The impact of obesity on the predictive accuracy of PSA in men undergoing prostate biopsy

Impact of obesity on perioperative, functional and oncological outcomes after robotic-assisted radical prostatectomy in a high-volume center

OBJECTIVE

To compare surgical, oncological and functional outcomes between obese vs. normal-weight prostate cancer (PCa) patients treated with robotic-assisted radical prostatectomy (RARP).

MATERIALS AND METHODS

We assessed 4555 consecutive RARP patients from a high-volume center 2008-2018. Analyses were restricted to normal-weight vs. obese patients (≥ 30 kg/m²). Multivariable cox regression analyses (MVA) assessed the effect of obesity on biochemical recurrence (BCR), metastatic progression (MP), erectile function and urinary continence recovery. Analyses were repeated after propensity score matching.

RESULTS

Before matching, higher rates of pathological Gleason Grade group ≥ 4 (14 vs. 18%; p = 0.004) and pT3 stage (33 vs. 35%; p = 0.016) were observed in obese patients, with similar observations for surgery time, blood loss and 30-day wound- and surgical complication rates. For normal-weight vs. obese patients, BCR- and MP-free rates were 86 vs. 85% (p = 0.97) and 97.5 vs.97.8% (p = 0.8) at 48 months. Similarly, rates of erectile function at 36 months and urinary continence at 12 months were 56 vs. 49% (p = 0.012) and 88 vs. 85% (p = 0.003), respectively. Before and after propensity score matching, obesity had no effect on BCR or MP, but a negative effect on erectile function (matched HR 0.87, 95%CI 0.76-0.99; p = 0.029) and urinary continence recovery (matched HR 0.91, 95%CI 0.84-0.98; p = 0.014).

CONCLUSIONS

Obesity did not represent a risk factor of BCR or MP after RARP despite higher rates of adverse pathological features. However, obesity was associated with higher risk of perioperative morbidity and impaired functional outcomes. Such information is integral for patient counselling. Thus, weight loss before RARP should be encouraged.

An overview of translational prostate cancer cohorts for prognostic and predictive studies

The aim of this review is to describe the characteristics of patient cohorts commonly used for translational biomarker research in prostate cancer and to outline the most prominent contemporary cohorts which serve as a source of prognostic and predictive biomarkers. A non-systematic review of the literature was performed to identify and summarise well-characterized translational prostate cancer cohorts that provide state-of-the-art characterization of (i) primary and (ii) metastatic and castration-resistant prostate cancer. The main advantages and features of these cohorts are a substantial number of patients, unique patient groups, comprehensive genetic characterisation of tumours using multi-omics/next-generation sequencing approaches, high-quality control standards and fully or partially open data for the research community. This overview includes the contemporary cohorts which serve as a rich source of new targets for prognostic and predictive biomarkers as well as a reference database for validation of known biomarkers, therefore representing the cohorts whose impact extends over the current state of biomarker research into the near future (5-10 years).

The inverse relationship between prostate specific antigen (PSA) and obesity

Obese men have lower serum prostate-specific antigen (PSA) than comparably aged lean men, but the underlying mechanism remains unclear. The aim of this study was to determine the effect of obesity on PSA and the potential contributing mechanisms. A cohort of 1195 men aged 35 years and over at recruitment, with demographic, anthropometric (BMI, waist circumference (WC)) and serum hormone (serum testosterone, estradiol (E2)) PSA and hematology assessments obtained over two waves was assessed. Men with a history of prostate cancer or missing PSA were excluded, leaving 970 men for the final analysis. Mixed-effects regressions and mediation analyses adjusting for hormonal and volumetric factors explore the potential mechanisms relating obesity to PSA. After adjusting for age, PSA levels were lower in men with greater WC (P = 0.001). In a multivariable model including WC, age, E2/testosterone and PlasV as predictors, no statistically significant associations were observed between with PSA and either WC (P = 0.36) or PlasV (P = 0.49), while strong associations were observed with both E2/testosterone (P < 0.001) and age (P < 0.001). In the mediation analyses with PlasV as the mediator, the average causal mediation effect (ACME) explained roughly 20% of the total effect of WC on PSA (P = 0.31), while when E2/testosterone is a mediator, the ACME explained roughly 50% of the effect (P < 0.001). Our findings indicate that lower PSA levels in obese men, as compared to normal weight men, can be explained both by hormonal changes (elevated E2/testosterone ratio) and hemodilution. Hormonal factors therefore represent a substantial but underappreciated mediating pathway.

Repeat prostate-specific antigen (PSA) test before prostate biopsy: a 20% decrease in PSA values is associated with a reduced risk of cancer and particularly of high-grade cancer

OBJECTIVES

To analyse the impact of repeating a prostate-specific antigen (PSA) level assessment on prostate biopsy decision in a cohort of men undergoing prostate biopsy.

PATIENTS AND METHODS

From 2015 onwards, we consecutively enrolled, at a single institution in Italy, men undergoing 12-core transrectal ultrasonography-guided prostate needle biopsy. Indication for prostate biopsy was a PSA level of ≥4 ng/mL. Demographic, clinical, and histopathological data were collected. The PSA level was tested at enrolment (PSA₁ ) and 4 weeks later on the day before biopsy (PSA₂ ). Variations in PSA level were defined as: stable PSA₂ within a 10% variation, stable PSA₂ within a 20% variation, PSA₂ decreased by ≥10%, PSA₂ decreased by ≥20%, PSA₂ increased by ≥10%, PSA₂ increased by ≥20%, and PSA₂ <4 ng/mL. Percentages and multinomial logistic regression were used to analyse biopsy outcomes. High-grade cancer was defined as Grade group ≥3.

RESULTS

Overall, 331 patients were enrolled. Prostate cancer was diagnosed in 153/331 (46%) patients and of them 80/153 (52%) had high-grade disease. When compared to the rest of the population, patients with a stable PSA within 20% variation had a higher risk of prostate cancer (odds ratio [OR] 1.80, P < 0.05) and high grade disease (OR 2.56, P < 0.05), patients with a PSA2 decreased by ≥20% had a lower risk of prostate cancer (OR 0.37, P < 0.05) and high grade disease (OR 0.13, P < 0.05), whilst patients with a PSA2 increased by ≥10% had an increased risk of high-grade prostate cancer (OR 1.93, P < 0.05). When PSA returned to normal values (<4 ng/mL) both risks of prostate cancer and high-grade disease were reduced (OR 0.33 and 0.01, respectively, P = 0.001).

CONCLUSION

In a cohort of Italian men undergoing prostate biopsy, a reduction of ≥20% in PSA levels significantly reduced the risk of high-grade prostate cancer. Further multicentre studies should validate our present results.

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.

Urinary melatonin-sulfate/cortisol ratio and the presence of prostate cancer: A case-control study

The circadian-related hormones, melatonin and cortisol, have oncostatic and immunosuppressive properties. This study examined the relationship between these two biomarkers and the presence of prostate cancer. We measured their major metabolites in urine collected from 120 newly diagnosed prostate cancer patients and 240 age-matched controls from January 2011 to April 2014. Compared with patients with lower urinary melatonin-sulfate or melatonin-sulfate/cortisol (MT/C) ratio levels, those with above-median levels were significantly less likely to have prostate cancer (adjusted OR (aOR) = 0.59, 95% CI = 0.35–0.99; aOR = 0.46, 95% CI: 0.27–0.77) or advanced stage prostate cancer (aOR = 0.49, 95% CI = 0.26–0.89; aOR = 0.33, 95% CI = 0.17–0.62). The combined effect of both low MT/C ratios and PSA levels exceeding 10 ng/ml was an 8.82-fold greater likelihood of prostate cancer and a 32.06-fold greater likelihood of advanced stage prostate cancer, compared to those with both high MT/C ratios and PSA levels less than 10 ng/ml. In conclusion, patients with high melatonin-sulfate levels or a high MT/C ratio were less likely to have prostate cancer or advanced stage prostate. Besides, a finding of a low MT/C ratio combined with a PSA level exceeding 10 ng/ml showed the greatest potential in detecting prostate cancer and advanced stage prostate cancer.

Effect of body mass index on the performance characteristics of PSA-related markers to detect prostate cancer

To examine whether the predictive performance of prostate-specific antigen (PSA) and PSA-related markers for prostate cancer (PCa) is modified by body mass index (BMI). Patients with a PSA 2-10 ng/mL who underwent multicore prostate biopsies were recruited from three tertiary centers. Serum markers measured included total PSA (tPSA), free-to-total PSA (f/tPSA), p2PSA, percentage of p2PSA (%p2PSA), and prostate health index (PHI). The association between serum markers and PCa risk was assessed by logistic regression. Predictive performance for each marker was quantified using the area under the receiver operator curves (AUC). Among 516 men, 18.2% had PCa at biopsy. For all tested markers, their predictive value on PCa risk was lower in obese patients compared to normal weight patients. We found statistically significant interactions between BMI and tPSA (P = 0.0026) and p2PSA (P = 0.038). PHI achieved an AUC of 0.872 in normal weight patients and 0.745 in obese patients, which outperformed the other predictors regardless of BMI category. In conclusion, PHI achieved the best predictive performance for detecting PCa and was not influenced by BMI.

Clinical performance of the Prostate Health Index (PHI) for the prediction of prostate cancer in obese men: data from the PROMEtheuS project, a multicentre European prospective study

OBJECTIVES

To test serum prostate-specific antigen (PSA) isoform [-2]proPSA (p2PSA), p2PSA/free PSA (%p2PSA) and Prostate Health Index (PHI) accuracy in predicting prostate cancer in obese men and to test whether PHI is more accurate than PSA in predicting prostate cancer in obese patients.

PATIENTS AND METHODS

The analysis consisted of a nested case-control study from the pro-PSA Multicentric European Study (PROMEtheuS) project. The study is registered at http://www.controlled-trials.com/ISRCTN04707454. The primary outcome was to test sensitivity, specificity and accuracy (clinical validity) of serum p2PSA, %p2PSA and PHI, in determining prostate cancer at prostate biopsy in obese men [body mass index (BMI) ≥30 kg/m(2) ], compared with total PSA (tPSA), free PSA (fPSA) and fPSA/tPSA ratio (%fPSA). The number of avoidable prostate biopsies (clinical utility) was also assessed. Multivariable logistic regression models were complemented by predictive accuracy analysis and decision-curve analysis.

RESULTS

Of the 965 patients, 383 (39.7%) were normal weight (BMI <25 kg/m(2) ), 440 (45.6%) were overweight (BMI 25-29.9 kg/m(2) ) and 142 (14.7%) were obese (BMI ≥30 kg/m(2) ). Among obese patients, prostate cancer was found in 65 patients (45.8%), with a higher percentage of Gleason score ≥7 diseases (67.7%). PSA, p2PSA, %p2PSA and PHI were significantly higher, and %fPSA significantly lower in patients with prostate cancer (P < 0.001). In multivariable logistic regression models, PHI significantly increased accuracy of the base multivariable model by 8.8% (P = 0.007). At a PHI threshold of 35.7, 46 (32.4%) biopsies could have been avoided.

CONCLUSION

In obese patients, PHI is significantly more accurate than current tests in predicting prostate cancer.

Obese men have more advanced and more aggressive prostate cancer at time of surgery than non-obese men after adjusting for screening PSA level and age: results from two independent nested case-control studies

BACKGROUND:

It remains unclear whether the hemodilution effect of body mass index (BMI) on PSA levels translates to inappropriate prostate cancer (PCa) screening in obese men. To address this, we conducted two nested case–control studies within prospective cohorts of men undergoing radical prostatectomy for newly diagnosed PCa.

METHODS:

We identified 1817 men with BMI ⩾30 kg m⁻² (cases) and 1244 men with BMI <25 kg m⁻² (controls) who underwent surgery to treat PCa at Mayo Clinic in Rochester between 2000 and 2009. Cases and controls were frequency matched on age and PSA level. In a similar manner, we identified 206 cases and 133 controls treated at Mayo Clinic in Florida between 2006 and 2011. We employed logistic regression models to evaluate the association of pathologic features of aggressiveness with obesity status.

RESULTS:

After adjusting for age and PSA level, we noted that obese men in the Rochester population are more likely to present with Gleason grade 8–10 tumors (OR= 1.50; 95% CI 1.14–1.96; P=0.003) and pT3, pT4, pTxN+ stage disease (OR=1.30; 95% CI 1.05–1.62). We noted a similar association seminal vesicle involvement (OR= 1.41; 95% CI 1.03–1.92; P=0.03). Results from the smaller Florida population supported these same associations but did not achieve conventional statistical significance.

CONCLUSIONs:

Obese men present with more aggressive PCa tumors compared with non-obese men of similar age and PSA screening values. If confirmed, this would support the need to explore PSA-based screening in obese men to possibly account for a hemodilution effect.