract. In the placebo-treated group, there was a small nonsignificant increase in lycopene plasma levels. The plasma concentration of insulin-like growth factor-I decreased significantly by about 25% after tomato lycopene extract supplementation as compared with the placebo-treated group (P<0.05). No significant change was observed in insulin-like growth factor-I-binding protein-3 or insulin-like growth factor-II, whereas the insulin-like growth factor-I/insulin-like growth factor-I-binding protein-3 molar ratio decreased significantly (P<0.05). Given that high plasma levels of insulin-like growth factor-I have been suggested as a risk factor for various types of cancer including colon cancer, the results support our suggestion that tomato lycopene extract has a role in the prevention of colon and possibly other types of cancer.

Milk as a food for growth? The insulin-like growth factors link

Objective

The mechanisms underlying the association of insulin-like growth factor-I (IGF-I) and leg length (a marker of prepubertal growth) with cancer risk are uncertain. One hypothesis is that diet in early childhood might provide the link. The aim of the present study was to examine the association between early diet – in particular, the intakes of cows' milk and dairy products – and height, leg length and IGF-I levels at age 7–8 years.

Subjects

Children participating in the Avon Longitudinal Study of Parents and Children.

Design

Diet was assessed using a 3-day unweighed food record. Anthropometry, IGF-I and insulin-like growth factor-binding protein-3 (IGFBP-3) were measured by standard methods.

Results

Data on both diet and height were available for 744 children (404 boys) and on diet and IGF for 538 (295 boys). After adjusting for energy, both cows' milk and dairy product intakes were positively associated with IGF-I (P=0.040 and 0.027, respectively) and IGFBP-3 levels (P=0.082 and 0.067, respectively). These associations persisted on adjustment for potential confounders, but were abolished on controlling for protein intake. In energy-adjusted models there was only weak evidence of associations of milk and dairy product intakes with anthropometry. In boys only, dairy product intake was positively associated with leg length (equivalent to a 0.058 (0.002, 0.114) standard deviation score increase in leg length per 100 g increase in daily intake).

Conclusions

These data provide some evidence that variation in childhood milk and dairy product intakes underlies associations of leg length, IGF-I and cancer risk. The association appears to be due to the protein content of milk.

Molecular markers in the diagnosis of prostate cancer

The genetic alterations leading to prostate cancer are gradually being discovered. A wide variety of genes have been associated with prostate cancer development as well as tumor progression. Knowledge of gene polymorphisms associated with disease aid in the understanding of important pathways involved in this process and may result in the near future in clinical applications. Urinary molecular markers will soon be available to aid in the decision of repeat prostate biopsies. Recent findings suggest the importance of androgen signaling in disease development and progression. The further understanding of interaction of inflammation, diet, and genetic predisposition will improve risk stratification in the near future.

Insulin-like growth factor-I and growth in height, leg length, and trunk length between ages 5 and 10 years

OBJECTIVE

IGF-I, a major regulator of childhood growth, is also associated with the risk of several cancers in adult life. Adult height and particularly leg length are also associated with cancer risk. Prepubertal growth is more in leg than trunk length, and it has been suggested that leg length might be a biomarker of childhood IGF-I. However, there is little information on the association between childhood IGF-I and subsequent leg and trunk growth. In this study, we investigated the association of IGF-I measured at 5 and 7-8 yr with growth in height and the components of height (leg and trunk length) from 5 yr to 9-10 yr.

PARTICIPANTS

A total of 675 children participated in the Avon Longitudinal Study of Parents and Children.

RESULTS

IGF-I was strongly positively associated with growth in height in both sexes. Among boys, IGF-I was strongly associated with subsequent growth in both leg and trunk length, but there was no evidence that IGF-I was more strongly associated with one component of growth than the other. Among girls, IGF-I was strongly positively associated with growth in trunk but not leg length, although there was only weak evidence that these two associations differed in strength (P = 0.058).

CONCLUSIONS

These results support the contention that the associations between height and cancer may be mediated by variation in childhood IGF-I. However, they provide no evidence to support the hypothesis that leg length is a better biomarker of childhood IGF-I levels than trunk length.

Modulation of the growth hormone-insulin-like growth factor (GH-IGF) axis by pharmaceutical, nutraceutical and environmental xenobiotics: an emerging role for xenobiotic-metabolizing enzymes and the transcription factors regulating their expression. A review

The growth hormone-insulin-like growth factor (GH-IGF) axis has gained considerable focus over recent years. One cause of this increased interest is due to a correlation of age-related decline in plasma GH/IGF levels with age-related degenerative processes, and it has led to the prescribing of GH replacement therapy by some practitioners. On the other hand, however, research has also focused on the pro-carcinogenic effects of high GH-IGF levels, providing strong impetus for finding regimes that reduce its activity. Whereas the effects of GH/IGF activity on the action of xenobiotic-metabolizing enzyme systems is reasonably well appreciated, the effects of xenobiotic exposure on the GH-IGF axis has not received substantial review. Relevant xenobiotics are derived from pharmaceutical, nutraceutical and environmental exposure, and many of the mechanisms involved are highly complex in nature, not easily predictable from existing in vitro tests and do not always predict well from in vivo animal models. After a review of the human and animal in vivo and in vitro literature, a framework for considering the different levels of direct and indirect modulation by xenobiotics is developed herein, and areas that still require further investigation are highlighted, i.e. the actions of common endocrine disruptors such as pesticides and phytoestrogens, as well as the role of xenobiotic-metabolizing enzymes and the transcription factors regulating their expression. It is anticipated that a fuller appreciation of the existing human paradigms for GH-IGF axis modulation gained through this review may help explain some of the variation in levels of plasma IGF-1 and its binding proteins in the population, aid in the prescription of particular dietary regimens to certain individuals such as those with particular medical conditions, guide the direction of long-term drug/nutraceutical safety trials, and stimulate ideas for future research. It also serves to warn athletes that using compounds touted as performance enhancing because they promote short-term GH release could in fact be detrimental to performance in the long-run.

Associations of childhood and adulthood height and the components of height with insulin-like growth factor levels in adulthood: a 65-year follow-up of the Boyd Orr cohort

CONTEXT

Taller individuals with longer legs have a higher risk of cancer but a lower risk of coronary heart disease.

OBJECTIVE

We investigated whether childhood height and its components are associated with the IGF system in adulthood.

DESIGN AND PARTICIPANTS

We analyzed data from 429 participants of the Boyd Orr cohort, for whom height measured in childhood (mean age, 7.4 yr) in 1937-1939 could be related to levels of IGF-I, IGF-II, IGF binding protein (IGFBP)-2, and IGFBP-3 in adulthood (mean age, 71.1 yr). In 385 participants, measured height in adulthood could be related to IGF levels.

RESULTS

In fully adjusted models (controlling for age, sex, socioeconomic factors, lifestyle, and body mass index), childhood height and its components were not associated with adult circulating IGF-I, IGF-II, or IGFBP-2 levels. IGFBP-3 was 85.5 ng/ml higher (95% confidence interval, -11.6 to 182.5; P = 0.08) per sd increase in childhood trunk length and 83.6 ng/ml lower (95% confidence interval, -10.3 to 177.5; P = 0.08) per sd increase in childhood leg/trunk ratio. Height in adulthood was not associated with IGF-I, IGF-II, or IGFBP-3 and was inversely associated with IGFBP-2 (P = 0.05) after additionally controlling for childhood height.

CONCLUSION

There was no evidence that associations of childhood height with cancer and coronary heart disease risk are mediated by IGF-I in adulthood. The anthropometric associations with IGFBP-2 and IGFBP-3 could be chance findings but warrant additional investigation. IGF levels in childhood may be more important determinants of long-term disease risk than adult levels.

Variation in plasma insulin-like growth factor-1 and insulin-like growth factor binding protein-3: personal and lifestyle factors (United States)

Insulin-like growth factors (IGFs) play an important role in cell proliferation and apoptosis, and recent epidemiologic studies have suggested that circulating IGF-1 and IGF binding protein-3 (IGFBP-3) may be related to colorectal, breast, and prostate cancer risk. The purpose of this analysis was to investigate the role of various personal and lifestyle factors in the inter-individual variation of circulating IGF-1 and IGFPB-3. We measured plasma levels of IGF-1 and IGFBP-3 in a sequential sample of 333 population-based control subjects enrolled in the Seattle Colorectal Cancer Family Registry from August 1999 through December 2001, who had provided a blood sample. Total IGF-1 and IGFBP-3 were measured from plasma samples using ELISA assays. Interviewer-administered questionnaires collected data on various personal and lifestyle factors. Multivariate-adjusted linear regression was used to assess the associations between specific personal and lifestyle factors with IGF-1 and IGFBP-3 levels. Age, body mass index, and postmenopausal hormone use were statistically significantly inversely related to IGF-1 concentrations, and milk consumption was significantly positively related to IGF-1 levels. Only age was significantly related to circulating IGFBP-3. Although the sources of inter-individual variation of IGF-1 and IGFB-3 are not yet fully understood, this analysis provides some insights into factors that may contribute.

Racial and anthropometric differences in plasma levels of insulin-like growth factor I and insulin-like growth factor binding protein-3

OBJECTIVES

To analyze the differences in the plasma levels of insulin-like growth factor-I (IGF-I), IGF-binding protein-3 (IGFBP-3), and their ratio between black and white men while controlling for factors that could confound the relationship between IGF levels and race. Furthermore, we analyzed the association between age, height, prostate-specific antigen level, digital rectal examination status, and current smoking status on IGF levels separately in black and white men. Greater levels of IGF-I and lower levels of IGFBP-3 have been associated with an increased risk of prostate cancer in many studies.

METHODS

A cross-sectional analysis was performed on 171 white and 130 black men aged 40 to 80 years. Multiple linear regression analysis was used to model the data separately for blacks and whites. A chi-square global test was used to test for racial differences in regression curves.

RESULTS

Our results indicated that black men have lower levels of IGFBP-3 and IGF-I and a greater IGF-I/IGFBP-3 ratio than white men across all ages younger than 70, with and without an adjustment for height. We found racial differences in the effect of age and height on levels of IGF-I, IGFBP-3, and the molar ratio. Age had an inverse correlation with IGF-I and IGFBP-3 levels in whites, but no such relationship in blacks.

CONCLUSIONS

The differences in IGF levels between blacks and whites may explain some of the racial disparity in prostate cancer risk. Because age and height affect IGF levels differently in black and white men, future analysis exploring the determinants of IGF levels may need to be stratified by race.

Variation in plasma insulin-like growth factor-1 and insulin-like growth factor binding protein-3: genetic factors

Insulin-like growth factors (IGFs) play key roles in cell proliferation and apoptosis. Whereas relatively stable within individuals, IGFs vary substantially between individuals, and a large component of this variation may be determined by genetic factors. Several polymorphisms in IGF genes have been identified, although their functional significance is not clear. We evaluated the association of polymorphisms in IGF-1 and IGFBP-3 and circulating levels of IGF-1 and IGFBP-3 in 323 population-based control subjects enrolled in a case-control study of colorectal cancer from September 1999 through February 2002. Total IGF-1 and IGFBP-3 levels were measured using ELISA assays, and all subjects were genotyped for a microsatellite polymorphism in IGF-1 and a single nucleotide polymorphism in IGFBP-3. Multiple linear regression was used to assess the association of genotype with circulating IGFs. IGF-1 levels were unrelated to either polymorphism. IGFBP-3 was significantly associated with IGFBP-3 genotype, with IGFBP-3 levels increasing from CC (1,895 ng/mL) --> GC (2,029 ng/mL) --> GG (2,182 ng/mL), (p-trend < 0.001). Having an IGF-1 genotype other than homozygous for the 19-repeat allele was associated with higher IGFBP-3 levels (1,945 versus 2,052 ng/mL). Furthermore, both IGF-1 and IGFBP-3 genotypes modified the relationship between postmenopausal hormone use and IGFs. This analysis provides evidence that common variation in IGF genes may contribute to the variation in circulating levels observed between individuals.

Low-fat high-fiber diet decreased serum and urine androgens in men

To validate our hypothesis that reduction in dietary fat may result in changes in androgen metabolism, 39 middle-aged, white, healthy men (50-60 yr of age) were studied while they were consuming their usual high-fat, low-fiber diet and after 8 wk modulation to an isocaloric low-fat, high-fiber diet. Mean body weight decreased by 1 kg, whereas total caloric intake, energy expenditure, and activity index were not changed. After diet modulation, mean serum testosterone (T) concentration fell (P < 0.0001), accompanied by small but significant decreases in serum free T (P = 0.0045), 5 alpha-dihydrotestosterone (P = 0.0053), and adrenal androgens (androstendione, P = 0.0135; dehydroepiandrosterone sulfate, P = 0.0011). Serum estradiol and SHBG showed smaller decreases. Parallel decreases in urinary excretion of some testicular and adrenal androgens were demonstrated. Metabolic clearance rates of T were not changed, and production rates for T showed a downward trend while on low-fat diet modulation. We conclude that reduction in dietary fat intake (and increase in fiber) results in 12% consistent lowering of circulating androgen levels without changing the clearance.

The Insulin-like Growth Factor System in Cancer Prevention: Potential of Dietary Intervention Strategies

The insulin-like growth factor (IGF) system is related to proliferation and tumor growth, and high levels of circulating IGF-I are thought to be a risk factor for several types of cancer. This review summarizes the epidemiologic evidence for an association between circulating IGF-I and cancer risk as well as the experimental evidence for a causal relation between the endocrine IGF system and tumor growth. The potential for dietary intervention to alter the IGF system and thereby cancer risk is supported by several lines of evidence. Postulated mechanisms of action are as follows: (a) reduction of levels of circulating IGF-I, which will decrease activation of the IGF-I receptor and subsequent signaling pathways; (b) increasing local IGF binding proteins, which may have IGF-dependent effects through obstruction of IGF interaction with local IGF-I receptor as well as IGF-independent effects; and (c) interference with estrogens and estrogen receptor action, which may have direct (and possibly synergistic) effects on IGF signaling. An overview is given of the epidemiologic studies on dietary determinants of circulating IGF-I. Examples of dietary factors, such as dairy protein, lycopene, and phytoestrogens, are used to illustrate the potential mode of action of dietary interventions that may act on the IGF system. In conclusion, the IGF system has every potential to serve as an intermediate for cancer (chemo)prevention studies. On the short term, more research initiatives aimed at the effects of specific food components or dietary strategies on the IGF system both in animal models and in humans are warranted.

Cross-Sectional Associations of Diet and Insulin-Like Growth Factor Levels in 7- to 8-Year-Old Children

Background: The insulin-like growth factors (IGF) are polypeptide hormones which are associated with several adult diseases including cancer and coronary heart disease. The dietary determinants of circulating levels of components of the IGF system are of interest, as these may mediate some of the effects of diet on later health. However, few studies have examined the relationship between diet and IGF levels in children.

Objective: To investigate associations between diet and IGF-I and IGFBP-3 levels in 7- to 8-year-old children.

Methods: This study used subjects participating in the Avon Longitudinal Study of Parents and Children. Diet was assessed using a 3-day unweighed food diary. Confounding variables considered were maternal education, housing tenure, birthweight, and body mass index.

Results: Complete information on dietary intakes, IGF levels, and all confounding variables were available for 521 children (287 boys). IGF-I was positively associated with intakes of protein, magnesium, zinc, calcium, potassium, and phosphorus, and IGFBP-3 was positively associated with energy. The IGF-I/IGFBP-3 ratio was positively associated with intakes of protein, zinc, and phosphorus. There was some evidence that the dietary determinants of the IGF system differed between the sexes. None of the foods examined were strongly associated with IGF levels, in particular, there was no association with red meat or vegetable intake.

Conclusion: These data suggest that the IGF axis in children is affected by diet. This may provide a mechanism whereby childhood diet could have a long-term effect on risk of chronic disease.

Bowel movement frequency, medical history and the risk of gallbladder cancer death: a cohort study in Japan

Few risk factors for gallbladder cancer have been identified with sufficient statistical power, because this cancer is rare. The present study was conducted to evaluate the association of bowel movement frequency and medical history with the risk of death from gallbladder cancer using the data set from a large-scale cohort study. A total of 113,394 participants (42.0% males), aged 40 to 89 years, were followed up for 11 years. Information on the medical history of selected diseases, history of blood transfusions, frequency of stools, and tendency toward diarrhea at baseline was collected through a self-administered questionnaire. The Cox proportional hazard model was used to estimate the hazard ratio (HR). During the follow-up period, a total of 116 deaths (46 males, 70 females) from gallbladder cancer were identified. After adjustments for age and gender, history of hepatic disease (HR: 2.28; 95% confidence intervals (95% CI): 1.24-4.21), frequency of stool, and tendency toward diarrhea (HR: 0.26; 95% CI: 0.08-0.83) were found to be significantly associated with the risk of death from gallbladder cancer. Compared with those who had a stool at least once a day, the HR was 2.06 (95% CI: 0.82-5.18) for those who had a stool less than once in 6 days (P for trend = 0.050). In this prospective study, constipation and a history of hepatic disease were found to elevate the risk of gallbladder cancer death, whereas a tendency toward diarrhea diminished it.

Screen-detected prostate cancer and the insulin-like growth factor axis: results of a population-based case-control study

Higher circulating levels of IGF-I have been associated with increased risk of prostate and some other cancers. Most research on prostate cancer has been based on men with symptoms or identified following treatment of benign disease. However, increasing numbers of cancer cases are now detected in asymptomatic men following prostate-specific antigen (PSA) tests. We therefore used a population-based case-finding exercise using the PSA test to examine whether associations between the IGF axis and cancer risk were apparent in this population. A matched case-control study was conducted among 7,383 men (50-70 years) receiving a PSA test as part of a case-finding exercise. Assays of IGF-I, IGF-II, IGFBP-2 and IGFBP-3 were performed on cases and 2 controls matched on age, recruitment center and calendar time. Analyses were based on 176 cases and 324 matched controls. The risk of prostate cancer increased across quartiles of IGF-I (highest vs. lowest quartile, OR = 2.34; 95% CI = 1.26-4.34; p(trend) = 0.02) and IGF-II (OR = 1.78; 95% CI = 0.94-3.15; p(trend) = 0.09). Controlling for smoking history and IGFBP-3 strengthened associations with cancer for both IGF-I (OR = 3.00; 95% CI = 1.50-6.01; p(trend) 0.005) and IGF-II (OR = 2.02; 95% CI = 1.07-3.84; p(trend) = 0.04) Associations between the IGFs and cancer risk were stronger for advanced cases. Our findings suggest that both IGF-I and IGF-II are associated with an increased risk of screen-detected prostate cancer.

Human prostate cancer risk factors

Prostate cancer has the highest prevalence of any nonskin cancer in the human body, with similar likelihood of neoplastic foci found within the prostates of men around the world regardless of diet, occupation, lifestyle, or other factors. Essentially all men with circulating androgens will develop microscopic prostate cancer if they live long enough. This review is a contemporary and comprehensive, literature-based analysis of the putative risk factors for human prostate cancer, and the results were presented at a multidisciplinary consensus conference held in Crystal City, Virginia, in the fall of 2002. The objectives were to evaluate known environmental factors and mechanisms of prostatic carcinogenesis and to identify existing data gaps and future research needs. The review is divided into four sections, including 1) epidemiology (endogenous factors [family history, hormones, race, aging and oxidative stress] and exogenous factors [diet, environmental agents, occupation and other factors, including lifestyle factors]); 2) animal and cell culture models for prediction of human risk (rodent models, transgenic models, mouse reconstitution models, severe combined immunodeficiency syndrome mouse models, canine models, xenograft models, and cell culture models); 3) biomarkers in prostate cancer, most of which have been tested only as predictive factors for patient outcome after treatment rather than as risk factors; and 4) genotoxic and nongenotoxic mechanisms of carcinogenesis. The authors conclude that most of the data regarding risk relies, of necessity, on epidemiologic studies, but animal and cell culture models offer promise in confirming some important findings. The current understanding of biomarkers of disease and risk factors is limited. An understanding of the risk factors for prostate cancer has practical importance for public health research and policy, genetic and nutritional education and chemoprevention, and prevention strategies.

Do height-related variations in insulin-like growth factors underlie the associations of stature with adult chronic disease?

Tall people, particularly those with long legs, have an increased risk of developing cancer but a reduced risk of cardiovascular disease and type II diabetes. We examined associations of stature and body mass index with IGF-I, IGF-II, and IGF binding protein (IGFBP)-2 and IGFBP-3 in 274 men aged 50-70 yr to investigate whether variations in growth factor levels underlie associations of anthropometry with a number of adult diseases. Height and leg and trunk length were not strongly associated with circulating levels of IGF-I, IGF-II, or IGFBP-3. The molar ratio of IGF-I/IGFBP-3 increased with increases in the leg/trunk length ratio (P = 0.06). IGFBP-2 was positively associated with leg length and inversely associated with trunk length. Mean levels of IGFBP-2 (in nanograms per milliliter) across quartiles of increasing leg length were 504.4 493.6, 528.7, and 578.8 (P(trend) = 0.06), and for trunk length were 615.2, 507.2, 498.6, 488.5 (P(trend) < 0.01), suggesting that variations in IGFBP-2, or a factor influencing its levels in the circulation, may contribute to biological mechanisms underlying height-disease associations. We conclude that whereas growth-influencing exposures during childhood, which may operate through effects on IGF-I levels, have long-term influences on disease risk, they do not necessarily program IGF-I levels throughout life. The associations of anthropometry with IGFBP-2 merit additional investigation.

Tomato products and lycopene supplements: mandatory components in nutritional treatment of cancer patients?

PURPOSE OF REVIEW

This review presents the latest experimental and clinical research focussing on the relationship between the intake of tomato products and lycopene supplementation and carcinogenesis, with the aim of drawing conclusions for concepts of clinical nutritional support.

RECENT FINDINGS

Apart from the preventative role of tomato products/lycopene intake there is evidence that oral supplementation of these compounds in cancer patients may also improve the biomarkers of carcinogenesis and reduce tumour growth. New experimental studies in animal models provide insights concerning the potential mechanism(s).

SUMMARY

Although the first clinical trials are promising, it is too early to make final recommendations for nutritional therapy in cancer patients. Whether the bioactive compound in tomatoes is lycopene or whether other substrates contribute to the beneficial physiological effects is still unclear.

An investigation of fetal, postnatal and childhood growth with insulin-like growth factor I and binding protein 3 in adulthood

OBJECTIVE

Weight at birth and adult height are positively associated with cancer risk. These patterns may be mediated by the insulin-like growth factor (IGF) axis. We have examined whether pre- and postnatal growth patterns have a long-term influence on adult IGF-I and IGFBP-3 levels.

DESIGN

A follow-up study of a randomized controlled trial of milk supplementation in pregnancy and childhood.

SUBJECTS

A total of 951 individuals took part in a study of diet and growth in South Wales between 1972 and 1974 followed up from birth until their mid-20s.

MEASUREMENTS

Anthopometric measures at birth, postnatally up to 5 years of age and in adulthood, and serum measures of IGF-I and IGF-I to IGFBP-3 ratio at mean age of 25 years.

RESULTS

A total of 63 subjects (70%) provided blood for analysis. We found no association between birth dimensions and adult IGF-I. Subjects who exhibited 'catch-down growth' had lower IGF-I levels (P-value for trend 0.02). Adult height was positively related to IGF-I, for every one standard deviation increase in adult height, IGF-I increased by 3.75 ng/dl (95% CI 0.46-7.08, P = 0.03). Adiposity was inversely associated with the IGF-I and IGF-I to IGFBP-3 ratio and positively associated with IGFBP-3. The strength of the associations increased with age. Downward centile crossing at any time in childhood was associated with lower IGF-I whilst the highest levels were observed in subjects who were tall throughout their early life course. Adult height remained a significant predictor of IGF-I even after adjustment for earlier growth.

CONCLUSIONS

Our results indicate that IGF-I levels in early adulthood are associated with patterns of childhood growth as well as adult stature and adiposity. These associations suggest the IGFs may contribute to anthropometric associations with cancer risk.

Are diet-prostate cancer associations mediated by the IGF axis? A cross-sectional analysis of diet, IGF-I and IGFBP-3 in healthy middle-aged men

We examined the association of diet with insulin-like growth factors (IGF) in 344 disease-free men. Raised levels of IGF-I and/or its molar ratio with IGFBP-3 were associated with higher intakes of milk, dairy products, calcium, carbohydrate and polyunsaturated fat; lower levels with high vegetable consumption, particularly tomatoes. These patterns support the possibility that IGFs may mediate some diet-cancer associations.

Dietary and lifestyle factors in relation to plasma insulin-like growth factor I in a general population sample

There is evidence that the insulin-like growth factor system (IGF), particularly IGF-I, is important in human carcinogenesis. We studied in a general, though not strictly random population sample of 620 adults, the relationship of IGF-I to demographic, lifestyle and dietary factors, the latter ascertained through an extensive validated questionnaire. Plasma IGF-I levels declined significantly with age and the decline was more evident among women than among men. Tobacco smoking, body mass index and regular physical activity were unrelated to this hormone and a positive association with height was not statistically significant. Neither protein nor carbohydrate intake was related to plasma IGF-I levels but there was inconsistent evidence that ethanol intake may be inversely associated with plasma IGF-I and saturated and polyunsaturated lipids may be positively associated with it. The findings are evaluated in conjunction with evidence indicating that the incidence of cancer is lower among women than among men, height is a risk factor for several forms of cancer, and saturated and polyunsaturated lipids have been more closely linked to human and animal carcinogenesis than monounsaturated lipids.

Are dietary influences on the risk of prostate cancer mediated through the insulin-like growth factor system?

OBJECTIVES

To investigate whether dietary factors that appear to affect the risk of prostate cancer may be similarly associated with serum levels of insulin-like growth factor 1 (IGF-1). Patients and methods In the context of a case-control study, 112 men were admitted to three teaching hospitals in Athens, Greece, for disorders other than cancer. Sociodemographic data and detailed histories of smoking, alcohol and coffee consumption were recorded. A validated food-frequency questionnaire was administered by an interviewer and serological measurements of IGF-1 and its binding protein-3 conducted.

RESULTS

IGF-1 declined significantly by almost 25% among men aged >75 years and there was a small reduction in IGF-1 levels with increased alcohol intake, with a mean (95% confidence interval, CI) change of -1.6 (- 2.2 to -0.9)% for an increment of one drink per day. There was no evidence for an effect of either smoking or coffee consumption on IGF-1 level. Among foods, the consumption of cooked tomatoes was substantially and significantly inversely associated with IGF-1 levels, with a mean (95% CI) change of -31.5 (- 49.1 to -7.9)% for an increment of one serving per day.

CONCLUSIONS

The strongest known dietary risk factor for prostate cancer (lycopene deficit, as reflected in a reduced intake of cooked tomatoes) and an important endocrine factor in the aetiology of this disease (IGF-1) seem to be related in a way that suggests that at least one, and perhaps more, exogenous factors in the development of prostate cancer may be mediated through the IGF-1 system.