Predictive value of digital rectal examination for prostate cancer detection is modified by obesity

Obesity and prostate cancer screening, incidence, and mortality in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial

BACKGROUND

Though obesity, measured by body mass index (BMI), is an established risk factor for several cancer sites, there is conflicting evidence on whether obesity increases prostate cancer risk or mortality and, if it does, whether it increases risk directly or indirectly by affecting prostate cancer screening efficacy.

METHODS

We examined associations between BMI and prostate cancer screening outcomes, incidence, and mortality in men randomly assigned to the intervention arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (n = 36 756) between 1993 and 2001. Participants received annual screening with the prostate-specific antigen test and digital rectal exam. Associations between baseline BMI and screening outcomes were assessed via multinomial logistic regression, and associations with prostate cancer incidence and mortality were assessed via Cox proportional hazards regression.

RESULTS

Individuals with higher BMI were less likely to screen positive via the prostate-specific antigen test and/or digital rectal exam and more likely to have an inadequate screen (all Ptrend < .01). Higher BMI was inversely associated with prostate cancer incidence (per 5 kg/m2 BMI increase: hazard ratio [HR] = 0.94, 95% confidence interval [CI] = 0.91 to 0.97), including incidence of early stage (HR = 0.94, 95% CI = 0.90 to 0.97) and advanced-stage (HR = 0.91, 95% CI = 0.82 to 1.02) disease, but positively associated with prostate cancer mortality (HR = 1.21, 95% CI = 1.06 to 1.37). The association with mortality was not modified by screening outcome (Pinteraction = .13).

CONCLUSIONS

Within this screened population, individuals with higher BMI had lower risk of prostate cancer diagnosis but higher risk of prostate cancer mortality. As higher BMI was not positively associated with advanced-stage prostate cancer risk, the increased mortality is unlikely to be due to delayed prostate cancer detection.

Are associations between obesity and prostate cancer outcomes following radical prostatectomy the same in smokers and non-smokers? Results from the SEARCH Cohort

PURPOSE

Obesity and smoking have been associated with poor prostate cancer (PC) outcomes. We investigated associations between obesity and biochemical recurrence (BCR), metastasis, castrate resistant-PC (CRPC), PC-specific mortality (PCSM), and all-cause mortality (ACM) and examined if smoking modified these associations.

METHODS

We analyzed SEARCH Cohort data from men undergoing RP between 1990 and 2020. Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between body mass index (BMI) as a continuous variable and weight status classifications (normal: 18.5 ≤ 25 kg/m2; overweight: 25-29.9 kg/m2; obese: ≥ 30 kg/m2) and PC outcomes.

RESULTS

Among 6,241 men, 1,326 (21%) were normal weight, 2,756 (44%) overweight and 2159 (35%) obese; 1,841 (30%) were never-smokers, 2,768 (44%) former and 1,632 (26%) current-smokers. Among all men, obesity was associated with non-significant increased risk of PCSM, adj-HR = 1.71; 0.98-2.98, P = 0.057, while overweight and obesity were inversely associated with ACM, adj-HR = 0.75; 0.66-0.84, P < 0.001 and adj-HR = 0.86; 0.75-0.99, P = 0.033, respectively. Other associations were null. BCR and ACM were stratified for smoking status given evidence for interactions (P = 0.048 and P = 0.054, respectively). Among current-smokers, overweight was associated with an increase in BCR (adj-HR = 1.30; 1.07-1.60, P = 0.011) and a decrease in ACM (adj-HR = 0.70; 0.58-0.84, P < 0.001). Among never-smokers, BMI (continuous) was associated with an increase in ACM (adj-HR = 1.03; 1.00-1.06, P = 0.033).

CONCLUSIONS

While our results are consistent with obesity as a risk factor for PCSM, we present evidence of effect modification by smoking for BCR and ACM highlighting the importance of stratifying by smoking status to better understand associations with body weight.

Deep Learning Network for Segmentation of the Prostate Gland With Median Lobe Enlargement in T2-weighted MR Images: Comparison With Manual Segmentation Method

PURPOSE

Aim of this study was to evaluate a fully automated deep learning network named Efficient Neural Network (ENet) for segmentation of prostate gland with median lobe enlargement compared to manual segmentation.

MATERIALS AND METHODS

One-hundred-three patients with median lobe enlargement on prostate MRI were retrospectively included. Ellipsoid formula, manual segmentation and automatic segmentation were used for prostate volume estimation using T2 weighted MRI images. ENet was used for automatic segmentation; it is a deep learning network developed for fast inference and high accuracy in augmented reality and automotive scenarios. Student t-test was performed to compare prostate volumes obtained with ellipsoid formula, manual segmentation, and automated segmentation. To provide an evaluation of the similarity or difference to manual segmentation, sensitivity, positive predictive value (PPV), dice similarity coefficient (DSC), volume overlap error (VOE), and volumetric difference (VD) were calculated.

RESULTS

Differences between prostate volume obtained from ellipsoid formula versus manual segmentation and versus automatic segmentation were statistically significant (P < 0.049318 and P < 0.034305, respectively), while no statistical difference was found between volume obtained from manual versus automatic segmentation (P = 0.438045). The performance of ENet versus manual segmentations was good providing a sensitivity of 93.51%, a PPV of 87.93%, a DSC of 90.38%, a VOE of 17.32% and a VD of 6.85%.

CONCLUSION

The presence of median lobe enlargement may lead to MRI volume overestimation when using the ellipsoid formula so that a segmentation method is recommended. ENet volume estimation showed great accuracy in evaluation of prostate volume similar to that of manual segmentation.

Impact of Body Mass Index on the Accuracy of Physical Examination and MRI of the Shoulder

BACKGROUND

The physical examination of overweight patients can require specific adaptations. Orthopaedic literature on the impact of body mass index (BMI) on the physical examination of the shoulder is virtually nonexistent.

PURPOSE

To assess whether BMI affects the sensitivity and specificity of common shoulder tests, using arthroscopy as a gold standard. We also examined the effects of BMI on the sensitivity and specificity of magnetic resonance imaging (MRI) of the shoulder for reference.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

We analyzed the data of 116 consecutive patients who underwent shoulder arthroscopy for the treatment of rotator cuff tears, Bankart lesions, and superior labral anterior-posterior (SLAP) lesions. Preoperative BMI, physical examination of the shoulder findings, and MRI findings were extracted. Contingency tables and receiver operating characteristic curves were used to evaluate the sensitivity and specificity of provocative tests of the shoulder and MRI as well as their relationship to BMI.

RESULTS

The sensitivity and specificity of the Jobe supraspinatus test were 77.8% and 72.7% in patients with BMI ≤25, 82.6% and 70.6% in those with 25 < BMI ≤ 30, and 81.3% and 55.6% in those with BMI >30, respectively (P < .001). The apprehension and relocation tests demonstrated higher sensitivity and specificity for the overweight patients (25 < BMI ≤ 30) compared with the other BMI groups, with a sensitivity and specificity of 83.3% and 100% for the apprehension test and a sensitivity and specificity of 75% and 100% for the relocation test, respectively. The O'Brien, Speed, and Ebinger tests for SLAP tears had low accuracy and did not yield statistically significant results. MRI interpretation was found to be influenced by BMI in obese patients, especially when SLAP lesions were assessed.

CONCLUSION

Counterintuitively, tests for shoulder instability had greater specificity in overweight patients and should be encouraged, particularly in obese patients, in whom the specificity of shoulder MRI for the detection of a Bankart lesion is lower. The Jobe test was more sensitive but less specific in overweight patients. These findings may assist care providers in improving the interpretation of the shoulder examination of overweight patients and consequently lead to better treatment-related decisions.

Does increased body mass index lead to elevated prostate cancer risk? It depends on waist circumference

Background

We examined the association between obesity and prostate cancer based on both body mass index (BMI) and waist circumference (WC) using the National Health Insurance System (NHIS) database for the entire male population of Korea.

Methods

A total of 1,917,430 men who underwent at least one health examination in 2009 without a previous diagnosis of any other cancer were tracked through December 2015. The hazard ratio (HR) and 95% confidence interval (CI) value for the association between prostate cancer and obesity were analyzed using multiple Cox regression model. Since there was a statistically significant interaction between WC and BMI, a multiple HR for prostate cancer was estimated with stratifying both WC and BMI to control the interaction between WC and BMI.

Results

Without considering WC as an adjustment factor, very weak association between BMI and prostate cancer development risk was observed. When WC was considered as an adjustment factor, no significant change in the HRs for prostate cancer development beyond the reference BMI was observed in the group with WC < 85 cm in the multivariable-adjusted models. However, in the group with WC ≥ 85 cm, the HRs for prostate cancer increased as the BMI increased beyond the reference BMI. In addition, there was a discrepancy in the trend of prostate cancer development according to BMI among the groups with different categories for WC.

Conclusion

In groups with abdominal obesity, a significant linear relationship was observed between increasing BMI and prostate cancer risk. Higher the WC category, the stronger was the association with BMI, signifying that the association of BMI with risk of prostate cancer development depends on abdominal obesity.

Obesity suppresses tumor attributable PSA, affecting risk categorization

Obesity is linked with more aggressive prostate cancer and higher rates of disease recurrence post treatment. It is unclear if this is due to specific tumor-promoting effects of obesity or diagnostic bias. Patients undergoing prostatectomy were categorized according to their body mass index (BMI). Expected prostate-specific antigen (PSA) levels were calculated for each patient based on tumor characteristics. The effect of obesity on the accuracy of pre-treatment risk categorization was determined, and mediation analysis was used to identify the contribution of biologic vs non-biologic mechanisms to the observed increased risk of biochemical recurrence. Residual tumor-promoting effects were estimated in a survival model controlling for diagnostic error. The following results were obtained. The analysis included 1587 patients. Despite similar rates of adverse pathological features at prostatectomy, biochemical recurrence rates were significantly higher in very obese patients, which persisted after adjustment for stage, grade and PSA. Tumor volume however correlated significantly with BMI (P = 0.004), and the difference in predicted and observed 'tumor-attributable' PSA (Delta-PSA) in very obese patients was greater than three times higher than that of healthy patients (P = 0.0067). Regression analysis indicated that the effect of BMI on tumor volume was fully mediated indirectly by its effect on PSA. Inclusion of this diagnostic error as a covariate in the survival analysis attenuated the effect of BMI on recurrence. In conclusion, being very obese suppresses tumor-associated PSA resulting in a diagnostic bias that is responsible for errors in risk classification, and potentially contributes to a delay in initial presentation.

Correlation between body mass index (BMI) and the Gleason score of prostate biopsies in Chinese population

We assessed the correlation between BMI and Gleason score in prostate biopsies in Chinese Population. In this retrospective study, we collected the Gleason score, PSA, BMI, age, race, and other related clinical data on 290 patients who had undergone prostatic biopsy. We then compared the prostate cancer detection rates and Gleason scores between the high BMI group (BMI ≥ 25; 143 cases) and low BMI group (< 25; 147 cases). Among the 137 patients in whom prostate cancer detected, 70 had high BMIs and 67 had normal BMIs, making the detection rates 48.95% and 45.58% respectively. Seventeen prostate cancer patients had low Gleason scores (Gleason score < 7), while 120 had high Gleason scores (≥ 7). Within the high BMI group, 44.76% had high Gleason scores, which was significantly greater than the 38.10% in the low BMI group (P = 0.027). These results indicate that while there was no effect of BMI on the rate of positive prostate cancer biopsies, the rate of high Gleason scores was greater in the high BMI group than the normal BMI group.

Does obesity modify prostate cancer detection in a European cohort?

INTRODUCTION

To investigate prostate-specific antigen (PSA) accuracy and digital rectal examination (DRE) accuracy in detecting prostate cancer according to body mass index (BMI) in Spanish men with an indication of the first prostate biopsy.

MATERIAL AND METHODS

We reviewed the clinical and histopathological data of 1,319 patients who underwent transrectal ultrasound-guided prostate needle biopsy. The patients were categorised according to the BMI as follows: <25 kg/m² (normal weight); 25-29.9 kg/m² (overweight); and ≥30 kg/m² (obese). Receiver operator characteristic curves were used to assess PSA accuracy and DRE accuracy by calculating the area under the curve.

RESULTS

The obesity rate of the cohort was 14%. PSA accuracy for predicting prostate cancer in each BMI category was 0.52, 0.58 and 0.62, respectively (p = 0.01). After stratification by DRE findings, there was no difference in the performance accuracy of PSA in predicting the presence of cancer across BMI groups in abnormal DRE (p = 0.90). Serum PSA, DRE and BMI were strong predictors of prostate cancer diagnosis (odds ratio 1.07, 2.02 and 1.4, respectively; p <0.001). When the DRE was abnormal, a BMI ≥30 increased the risk of prostate cancer twice. With the addition of BMI to the model, the area under the curve of the combined PSA and DRE for diagnosing prostate cancer improved from 0.60 to 0.63.

CONCLUSIONS

The predictive value of PSA in predicting prostate cancer is not poorer in the obese population and the predictive value of an abnormal DRE in cancer detection is significantly modified by the patient's BMI.

Association of Obesity-Related Hemodilution of Prostate-Specific Antigen, Dihydrotestosterone, and Testosterone

BACKGROUND

Prostate-specific antigen (PSA) hemodilution is the leading theory for lower PSA values in obese men. However, testosterone and dihydrotestosterone (DHT), which are necessary for PSA production, are reduced in obese men. We assessed the relationship of body mass index (BMI) and PSA, taking into consideration the effect of testosterone and DHT.

METHODS

Among 8,122 participants in Reduction by Dutasteride of Prostate Cancer Events (REDUCE), complete data were available for 7,275. BMI was categorized as normal (<25 kg/m² ), overweight (25-29.9 kg/m² ), obese (30-34.9 kg/m² ), or moderate + severely obese (≥35 kg/m² ). Associations between BMI, testosterone, and DHT and the outcome variable of PSA were examined using linear regression.

RESULTS

There were 1,964 (27.0%) normal weight, 3,826 (52.6%) overweight, 1,200 (16.5%) obese, and 285 (3.9%) moderately + severely obese patients. With increasing BMI, there was a progressive decrease in PSA (P = 0.02), increase in prostate volume (P < 0.001), and decrease in both testosterone (P < 0.001) and DHT (P < 0.001). Using linear regression, increasing BMI was associated with decreasing serum PSA values. Furthermore, BMI remained inversely associated with PSA after individually adjusting for testosterone and DHT, as well as when adjusting for testosterone and DHT in the same model. Decreased androgen levels accounted for only 19% of the lower PSA in men with higher BMI.

CONCLUSIONS

Only a fraction of lower PSA in obese men could be attributed to testosterone and DHT levels. The remaining factors explaining lower PSA are unaccounted for, presumably secondary to hemodilution associated with increased plasma volume in obese men. Prostate 77:466-470, 2017. © 2016 Wiley Periodicals, Inc.

Obesity and prostate cancer-specific mortality after radical prostatectomy: results from the Shared Equal Access Regional Cancer Hospital (SEARCH) database

Background:

At the population level, obesity is associated with prostate cancer (PC) mortality. However, few studies analyzed the associations between obesity and long-term PC-specific outcomes after initial treatment.

Methods:

We conducted a retrospective analysis of 4268 radical prostatectomy patients within the Shared Equal Access Regional Cancer Hospital (SEARCH) database. Cox models accounting for known risk factors were used to examine the associations between body mass index (BMI) and PC-specific mortality (PCSM; primary outcome). Secondary outcomes included biochemical recurrence (BCR) and castration-resistant PC (CRPC). BMI was used as a continuous and categorical variable (normal <25 kg/m², overweight 25–29.9 kg/m² and obese ⩾30 kg/m²). Median follow-up among all men who were alive at last follow-up was 6.8 years (interquartile range=3.5–11.0). During this time, 1384 men developed BCR, 117 developed CRPC and 84 died from PC. Hazard ratios were analyzed using competing-risks regression analysis accounting for non-PC death as a competing risk.

Results:

On crude analysis, higher BMI was not associated with risk of PCSM (P=0.112), BCR (0.259) and CRPC (P=0.277). However, when BMI was categorized, overweight (hazard ratio (HR) 1.99, P=0.034) and obesity (HR 1.97, P=0.048) were significantly associated with PCSM. Obesity and overweight were not associated with BCR or CRPC (all P⩾0.189). On multivariable analysis adjusting for both clinical and pathological features, results were little changed in that obesity (HR=2.05, P=0.039) and overweight (HR=1.88, P=0.061) were associated with higher risk of PCSM, but not with BCR or CRPC (all P⩾0.114) with the exception that the association for overweight was no longer statistical significant.

Conclusions:

Overweight and obesity were associated with increased risk of PCSM after radical prostatectomy. If validated in larger studies with longer follow-up, obesity may be established as a potentially modifiable risk factor for PCSM.

The clinical effectiveness and cost-effectiveness of the PROGENSA® prostate cancer antigen 3 assay and the Prostate Health Index in the diagnosis of prostate cancer: a systematic review and economic evaluation

BACKGROUND

There is no single definitive test to identify prostate cancer in men. Biopsies are commonly used to obtain samples of prostate tissue for histopathological examination. However, this approach frequently misses cases of cancer, meaning that repeat biopsies may be necessary to obtain a diagnosis. The PROGENSA(®) prostate cancer antigen 3 (PCA3) assay (Hologic Gen-Probe, Marlborough, MA, USA) and the Prostate Health Index (phi; Beckman Coulter Inc., Brea, CA, USA) are two new tests (a urine test and a blood test, respectively) that are designed to be used to help clinicians decide whether or not to recommend a repeat biopsy.

OBJECTIVE

To evaluate the clinical effectiveness and cost-effectiveness of the PCA3 assay and the phi in the diagnosis of prostate cancer.

DATA SOURCES

Multiple publication databases and trial registers were searched in May 2014 (from 2000 to May 2014), including MEDLINE, EMBASE, The Cochrane Library, ISI Web of Science, Medion, Aggressive Research Intelligence Facility database, ClinicalTrials.gov, International Standard Randomised Controlled Trial Number Register and World Health Organization International Clinical Trials Registry Platform.

REVIEW METHODS

The assessment of clinical effectiveness involved three separate systematic reviews, namely reviews of the analytical validity, the clinical validity of these tests and the clinical utility of these tests. The assessment of cost-effectiveness comprised a systematic review of full economic evaluations and the development of a de novo economic model.

SETTING

The perspective of the evaluation was the NHS in England and Wales.

PARTICIPANTS

Men suspected of having prostate cancer for whom the results of an initial prostate biopsy were negative or equivocal.

INTERVENTIONS

The use of the PCA3 score or phi in combination with existing tests (including histopathology results, prostate-specific antigen level and digital rectal examination), multiparametric magnetic resonance imaging and clinical judgement.

RESULTS

In addition to documents published by the manufacturers, six studies were identified for inclusion in the analytical validity review. The review identified issues concerning the precision of the PCA3 assay measurements. It also highlighted issues relating to the storage requirements and stability of samples intended for analysis using the phi assay. Fifteen studies met the inclusion criteria for the clinical validity review. These studies reported results for 10 different clinical comparisons. There was insufficient evidence to enable the identification of appropriate test threshold values for use in a clinical setting. In addition, the implications of adding either the PCA3 assay or the phi to clinical assessment were not clear. Furthermore, the addition of the PCA3 assay or the phi to clinical assessment plus magnetic resonance imaging was not found to improve discrimination. No published papers met the inclusion criteria for either the clinical utility review or the cost-effectiveness review. The results from the cost-effectiveness analyses indicated that using either the PCA3 assay or the phi in the NHS was not cost-effective.

LIMITATIONS

The main limitations of the systematic review of clinical validity are that the review conclusions are over-reliant on findings from one study, the descriptions of clinical assessment vary widely within reviewed studies and many of the reported results for the clinical validity outcomes do not include either standard errors or confidence intervals.

CONCLUSIONS

The clinical benefit of using the PCA3 assay or the phi in combination with existing tests, scans and clinical judgement has not yet been confirmed. The results from the cost-effectiveness analyses indicate that the use of these tests in the NHS would not be cost-effective.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014009595.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Obesity and hypogonadism are associated with an increased risk of predominant Gleason 4 pattern on radical prostatectomy specimen

PURPOSE

To compare histological features of prostate cancer according to both obesity, defined by a body mass index (BMI) ≥30 kg/m2, and androgenic status in patients who underwent radical prostatectomy.

MATERIALS AND METHODS

Between March 2007 and September 2013, clinical, pathological and biological data were prospectively collected for patients referred for radical prostatectomy in a single European center. Preoperative total testosterone (TT) and bioavailable testosterone (bioT) serum determinations were performed. The threshold for hypogonadism was set at TT <3 ng/mL. The preoperative PSA value was registered. Gleason score (GS) and predominant Gleason pattern (PrdGP) were determined in prostate tissue specimens, and crosschecked by two uro-pathologists. Statistical analyzes were done for PrdGP4 risk assessment.

RESULTS

A total of 937 consecutive patients were included. One hundred and thirty-five filled the criterion for obesity (14.4%), out of which 42 had TT <3 ng/mL (31.1%), while in non-obese patients, only 97 had TT <3 ng/mL (12.0%). In prostate specimens, mean GS was 6.8±0.5: 291 patients (31.1%) had a PrdGP4. The incidence of PrdGP4 was higher (p<0.001) in the 135 obese patients [50% when hypogonadal (p<0.02) or 42% when eugonadal (p<0.005)] than in non-obese patients (28.9% and 27.1%, respectively). In multivariable analyzis for PrdGP4 risk, obesity, TT <3 ng/mL, PSA, and age were independent risk factors.

CONCLUSIONS

Both obesity and hypogonadism are independent risk factors for PrdGP4 in patients who underwent radical prostatectomy and should be taken into account in localized prostate cancer management, to improve the therapeutic choice, especially when prostate sparing approach is considered.

Obesity and cancer: mechanistic insights from transdisciplinary studies

Obesity is associated with a range of health outcomes that are of clinical and public health significance, including cancer. Herein, we summarize epidemiologic and preclinical evidence for an association between obesity and increased risk of breast and prostate cancer incidence and mortality. Moreover, we describe data from observational studies of weight change in humans and from calorie-restriction studies in mouse models that support a potential role for weight loss in counteracting tumor-promoting properties of obesity in breast and prostate cancers. Given that weight loss is challenging to achieve and maintain, we also consider evidence linking treatments for obesity-associated co-morbidities, including metformin, statins and non-steroidal anti-inflammatory drugs, with reduced breast and prostate cancer incidence and mortality. Finally, we highlight several challenges that should be considered when conducting epidemiologic and preclinical research in the area of obesity and cancer, including the measurement of obesity in population-based studies, the timing of obesity and weight change in relation to tumor latency and cancer diagnosis, and the heterogeneous nature of obesity and its associated co-morbidities. Given that obesity is a complex trait, comprised of behavioral, epidemiologic and molecular/metabolic factors, we argue that a transdisciplinary approach is the key to understanding the mechanisms linking obesity and cancer. As such, this review highlights the critical need to integrate evidence from both epidemiologic and preclinical studies to gain insight into both biologic and non-biologic mechanisms contributing to the obesity-cancer link.

Metabolic syndrome and prostate cancer risk in a population-based case-control study in Montreal, Canada

Background

The role of metabolic syndrome (MetS) in prostate cancer risk is still debated. We investigated it in a large population-based case–control study.

Methods

Cases were 1937 men with incident prostate cancer, aged ≤75 years, diagnosed across French hospitals in the Montreal area between 2005 and 2009. Concurrently, 1995 population controls from the same residential area and age distribution were randomly selected from electoral list of French-speaking men. Detailed lifestyle and medical histories, and anthropometric measures, were collected during in-person interviews. Prevalence of MetS components (type 2 diabetes, high blood pressure, dyslipidemia and abdominal obesity) was estimated at 2 years before diagnosis for cases/ interview for controls, and at ages 20, 40, 50 and 60. Logistic regression was used to estimate odds ratios (OR) and 95 % confidence intervals for the association between MetS and prostate cancer risk.

Results

A history of MetS (≥3 components vs <3) was associated with a reduced risk of prostate cancer (OR = 0.70 [0.60, 0.82]) after considering potential confounders. The negative association was particularly pronounced with a young age (≤40 years) at MetS onset (OR = 0.38 [0.16-0.89]), did not vary according to prostate cancer aggressiveness, and was only partly explained by the presence of type 2 diabetes. A risk decrease was observed with the number of MetS components, suggesting a synergistic interaction of the components.

Discussion

The observed negative association, consistent with results from other North American populations undergoing regular prostate cancer screening, underlines the importance of considering PSA-testing when studying the MetS-prostate cancer association.

Conclusions

Findings from this study are consistent with an inverse association between MetS and prostate cancer risk.

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

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

Prostate cancer incidence, clinical stage and survival in relation to obesity: a prospective cohort study in Denmark

There is no clear link between obesity and prostate cancer incidence but an association has been reported between obesity and fatal prostate cancer. We report on two prospective cohort analyses on (i) the incidence of prostate cancer in relation to obesity in a cohort of men with no previous cancer, and on (ii) the stage distribution and prostate cancer specific mortality in relation to obesity among men with prostate cancer. The "Diet, Cancer and Health" prospective cohort study was established in Denmark in 1993-1997 and accrued 26,944 men aged 50-64 years. Data were extracted on height, weight, body mass index (BMI), waist circumference and body fat percentage. Information on cancer incidence and deaths were obtained by record linkage with the Danish Cancer Register and the Danish Death Register. The incidence rate of prostate cancer was similar or slightly lower in obese men compared with nonobese men, but obese men tended to be diagnosed with more advanced prostate cancer. The proportion of Stage 3-4 cancers was 37% in the lowest BMI quartile and 48% in the highest (p = 0.006). Obese men with prostate cancer had higher prostate cancer specific mortality. The hazard ratio comparing the highest and the lowest quartiles of BMI was 1.48 (95% confidence interval: 1.06-2.05; p-value for trend: 0.002). The association was attenuated but not eliminated by statistical adjustment for stage, and the data are suggestive of a stage-independent causal pathway where prostate cancer in obese men has higher fatality, even in early-stage disease.

Ethnicity is an independent determinant of age-specific PSA level: findings from a multiethnic Asian setting

Objectives

To study the baseline PSA profile and determine the factors influencing the PSA levels within a multiethnic Asian setting.

Materials and Methods

We conducted a cross-sectional study of 1054 men with no clinical evidence of prostate cancer, prostate surgery or 5α-reductase inhibitor treatment of known prostate conditions. The serum PSA concentration of each subject was assayed. Potential factors associated with PSA level including age, ethnicity, height, weight, family history of prostate cancer, lower urinary tract voiding symptoms (LUTS), prostate volume and digital rectal examination (DRE) were evaluated using univariable and multivariable analysis.

Results

There were 38 men (3.6%) found to have a PSA level above 4 ng/ml and 1016 (96.4%) with a healthy PSA (≤4 ng/ml). The median PSA level of Malay, Chinese and Indian men was 1.00 ng/ml, 1.16 ng/ml and 0.83 ng/ml, respectively. Indians had a relatively lower median PSA level and prostate volume than Malays and Chinese, who shared a comparable median PSA value across all 10-years age groups. The PSA density was fairly similar amongst all ethnicities. Further analysis showed that ethnicity, weight and prostate volume were independent factors associated with age specific PSA level in the multivariable analysis (p<0.05).

Conclusion

These findings support the concept that the baseline PSA level varies between different ethnicities across all age groups. In addition to age and prostate volume, ethnicity may also need to be taken into account when investigating serum PSA concentrations in the multiethnic Asian population.

Is there a role for body mass index in the assessment of prostate cancer risk on biopsy?

PURPOSE

We examine the role of body mass index in the assessment of prostate cancer risk.

MATERIALS AND METHODS

A total of 3,258 participants who underwent biopsy (including 1,902 men with a diagnosis of prostate cancer) were identified from the Selenium and Vitamin E Cancer Prevention Trial. The associations of body mass index with prostate cancer and high grade prostate cancer were examined using logistic regression, adjusting for age, race, body mass index adjusted prostate specific antigen, digital rectal examination, family history of prostate cancer, biopsy history, prostate specific antigen velocity, and time between study entry and the last biopsy. The prediction models were compared with our previously developed body mass index adjusted Prostate Cancer Prevention Trial prostate cancer risk calculator.

RESULTS

Of the study subjects 49.1% were overweight and 29.3% were obese. After adjustment, among men without a known family history of prostate cancer, increased body mass index was not associated with a higher risk of prostate cancer (per one-unit increase in logBMI OR 0.83, p=0.54) but was significantly associated with a higher risk of high grade prostate cancer (ie Gleason score 7 or greater prostate cancer) (OR 2.31, p=0.03). For men with a known family history of prostate cancer the risks of prostate cancer and high grade prostate cancer increased rapidly as body mass index increased (prostate cancer OR 3.73, p=0.02; high grade prostate cancer OR 7.95, p=0.002). The previously developed risk calculator generally underestimated the risks of prostate cancer and high grade prostate cancer.

CONCLUSIONS

Body mass index provided independently predictive information regarding the risks of prostate cancer and high grade prostate cancer after adjusting for other risk factors. Body mass index, especially in men with a known family history of prostate cancer, should be considered for inclusion in any clinical assessment of prostate cancer risk and recommendations regarding prostate biopsy.

Screening for prostate cancer: are digital rectal examinations being performed?

OBJECTIVE

Prostate cancer is common and prostate cancer screening is controversial; this retrospective observational study was conducted to determine the prevalence of digital rectal examination (DRE) in those in whom a prostate-specific antigen (PSA) test was performed.

METHODS

A manual review was performed of the electronic medical record for male veterans in the VA Connecticut Healthcare System without a history of known prostate cancer aged between 50 and 74 years who underwent PSA testing.

MAIN OUTCOMES

Documentation of DRE (or refusal) within 12 months before or after the performance of a PSA test.

RESULTS

Less than half (47.6%) of patients underwent DRE. An additional 6.9% were offered DRE and refused. Although the provider gender was not associated with DRE, resident physicians were less likely to perform DRE than nonresidents; P = 0.01. Patients whose PSA was > 4.0 ng/mL were more likely to undergo DRE than those whose PSA was ≤ 4.0 ng/mL; P = 0.002. Those with body mass index (BMI) > 40 kg/m 2 were less likely to undergo DRE than those with BMI < 30 kg/m 2 ; P = 0.04.

CONCLUSIONS

Screening for prostate cancer remains controversial. We found a low rate of DRE among veterans in whom prostate cancer screening was entertained. Although the provider gender does not seem to influence DRE, resident physicians were less likely to perform DRE than other providers. Our finding that BMI > 40 kg/m 2 is associated with a lower rate of DRE than those with BMI < 30 kg/m 2 is consistent with screening for other cancers and should be explored further.

Left lobe of the prostate during clinical prostate cancer screening: the dark side of the gland for right-handed examiners

BACKGROUND

The predictive value of the abnormality side during digital rectal examination (DRE) has never been studied, suggesting that physicians examined the left lobe of the gland as well as the right lobe. We aimed to assess the predictive value of the side of DRE abnormality for prostate cancer (PCa) detection and aggressiveness in right-handed urologists.

METHODS

An analysis of a prospective database was carried out that included all consecutive men undergoing prostate biopsies between 2001 and 2012. The main end point was the predictive value of the abnormality side during DRE for cancer detection in clinically suspicious unilateral T2 disease. The diagnostic performance of left- versus right-sided abnormality was also assessed in terms of sensitivity, specificity and negative/positive predictive values.

RESULTS

Overall, 308 patients had a suspicious unilateral clinical disease (detection rate 57.5%). The cancer detection rate was significantly higher in case of left-sided compared with right-sided clinical T2 stage (odds ratio 2.1). In case of left-sided disease, the number of positive cores, the rate of perineural invasion, the rate of primary grade 4 pattern and the percentage of cancer involvement per core were significantly higher compared with those reported for right-sided disease. The predictive value of abnormality laterality for cancer detection and aggressiveness remained statistically independent in multivariate models. The positive predictive value for cancer detection was 64.6 in case of suspicious left-sided disease versus 46.9 in case of right-sided disease.

CONCLUSIONS

The risks of detecting PCa and aggressive disease on biopsy are significantly higher when DRE reveals a suspicious left-sided clinical disease as compared with right-sided disease. Right-handed physicians should be aware of this variance in diagnostic performance and potential underdetection of left-sided clinical disease, and should improve their examination of the left lobe of the gland by conducting longer exams or changing the patient's position.

Lifestyle and dietary factors in prostate cancer prevention

The etiology of prostate cancer (PCa) is still largely unknown and the only well-established risk factors are those that are non-modifiable (age, race, and family history). Therefore, the identification of lifestyle and dietary factors which might prevent PCa development and progression is of paramount importance from a public health point of view. Accumulating evidence indicates that obesity may have a dual effect on PCa: an increased risk of aggressive PCa and a decreased risk of localized PCa. Both occupational and leisure time physical activity have been observed to be associated with a reduced PCa risk. Different dietary factors including coffee have been examined in several epidemiological studies, but results have been mostly inconsistent. However, these inconsistencies can be, at least partly, explained by the fact that the majority of those studies examined total PCa risk only and, in addition, they did not take into account the different genetic characteristics within the study populations. Therefore, the future epidemiological studies should focus on the analysis of PCa subtypes separately in order to examine possible etiological heterogeneity of PCa in relation to some exposures. In addition, differences in the genetic characteristics of the study participants should be taken into account to explore the possibility of gene-environment interactions.

Obesity and prostate cancer: weighing the evidence

CONTEXT

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

OBJECTIVE

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

EVIDENCE ACQUISITION

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

EVIDENCE SYNTHESIS

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

CONCLUSIONS

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

Prostate cancer risk in men with baseline history of coronary artery disease: results from the REDUCE Study

BACKGROUND

Coronary artery disease (CAD) and prostate cancer (PCa) are not only common diseases, but share many risk factors. To date, only a few studies have explored the relationship between CAD and PCa risk, with conflicting results.

METHODS

The four-year REDUCE study tested dutasteride 0.5 mg daily for PCa risk reduction in men with prostate specific antigen (PSA) of 2.5 to 10.0 ng/mL and a negative biopsy. Among men who underwent at least one on-study biopsy (n = 6,729; 82.8%), the association between CAD and overall PCa risk and disease grade was examined with logistic and multinomial logistic regression adjusting for clinicopathologic features, respectively.

RESULTS

Overall, 547 men (8.6%) had a history of CAD. Men with CAD were significantly older and had higher body mass index, PSA, and larger prostate volumes and were more likely to have diabetes, hypertension, and hypercholesterolemia and take aspirin and statins. On multivariate analysis, CAD was associated with a 35% increased risk of PCa diagnosis (OR = 1.35, 95% CI: 1.08-1.67, P = 0.007), while elevating risk of both low- (OR = 1.34, 95% CI: 1.05-1.73, P = 0.02) and high-grade disease (OR = 1.34, 95% CI: 0.95-1.88, P = 0.09).

CONCLUSIONS

In a post hoc hypothesis developing secondary analysis of the REDUCE study, CAD was significantly associated with increased PCa diagnosis.

IMPACT

If confirmed in other studies, this suggests CAD may be a novel PCa risk factor and suggests common shared etiologies. Whether lifestyle changes shown to reduce CAD risk (i.e., weight loss, exercise, cholesterol reduction, etc.) can reduce PCa risk, warrants further study.