Effect of obesity on prostatic hyperplasia: its relation to sex steroid levels

Expression and functional activity of myosin II in hyperplastic prostates of varying volumes

Prostate volume (PV) differs dramatically among benign prostatic hyperplasia (BPH) patients. Estimation of PV is important to guide the most appropriate pharmacologic or interventional treatment approach. However, the underlying pathophysiological mechanisms for the differences in PV remain unknown. We recently found that the myosin II system might participate in the etiology and development of BPH via static and dynamic factors. Our present study aims to explore the expression and functional activities of myosin II isoforms including smooth muscle (SM) myosin II (SMM II) and non-muscle myosin II (NMM II) in hyperplastic prostates with varied PV. Human hyperplastic prostates and the testosterone-induced rat BPH model were employed for this study. Hematoxylin and Eosin (H&E), Masson's trichrome, immunohistochemical staining, in vitro organ bath, RT-polymerase chain reaction (PCR) and Western-blotting were performed. Also, a BPH tissue microarray (TMA) was constructed to determine the correlations between myosin II isoforms with clinical parameters of BPH patients. With the increase of PV, the expression of NMMHC-A, NMMHC-C, SM-A and LC_17b isoforms were increased, and the contractility of prostate smooth muscle was enhanced but force developed more slowly. Consistently, NMMHC-A, NMMHC-C, SM-A and LC_17b were correlated positively with PV. Similar outcomes were also observed in the BPH rat model with different PVs. Alterations in the expression and function of myosin the II system may be involved in the pathophysiological mechanism of PV differences between BPH patients.

Obesity and benign prostatic hyperplasia: clinical connections, emerging etiological paradigms and future directions

PURPOSE

Benign prostatic hyperplasia is a highly prevalent disease in older men with substantial adverse effects on public health. Classic etiological paradigms for benign prostatic hyperplasia focus on nonmodifiable risk factors. However, obesity also potentially promotes benign prostatic hyperplasia.

MATERIALS AND METHODS

We performed a structured, comprehensive literature review to identify studies of obesity, benign prostatic hyperplasia, lower urinary tract symptoms and physical activity.

RESULTS

A preponderance of published evidence suggests strong positive associations of obesity with benign prostatic hyperplasia and lower urinary tract symptoms. This evidence encompasses most established metrics of adiposity, including body mass index, waist circumference and waist-to-hip ratio, and falls under 3 general categories, including prostate volume, clinical benign prostatic hyperplasia and lower urinary tract symptoms. 1) Prior studies consistently showed that increased adiposity is positively associated with radiographically determined prostate volume and enlargement, suggesting that obesity promotes prostate growth. 2) Most studies revealed that obesity increases the risk of clinical benign prostatic hyperplasia by several measures, including the initiation of benign prostatic hyperplasia medical treatment, noncancer prostate surgery, physician diagnosed benign prostatic hyperplasia, histological diagnosis and urinary flow rate. 3) Prior studies demonstrated that obesity increases the risk of lower urinary tract symptoms, as measured by a validated questionnaire. Also, most studies showed that physical activity significantly decreases the risk of benign prostatic hyperplasia.

CONCLUSIONS

Obesity markedly increases the risk of benign prostatic hyperplasia. Since physical activity decreases the risk of benign prostatic hyperplasia, these observations support the development of novel prevention strategies and treatment targeted toward adiposity, weight loss and lifestyle.

Which obesity index best correlates with prostate volume, prostate-specific antigen, and lower urinary tract symptoms?

OBJECTIVE

To determine which measurement variable, waist circumference (WC), body mass index (BMI), or waist-to-hip ratio (WHR) is most closely related to the prostate volume (PV), prostate-specific antigen (PSA), and lower urinary tract symptoms (LUTS).

METHODS

Between January 2010 and September 2011, 1632 consecutive ostensibly healthy Korean men aged 40-69 years who visited our clinic for a prostate checkup were enrolled into the study. Exclusion criteria included pyuria, history of lower urinary tract disorder influencing urination, and a high PSA level of >3.0 ng/mL. All men underwent a detailed clinical evaluation using the International Prostate Symptom Score (I-PSS) questionnaire. Anthropometric measurements were determined. Serum PSA, urinalysis, and transrectal ultrasound were also performed.

RESULTS

Data from 1601 men were analyzed. The mean age was 51.6 years, WC 83.7 cm, BMI 24.8 kg/m(2), PV 24.6 mL, and the mean PSA level was 1.07 ng/mL. Using multivariate analysis, PV most positively associated with WC (P < .001), while PSA level had negatively associated with BMI (P = .036) and no significant association with WC or WHR was noted. There was no significant relationship between various obesity indexes and I-PSS.

CONCLUSION

Our data showed that PV positively associated with central obesity, as represented by WC. In contrast, serum PSA negatively associated with BMI, which represented overall obesity (ie, hemodilution). Our data also suggested that obesity is not associated with lower urinary tract symptoms in Korean men.

Parathyroid hormone is not involved in prostate growth in patients with benign prostatic hyperplasia

BACKGROUND

A recent population-based study reported that serum calcium and parathyroid hormone stimulate prostate growth. We evaluated whether serum PTH, vitamin D, and calcium levels correlate with prostate size, PSA levels, and obesity in Korean patients with histologically proven BPH.

METHODS

Patients with histopathologically proven BPH who underwent transurethral resection of the prostate were enrolled (n = 289). Patients with PSA levels of ≥3 ng/ml underwent multicore transrectal prostate biopsy before TURP to rule out prostate cancer. Patients with serum creatinine levels >1.4 mg/dl, PSA levels >20 ng/ml, and/or PTH levels <10 pg/ml were excluded. Correlations between serum parameters and clinical data were determined. After adjustment for potential confounders, including age and body mass index, multiple linear regression served to compute associations.

RESULTS

The mean age, serum PSA level, PTH level, and prostate size were 68.13 ± 7.15 years, 4.10 ± 3.88 ng/ml, 24.33 ± 12.52 pg/ml, and 44.27 ± 24.15 g, respectively. Prostate size correlated positively with age (r = 0.209, P < 0.001) and PSA levels (r = 0.481, P < 0.001), and PSA levels correlated positively with age (r = 0.226, P < 0.001) and prostate size (r = 0.481, P < 0.001), but neither variable correlated with PTH, vitamin D, calcium levels, or BMI. Upon multiple adjusted linear regression analysis, prostate size correlated with BMI and serum PSA (both P < 0.001), and serum PSA levels correlated with BMI and prostate size (P = 0.007, P < 0.001, respectively), but neither variable correlated with PTH, vitamin D, or serum calcium levels.

CONCLUSIONS

In Korean patients with histopathologically proven BPH, high PTH, vitamin D, and calcium levels do not stimulate prostate growth.

PPARγ: a molecular link between systemic metabolic disease and benign prostate hyperplasia

The emergent epidemic of metabolic syndrome and its complex list of sequelae mandate a more thorough understanding of benign prostatic hyperplasia and lower urinary tract symptoms (BPH/LUTS) in the context of systemic metabolic disease. Here we discuss the nature and origins of BPH, examine its role as a component of LUTS and review retrospective clinical studies that have drawn associations between BPH/LUTS and type II diabetes, inflammation and dyslipidemia. PPARγ signaling, which sits at the nexus of systemic metabolic disease and BPH/LUTS through its regulation of inflammation and insulin resistance, is proposed as a candidate for molecular manipulation in regard to BPH/LUTS. Finally, we introduce new cell and animal models that are being used to study the consequences of obesity, diabetes and inflammation on benign prostatic growth.

Diet, physical activity and energy balance and their impact on breast and prostate cancers

Obesity, physical activity status and circulating levels of sex steroid hormones and growth factor proteins are intrinsically linked to energy balance. Epidemiological studies have previously reported associations between these factors and the risk of hormone-related cancers such as prostate and breast cancer in men and postmenopausal women. An increasing number of intervention studies in 'at-risk' populations and cancer survivors are now investigating the effects of lifestyle interventions that promote negative energy balance on circulating levels of sex hormones and growth factor proteins as surrogate markers of cancer risk. Evidence from these studies suggests that lifestyle interventions can improve insulin sensitivity, alter the balance of circulating sex steroid hormones and insulin-like growth factor (IGF) axis proteins (including IGF-1 and the IGF binding proteins 1 and 3) and change the functioning of immune cells in peripheral blood. Such changes could influence the risk of developing hormone-related cancers, as well as having the potential to improve disease-free survival in patients recovering from cancer treatment. However, despite promising results, the methodological quality of most intervention studies has been limited due to small subject numbers, lack of adequate control groups or non-randomised designs and the absence of long-term follow-up measures. More intervention studies with randomised controlled designs, higher numbers of subjects and longer-term follow-up measures are needed to establish which combination of specific dietary and physical activity interventions work best for reducing risk in 'at-risk' populations and survivors, optimal dose-response relationships and the magnitude of change in surrogate markers of cancer risk that is required to induce a protective effect.

Metabolic syndrome in sub-Saharan Africa: "smaller twin" of a region's prostatic diseases?

Prostate cancer (PC) and benign prostate hyperplasia (BPH) constitute many of the health concerns of males around the world. Prostate cancer is the major cause of death after lung cancer in men. Benign prostate hyperplasia affects most males above 40 years of age. A variety of factors, chiefly age, genetics and lifestyle, have been linked to the development of PC and BPH. The metabolic syndrome describes a chain of chronic disorders that are inter-related in aetiology, and result from unhealthy lifestyles, often due to an affluent economy. The eating of processed foods and a sedentary lifestyle apparently are status symbols among the middle and upper classes in sub-Saharan Africa. These have resulted in a surge in the disease burden of sub-Saharan Africa. This paper looks at the aetiology and prevalence of the metabolic syndrome and prostatic diseases, especially in sub-Saharan Africa. Evidence from the available literature shows that prostate disorders may be related to the metabolic syndrome. There is a likelihood that if sub-Saharan Africans keep copying the lifestyles of the developed world, especially in the direction of the nature of food items consumed, then the rising prevalence of diseases of the metabolic syndrome and the attendant prostate disorders may become very formidable healthcare "twin" problems for the region.

Modifiable risk factors for benign prostatic hyperplasia and lower urinary tract symptoms: new approaches to old problems

PURPOSE

Benign prostatic hyperplasia is generally not regarded as a preventable disease. However, accumulating evidence suggests that modifiable factors may influence the risk of benign prostatic hyperplasia and lower urinary tract symptoms.

MATERIALS AND METHODS

A structured, comprehensive literature review was done to identify modifiable risk factors for benign prostatic hyperplasia and lower urinary tract symptoms among observational studies of older men.

RESULTS

Outcome measures used to define benign prostatic hyperplasia in clinical studies include histological analysis of prostate tissue, radiographically determined prostate enlargement, acute urinary retention, decreased urinary flow rate, pressure flow studies consistent with bladder outlet obstruction, history of benign prostatic hyperplasia surgery, physician diagnosed benign prostatic hyperplasia and American Urological Association symptom score or International Prostate Symptom Score. Factors that potentially increase the risk of benign prostatic hyperplasia and lower urinary tract symptoms include obesity and diabetes. Factors that potentially decrease the risk include increased physical activity and moderate alcohol consumption. Other candidate factors for which clear risk patterns have not yet emerged are dyslipidemia, hypertension, smoking, diet and environment.

CONCLUSIONS

Obesity, diabetes, physical activity and alcohol intake may substantially influence the risk of benign prostatic hyperplasia and lower urinary tract symptoms in older men. Further analyses of these and other potential modifiable risk factors may identify novel interventions for the prevention, diagnosis and treatment of these highly prevalent conditions.

Prostate volume modifies the association between obesity and prostate cancer or high-grade prostatic intraepithelial neoplasia

The relationship between obesity and prostate cancer remains unclear. We investigated the effect of prostate volume on the obesity and prostate cancer association. With a multi-centered, rapid-recruitment protocol, weight and body size measurements were collected prior to diagnosis, and medical charts were reviewed for pathology results (n = 420 controls, 119 high-grade prostatic intraepithelial neoplasia (PIN) cases, and 286 cancer cases (41% Gleason > 6). In multivariable logistic regression models adjusting for age, PSA levels and history, DRE results, and number of cores at biopsy, the association between BMI and cancer was restricted to men with a smaller prostate volume (volume < 40 cm(3): OR(BMI > or = 30) = 2.17 (1.09, 4.32), p (trend) = 0.02; volume > or = 40 cm(3): OR(BMI > or = 30) = 0.77 (0.34, 1.77), p (trend) = 0.17; p (interaction) = 0.03). Similarly, the WHR and PIN association was significantly modified by prostate volume (volume < 40 cm(3): OR((WHR: Tertile 3 vs. T1)) = 3.76 (1.54, 9.21) (p (trend) < 0.01); volume > or = 40 m(3): OR((WHR: T3 vs. T1)) = 0.63 (0.32, 1.23) (p (trend) = 0.17); p (interaction) < 0.01). In conclusion, prostate volume acts as a modifier, and BMI and WHR are significantly associated with prostate cancer or PIN, respectively, in the absence of biopsy sampling error derived from obesity-related prostate enlargement.

The association between body size, prostate volume and prostate-specific antigen

Increasing prostate volume contributes to urinary tract symptoms and may obscure prostate cancer detection. We investigated the association between obesity and prostate volume, prostate-specific antigen (PSA) and PSA density among 753 men referred for prostate biopsy. Among men with a negative biopsy, prostate volume significantly increased approximately 25% from the lowest to highest body mass index (BMI), waist or hip circumference or height categories. PSA was 0.7 ng/ml lower with a high waist-to-hip ratio. These associations were less consistent among subjects diagnosed with high-grade prostatic intraepithelial neoplasia or cancer. Our data suggest that obesity and height are independently associated with prostate volume..

Metabolic factors associated with benign prostatic hyperplasia

CONTEXT

Benign prostatic hyperplasia poses a significant public health problem, but its etiology remains unclear. Obesity and associated abnormalities in glucose homeostasis may play a role in benign prostatic hyperplasia development by influencing prostate growth.

OBJECTIVE

The objective of this study was to determine whether obesity, fasting plasma glucose concentration, and diabetes are associated with radiologically determined prostate enlargement, an objective measure of benign prostatic hyperplasia.

DESIGN

This study was a cross-sectional analysis with robust variance estimates to account for multiple measures over time in the same individuals.

SETTING

This prospective cohort study was composed of community volunteers.

PATIENTS

Patients studied were 422 adult men enrolled in The Baltimore Longitudinal Study of Aging.

MAIN OUTCOME MEASUREMENTS

Total prostate volume as determined by pelvic magnetic resonance imaging was measured.

RESULTS

Among 422 participants, 91 (21.6%) had prostate enlargement (defined as total prostate volume >/= 40 cc) at first visit. Compared with men of normal weight [body mass index (BMI) < 25 kg/m(2)], the age-adjusted odds ratio (OR) for prostate enlargement for overweight men (BMI, 25-29.9 kg/m(2)) was 1.41 (95% CI, 0.84-2.37), for obese men (BMI, 30-34 kg/m(2)) was 1.27 (95% CI, 0.68-2.39), and for severely obese men (BMI >/= 35 kg/m(2)) was 3.52 (95% CI, 1.45-8.56) (P = 0.01). Men with elevated fasting glucose (>110 mg/dl) were more likely to have an enlarged prostate than men with normal fasting glucose (

CONCLUSIONS

Obesity, elevated fasting plasma glucose, and diabetes are risk factors for benign prostatic hyperplasia.

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Key Words Collapse

MESH Headings

• Adult
• Aged
• Aged, 80 and over
• Black People
• Blood Glucose/analysis
• Body Mass Index
• Cohort Studies
• Cross-Sectional Studies
• Diabetes Complications
• Ethnicity
• Humans
• Longitudinal Studies
• Male
• Middle Aged
• Obesity/complications
• Odds Ratio
• Prospective Studies
• Prostate/pathology
• Prostatic Hyperplasia/etiology
• Prostatic Hyperplasia/metabolism
• Prostatic Hyperplasia/pathology
• Testosterone/blood
• Urologic Diseases/etiology
• Waist-Hip Ratio
• White People

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Grants

• Z01 AG000015-49 Intramural NIH HHS

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Affiliation(s)

J Kellogg Parsons Division of Urology, University of California San Diego, 200 West Arbor Drive, San Diego, California 21287, USA.
H Ballentine Carter
Alan W Partin
B Gwen Windham
E Jeffrey Metter
Luigi Ferrucci
Patricia Landis
Elizabeth A Platz

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Serum lipid levels in benign prostatic hyperplasia

The relationship between serum lipid levels and measures of benign prostatic hyperplasia was investigated. The study was community based. All the participants had undergone a urological investigation which included International Prostate Symptom Score (I-PSS) and Quality of Life Score (QoL), serum lipid concentrations and determination of prostate volume with transrectal ultrasonography. Body mass index was calculated with the formula of weight (kg)/surface area (m(2)) respectively. Men were considered obese if their body mass index was over 25 kg/m(2). BPH was defined by prostate volume greater than 20 ml and I-PSS greater than seven. Comparisons of serum lipid levels between men with BPH and without BPH were done. There was no correlation for serum lipid levels with either mean I-PSS and QoL scores. However, triglyceride and cholesterol levels were the lowest in severe symptomatic men than men with low symptoms. Using clinical definition of BPH that prostate volume was greater than 20 ml and I-PSS was greater than seven, men with BPH had not significantly different serum lipid levels from men without BPH. Our population-based data reflect that there was no relationship between serum lipid levels and certain physiological measures of lower urinary tract symptoms and clinical benign prostatic hyperplasia.

Risk Factors for Benign Prostatic Hyperplasia in South Korean Men

OBJECTIVES

Benign prostatic hyperplasia (BPH) is the most common prostate disease in middle-aged and elderly men, and leads to severe impairment in later life. Despite the significant effect on public health, the causes of BPH have received little attention. Identifying risk factors for BPH is crucial for understanding the etiology and for determining effective interventions or targeting strategies.

METHODS

This survey was performed in two steps: (1) a pilot study was first conducted prior to the main study in order to estimate baseline characteristics, and (2) the main study investigated the prevalence and risk factors of BPH using clinical diagnostic tests and a questionnaire. A total of 641 males, aged 50-79 years, participated in this community-based cross-sectional study.

RESULTS

Age was the only significant demographic risk factor of BPH. The presence of chronic bronchitis and a high prostate-specific antigen (PSA) level increased the risk by three- and twofold, respectively. The risk decreased as drinking frequency increased. Physical activity 3-5 times/week reduced the risk relative to being active less than twice per week; however, engaging in physical activity nearly everyday increased the risk 1.7-fold relative to being active up to twice per week.

CONCLUSIONS

Although BPH has been considered a disease that is unavoidable with advancing age, the clear identification and control of the underlying risk factors might allow effective prevention by placing a special emphasis on those at risk.

Central obesity as a risk factor for prostatic hyperplasia

OBJECTIVE

Obesity-related metabolic diseases may influence prostatic hyperplasia. This study examined the impact of obesity on prostate volume in men without overt obesity-related metabolic diseases.

RESEARCH METHODS AND PROCEDURES

We recruited 146 men over the age of 40 years who did not have overt obesity-related diseases, such as diabetes, impaired fasting glucose, hypertension, or dyslipidemia. Transrectal ultrasonography was performed on all subjects. The subjects were divided into three groups according to their BMI: normal (18.5 to 22.9 kg/m2), overweight (23 to 24.9 kg/m2), and obese (> or = 25 kg/m2), and two groups according to their waist circumference: normal waist (< or = 90 cm) and central obesity (> 90 cm). The classification of the subgroups was based on the Asia-Pacific criteria of obesity. We compared the prostate volume among subgroups and assessed factors related to prostatic hyperplasia.

RESULTS

Mean prostate volume was 18.8 +/- 5.0, 21.8 +/- 7.2, and 21.8 +/- 5.6 mL in the normal, overweight, and obese groups, respectively, and was 20.0 +/- 5.9 and 23.7 +/- 5.3 mL in the normal waist and central obesity group, respectively. Prostate volume was significantly greater in the obese group than in the normal group (P = 0.03) and in the central obesity group compared with the normal waist group (P = 0.002). Prostate volume was positively correlated with BMI and waist circumference after adjustment for age. After adjusting for confounding factors, central obesity was an independent factor affecting prostatic hyperplasia, which was defined as a prostate volume > 20 mL (odds ratio = 3.37, p = 0.037). Relative to men with both low BMI (18.5 to 22.9 kg/m2) and normal waist circumference, those with high BMI (> or = 25 kg/m2) and central obesity were at significantly increased risk of prostatic hyperplasia (odds ratio = 4.88, p = 0.008). However, those with high BMI (> or = 25 kg/m2) and normal waist circumference were not at significantly increased risk.

DISCUSSION

Prostate volume was greater in the obese and central obesity groups than in the normal group after patients with overt obesity-related metabolic diseases were excluded. Although both BMI and waist circumference were positively correlated with prostate volume, central obesity was the only independent factor affecting prostate hyperplasia. We suggest that central obesity is an important risk factor for prostatic hyperplasia.

The impact of obesity in urology

The incidence and progression of urologic diseases, as well as several urologic cancers.depend on many interrelated factors, such as obesity, diet, genetics, environment, age, and the immune system. Obesity is a risk factor for stress urinary incontinence, ED, infertility, and renal calculi. Numerous publications have demonstrated that a high dietary intake of fat increases prostate cancer risk, although the mechanisms are not clear. Although some reports may demonstrate an association between obesity and prostate cancer, it may be hard to establish because, in general, men with obesity have a high-fat diet. Obesity, recurrent urinary tract infections, increased intake of protein and fried foods, and female sex seem to increase the risk of renal cancer. Environmental toxins seem to be the major factors affecting the incidence of bladder cancers. Thus, dietary modification and other public health measures directed at reducing weight may reduce the incidence of urologic illnesses. More studies are necessary to determine the therapeutic effects of weight loss and dietary modification on the incidence and progression of urologic tumors.

Testosterone metabolism, dose-response relationships and receptor polymorphisms: selected pharmacological/toxicological considerations on benefits versus risks of testosterone therapy in men

In this review selected toxicological problems related to testosterone therapy in hypogonadal men are discussed. Applying "classical" pharmacological/toxicological findings (e.g. animal studies on short- and long-term toxicity) to clinical situations is not very helpful. Molecular biological knowledge and especially evaluation of epidemiological studies, as well as intervention studies, on testosterone therapy in hypogonadal men are more useful. Potential risks include overdosage for lifestyle reasons, e.g. excessive muscle building and reduction of visceral obesity, when erythrocytosis occurs concomitantly. Modern galenic formulations of testosterone administration (e.g. transdermal gel, suitable testosterone esters for intramuscular application and newer oral preparations) avoid supraphysiological serum concentrations, therefore significantly reducing the toxicological risk. A hypothetical model of the toxicological risks of testosterone therapy is given that is based on the influence of testosterone metabolism (aromatization vs. reduction) of the respective parameter/target chosen. Finally, the great influence of polymorphisms of the androgen receptor on the assessment of toxicological risk and on the individualization of androgen therapy is shown. Already existing national, continental and international guidelines or recommendations for the testosterone therapy should be harmonized.

Relationship of serum sex-steroid hormones and prostate volume in African American men

BACKGROUND

Previous epidemiologic investigations of the associations of sex-steroid hormones and benign prostatic hyperplasia (BPH) have focused on predominately white populations. The objective of this study was to evaluate potential associations of body mass index (BMI), cigarette smoking, use of alcohol, and endogenous sex-steroid hormones with prostate volume in a population-based sample of African American (AA) men, ages 40-79 yr.

METHODS

A total of 369 AA men without clinical evidence of prostate cancer were identified in the Flint Men's Health Study by using a population-based sampling procedure. All subjects underwent a complete urologic evaluation that included prostate volume determination by transrectal ultrasonography and serum assays for androgens and estrogens.

RESULTS

After age adjustment, BMI (weight (kg)/height (m)2) was positively correlated with increasing levels of androstanediol glucuronide (AG), estradiol (E2), estrone sulfate (E1S), and the ratios of E2:total testosterone (TT) and E2:free testosterone (FT); however, increasing BMI was negatively correlated with androstenedione (AD), FT, TT, and sex hormone-binding globulin (SHBG). Multivariable regression models demonstrated that prostate volume increased with age (P < 0.001) and BMI (P = 0.02) and decreased with increasing levels of SHBG (P = 0.01). Larger prostatic volumes were also marginally associated with increasing levels of TT (P = 0.058).

CONCLUSION

Circulating serum levels of SHBG and endogenous sex-steroid hormones are correlated with prostate volume and potentially impact the natural history of BPH. However, longitudinal studies are needed to demonstrate the temporal relationships of hormones and growth factors in the pathogenesis of BPH in AA men.

Is obesity a risk factor for prostate cancer, and does it even matter? A hypothesis and different perspective

Measurement of obesity is not as simple as its definition. Currently, several methods of measuring obesity are used in clinical studies. Skinfold thickness, crude weight, lean body mass (LBM), body mass index (BMI), and waist-to-hip ratio (WHR) are some of the more popular methods, but each contains its inherent strengths and flaws. In general, the results of the largest studies on prostate cancer and obesity have not been conclusive. One of the largest studies found an inverse relation to prostate cancer in the youngest age groups. The age and duration of obesity or any rapid changes in weight gain, along with other unhealthy exposures, may have some relation to prostate cancer incidence and mortality. Early intrinsic or extrinsic exposure to estrogen or estrogenlike compounds may provide a protective effect. The timing and duration of a higher estrogen and/or lower testosterone exposure may have a beneficial or detrimental impact on the prognosis of an established prostate tumor. Negative exposures over time such as low levels of sex hormone-binding globulin (SHBG), a greater exposure to growth factors, elevated insulin levels, greater sympathetic activity, higher cholesterol levels, immune system dysfunction, inadequate diets, smoking status, and other factors may be associated with an increased risk of prostate cancer and other diseases. Obesity may also be associated with other cancers for similar and different reasons. For example, morbidity and mortality from postmenopausal breast cancer, colon, kidney, and other cancers are potentially associated with obesity. Other comorbidities such as cataracts, coronary heart disease, diabetes, erectile dysfunction, hypertension, and others are also associated with obesity. The 2 largest prospective studies on BMI and overall mortality have also demonstrated the substantial negative impact of excess weight on society. Prostate cancer risk and obesity need further research to establish if a true association exists, but at this time, does it really matter? Overall, the profound adverse effect of being obese on general health is dramatic, and this is what clinicians and patients need to remember.

Insulin-like growth factor-1, insulin-like growth factor binding protein-3, and body mass index: clinical correlates of prostate volume among Black men

OBJECTIVES

To examine the relationship between insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), and body mass index and prostate volume, as a surrogate marker for benign prostatic hyperplasia, in a community-based sample of black men. Epidemiologic studies examining the role of IGF-1 and IGFBP-3 suggest that increased levels of serum IGF-1 and decreased levels of serum IGFBP-3 are associated with an increased risk of prostate cancer. Few studies have examined these factors with respect to benign prostatic hyperplasia, and these have been limited to white men.

METHODS

The study population consisted of a sample of 364 black men, 40 to 79 years of age, residing in Genesee County, Michigan. Men with prostate cancer or prior prostate surgery were excluded. All subjects completed a clinical examination, which included a complete urologic examination with transrectal ultrasonography, anthropometric measurements, and serum assays for IGF-1 and IGFBP-3.

RESULTS

Multivariable regression models demonstrated that prostate volume increased with increasing age (P <0.0001) and body mass index (P = 0.03). IGFBP-3 rather than IGF-1 was positively associated with increasing prostate volume (P = 0.003).

CONCLUSIONS

This is the largest study describing the relationships between IGF-1, IGFBP-3, and body mass index and prostate volume, and the only study in black men. Although earlier studies demonstrated an association between IGF-1 and prostate cancer risk, our findings indicate that IGFBP-3 is more relevant for prostate enlargement, suggesting that IGF-1 and IGFBP-3 may play different pathophysiologic roles in benign and malignant prostatic conditions.

Risk factors for clinical benign prostatic hyperplasia in a community-based population of healthy aging men

We defined risk factors for a clinical diagnosis of benign prostatic hyperplasia (BPH) among subjects of the population-based Massachusetts Male Aging Study. In 1987-89 1709 men aged 40-70 provided baseline risk factor data and were followed for a mean of 9 years; 1019 men without prostate cancer provided follow-up data. We classified men with clinical BPH at follow-up if they reported (1) frequent or difficulty urinating and were told by a health professional that they had an enlarged or swollen prostate or (2) if they reported having surgery for BPH. At follow-up the prevalence of clinical BPH was 19.4%, increasing from 8.4% of men aged 38-49 years to 33.5% of men aged 60-70 years (P < 0.001 for trend). Elevated free PSA levels (age- and total PSA-adjusted OR, top vs. bottom quartile ng/mL 4.4, 95% CI 1.9-10.5), heart disease (age-adjusted OR 2.1, CI 1.3-3.3), and use of beta-blocker medications (OR 1.8, CI 1.1-3.0) increased odds for BPH, while current cigarette smoking (OR 0.5, CI 0.3-0.8) and high levels of physical activity (top vs. bottom quartile kcals/day OR 0.5, CI 0.3-0.9) decreased odds of BPH. All but the medication effects persisted in fully adjusted multivariable models. Total or fat calorie intake, sexual activity level, alcohol intake, body mass index, waist-hip ratio, diastolic blood pressure, a history of diabetes, hypertension, vasectomy, or serum levels of androgens or estrogens did not individually predict clinical BPH. We conclude that physical exercise and cigarette smoking appear to protect against development of clinical BPH. Elevated free PSA levels predict clinical BPH independent of total PSA levels. Risk associated with heart disease does not appear to be due solely to detection bias or to effects of heart disease medications. A wide variety of other characteristics appear to have no influence on risk for clinical BPH.

Proliferation and differentiation of rat dorsal prostatic epithelial cells in collagen gel matrix culture, focusing upon effects of adipocytes

BACKGROUND

Prostatic epithelial cells organize functional acinus structures under epithelial extracellular matrix and epithelial-stromal cell interactions. Recently, the adipose tissue, which surrounds and even exists within the prostate, has been suggested to affect the differentiation and proliferation of some cell types. Therefore, tissue fragments, which consist mainly of epithelial and fibromuscular stromal cells, were cultured in three-dimensional collagen gel matrix culture with adipocytes.

METHODS

Tissue fragments of rat dorsal prostate, including both epithelial and fibromuscular stromal components, were cultured in collagen gel with or without adipocytes. Epithelial cell differentiation was evaluated with the reconstruction of acinus-like structures and with immunohistochemistry of rat dorsal prostate-specific proteins, dorsal protein-1 and probasin. The proliferation was examined by uridine uptake.

RESULTS

Under coculture of the fragments and adipocytes, epithelial cells reconstructed more differentiated acinus-like structures surrounded by fibromuscular stromal cells than tissue fragment culture without adipocytes. Dorsal protein-1 and probasin expressions of epithelial cells in this coculture system were the same as in rat prostate in vivo. In the coculture, epithelial cells had a higher proliferation activity.

CONCLUSION

These results indicate that adipocytes promote proliferation and differentiation of prostatic epithelial cells. Our new culture model with adipocytes suggests the importance of cell-cell interactions, including those of epithelial cells and adipocytes.

The epidemiology of benign prostatic hyperplasia: a study in Greece

OBJECTIVE

To assess the epidemiology of benign prostatic hyperplasia (BPH) in a case-control study in greater Athens, Greece.

PATIENTS AND METHODS

The study comprised 184 patients surgically treated for BPH within one year of its diagnosis (cases) and 246 patients with no symptoms of BPH who were treated in the same hospitals for minor diseases or conditions (controls). All cases and controls were permanent residents of the greater Athens area, Greece. The data were assessed using unconditional logistic regression.

RESULTS

After controlling for age and education, cases and controls had similar distributions for height, body mass index, sibship size and birth order in the parental family, marital status, number of offspring and a series of previous medical diagnoses or surgical operations. The sole exception was surgery for haemorrhoids, that appeared to be related to the incidence of BPH, possibly by chance. There was no evidence that vertex baldness, tobacco smoking, alcohol consumption or coffee drinking increased the risk for BPH. Men who had spent most of their lives in a rural rather than an urban environment appeared to be at reduced risk for BPH.

CONCLUSION

The lifestyle factors assessed here have no major effect on the aetiology of BPH.

Effect of obesity on estradiol level, and its relationship to leptin, bone maturation, and bone mineral density in children

The purpose of this study was to investigate 24-h estradiol and leptin levels in obese and nonobese children to further understand the roles of estradiol and leptin in obesity and puberty. We measured serum estradiol, leptin, insulin, glucose, and GH levels every hour for 24 h in 18 obese (12 females and 6 males) and 30 nonobese (11 females and 19 males) prepubertal and early pubertal (stages 1-2) children. Bone age and dual energy x-ray absortiometry (DEXA) were obtained upon completion of the 24-h study. Obese children were significantly younger than nonobese children, with no difference in pubertal stage, height, or bone age between the 2 groups. Obese children had greater bone age to chronological age ratios than nonobese children, indicating a more advanced rate of bone maturation. Mean 24-h estradiol levels correlated significantly with chronological age and bone age as well as with insulin-like growth factor I, insulin-like growth factor-binding protein-3, dehydroepiandrosterone sulfate, mean 24-h GH, and lean body mass. Mean 24-h estradiol levels did not differ between obese and nonobese children [1.65+/-1.47 us. 2.75+/-3.30 pmol/L (0.45+/-0.40 vs. 0.75+/-0.90 pg/mL), respectively]. Similar mean 24-h estradiol levels in obese and nonobese children are consistent with the increased bone maturation of the obese children. Estradiol did not correlate significantly with DEXA fat mass, body mass index, or arm fat measures of adiposity. Obese children had higher 24-h mean leptin concentrations than nonobese children (28.6+/-17.4 vs. 6.8+/-7.1 ng/mL; P < 0.001). Leptin concentrations positively correlated with DEXA fat mass, body mass index, and arm fat measurement of adiposity. Girls had higher 24-h mean leptin levels than boys when controlling for adiposity. Estradiol and leptin concentrations fluctuated over a 24-h period in both groups, with all children having higher leptin concentrations at night and higher estradiol concentrations in the morning. This diurnal rhythm was of a similar pattern, but at higher levels for leptin and lower levels for estradiol in the obese children compared to nonobese children. There was no significant correlation between estradiol and leptin levels. Bone mineral density, as measured by DEXA, did not differ between obese and nonobese children. Similar bone mineral density values in obese and nonobese children are consistent with the increased bone maturation of the obese children. Bone mineral density was not correlated with estradiol or leptin level in these children. In conclusion, obese children had similar estradiol levels and equivalent bone ages at a younger chronological age than nonobese children. Leptin was higher in these obese children, but did not correlate with estradiol level or bone age. These findings suggest that the role of leptin in both obesity and pubertal development is not directly correlated with the estradiol level.