Is it necessary to remove the seminal vesicles completely at radical prostatectomy? decision curve analysis of European Society of Urologic Oncology criteria

Decision curve analysis confirms higher clinical utility of multi-domain versus single-domain prediction models in patients with open abdomen treatment for peritonitis

BACKGROUND

Prediction modelling increasingly becomes an important risk assessment tool in perioperative systems approaches, e.g. in complex patients with open abdomen treatment for peritonitis. In this population, combining predictors from multiple medical domains (i.e. demographical, physiological and surgical variables) outperforms the prediction capabilities of single-domain prediction models. However, the benefit of these prediction models for clinical decision-making remains to be investigated. We therefore examined the clinical utility of mortality prediction models in patients suffering from peritonitis with a decision curve analysis.

METHODS

In this secondary analysis of a large dataset, a traditional logistic regression approach, three machine learning methods and a stacked ensemble were employed to examine the predictive capability of demographic, physiological and surgical variables in predicting mortality under open abdomen treatment for peritonitis. Calibration was examined with calibration belts and predictive performance was assessed with the area both under the receiver operating characteristic curve (AUROC) and under the precision recall curve (AUPRC) and with the Brier Score. Clinical utility of the prediction models was examined by means of a decision curve analysis (DCA) within a treatment threshold range of interest of 0-30%, where threshold probabilities are traditionally defined as the minimum probability of disease at which further intervention would be warranted.

RESULTS

Machine learning methods supported available evidence of a higher prediction performance of a multi- versus single-domain prediction models. Interestingly, their prediction performance was similar to a logistic regression model. The DCA demonstrated that the overall net benefit is largest for a multi-domain prediction model and that this benefit is larger compared to the default "treat all" strategy only for treatment threshold probabilities above about 10%. Importantly, the net benefit for low threshold probabilities is dominated by physiological predictors: surgical and demographics predictors provide only secondary decision-analytic benefit.

CONCLUSIONS

DCA provides a valuable tool to compare single-domain and multi-domain prediction models and demonstrates overall higher decision-analytic value of the latter. Importantly, DCA provides a means to clinically differentiate the risks associated with each of these domains in more depth than with traditional performance metrics and highlighted the importance of physiological predictors for conservative intervention strategies for low treatment thresholds. Further, machine learning methods did not add significant benefit either in prediction performance or decision-analytic utility compared to logistic regression in these data.

Predicting the occurrence of multidrug-resistant organism colonization or infection in ICU patients: development and validation of a novel multivariate prediction model

Background

Multidrug-resistant organisms (MDROs) have emerged as an important cause of poor prognoses of patients in the intensive care unit (ICU). This study aimed to establish an easy-to-use nomogram for predicting the occurrence of MDRO colonization or infection in ICU patients.

Methods

In this study, we developed a nomogram based on predictors in patients admitted to the ICU in the First Affiliated Hospital of Xiamen University from 2016 to 2018 using univariate and multivariate logistic regression analysis. We externally validated this nomogram in patients from another hospital over a similar period, and assessed its performance by calculating the area under the receiver operating characteristic (ROC) curve (AUC) and performing a decision curve analysis.

Results

331 patients in the primary cohort and 181 patients in the validation cohort were included in the statistical analysis. Independent factors derived from the primary cohort to predict MDRO colonization or infection were male sex, higher C-reactive protein (CRP) levels and higher Pitt bacteremia scores (Pitt scores), which were all assembled in the nomogram. The nomogram yielded good discrimination with an AUC of 0.77 (95% CI 0.70–0.84), and the range of threshold probabilities of decision curves was approximately 30–95%.

Conclusion

This easy-to-use nomogram is potentially useful for predicting the occurrence of MDRO colonization or infection in ICU patients.

Assessing the Clinical Impact of Risk Models for Opting Out of Treatment

Decision curves are a tool for evaluating the population impact of using a risk model for deciding whether to undergo some intervention, which might be a treatment to help prevent an unwanted clinical event or invasive diagnostic testing such as biopsy. The common formulation of decision curves is based on an opt-in framework. That is, a risk model is evaluated based on the population impact of using the model to opt high-risk patients into treatment in a setting where the standard of care is not to treat. Opt-in decision curves display the population net benefit of the risk model in comparison to the reference policy of treating no patients. In some contexts, however, the standard of care in the absence of a risk model is to treat everyone, and the potential use of the risk model would be to opt low-risk patients out of treatment. Although opt-out settings were discussed in the original decision curve paper, opt-out decision curves are underused. We review the formulation of opt-out decision curves and discuss their advantages for interpretation and inference when treat-all is the standard.

Neuro-anatomic basis of potency recovery after radical prostatectomy: an expert's point of view

INTRODUCTION

From 25% to 95% of those who have undergone radical prostatectomy (RP) report erectile dysfunction 12 months after surgery. We attempt a review of the available evidence regarding the anatomy of the cavernous nerves and the surgical refinements to enhance sexual function recovery after surgery.

EVIDENCE ACQUISITION

The PubMed/Medline database was searched. Duplicates were removed. Studies were selected by the authors according to the aim of the present review.

EVIDENCE SYNTHESIS

The cavernous nerves are deemed responsible for erections, but their exact function is still a matter of debate. They do not necessarily have the same distribution in all individuals: in most the cases, these nerves are located posterolaterally, however, it is not uncommon to find some fibers on the anterolateral aspects of the prostate, especially towards the apex. Several technical strategies were proposed in order to intraoperatively identify and spare the neurovascular bundles: despite all efforts, clinical results are still only partially satisfying.

CONCLUSIONS

The recovery of potency is one of the most unpredictable outcomes after RP. The advent of the robotic surgical system seems to have brought a trend towards a faster recovery of erectile function.

Assessing the Clinical Impact of Risk Prediction Models With Decision Curves: Guidance for Correct Interpretation and Appropriate Use

The decision curve is a graphical summary recently proposed for assessing the potential clinical impact of risk prediction biomarkers or risk models for recommending treatment or intervention. It was applied recently in an article in Journal of Clinical Oncology to measure the impact of using a genomic risk model for deciding on adjuvant radiation therapy for prostate cancer treated with radical prostatectomy. We illustrate the use of decision curves for evaluating clinical- and biomarker-based models for predicting a man's risk of prostate cancer, which could be used to guide the decision to biopsy. Decision curves are grounded in a decision-theoretical framework that accounts for both the benefits of intervention and the costs of intervention to a patient who cannot benefit. Decision curves are thus an improvement over purely mathematical measures of performance such as the area under the receiver operating characteristic curve. However, there are challenges in using and interpreting decision curves appropriately. We caution that decision curves cannot be used to identify the optimal risk threshold for recommending intervention. We discuss the use of decision curves for miscalibrated risk models. Finally, we emphasize that a decision curve shows the performance of a risk model in a population in which every patient has the same expected benefit and cost of intervention. If every patient has a personal benefit and cost, then the curves are not useful. If subpopulations have different benefits and costs, subpopulation-specific decision curves should be used. As a companion to this article, we released an R software package called DecisionCurve for making decision curves and related graphics.

The European Association of Urology Robotic Urology Section (ERUS) survey of robot-assisted radical prostatectomy (RARP)

OBJECTIVE

To evaluate surgeons adherence to current clinical practice, with the available evidence, for robot-assisted radical prostatectomy (RARP) and offer a baseline assessment to measure the impact of the Pasadena recommendations. Recently, the European Association of Urology Robotic Urology Section (ERUS) supported the Pasadena Consensus Conference on best practices in RARP.

SUBJECTS AND METHODS

This survey was performed in January 2012. A specific questionnaire was sent, by e-mail, to 145 robotic surgeons who were included in the mailing-list of ERUS members and working in different urological institutions. Participating surgeons were invited to answer a multiple-choice questionnaire including 24-items evaluating the main RARP surgical steps.

RESULTS

In all, 116 (79.4%) invited surgeons answered the questionnaire and accepted to participate to the ERUS survey. In all, 47 (40.5%) surgeons performed >100 RARPs; 41 (35.3%) between 50 and 100, and 28 (24.1%) <50 yearly. The transperitoneal, antegrade technique was the preferred approach. Minimising bladder neck dissection and the use of athermal dissection of the neurovascular bundles (NVBs) were also popular. There was more heterogeneity in the use of energy for seminal vesicle dissection, the preservation of the tips of the seminal vesicle and the choice between intra- and interfascial planes during the antero-lateral dissection of the NVBs. There was also large variability in the posterior and/or anterior reconstruction steps.

CONCLUSIONS

The present study is the first international survey evaluating surgeon preferences during RARP. Considering that the results were collected before the publication of the Pasadena recommendations, the data might be considered an important baseline evaluation to test the dissemination and effects of the Pasadena recommendations in subsequent years.

Radical prostatectomy, sparing of the seminal vesicles, and painful orgasm

INTRODUCTION

Erectile dysfunction has been widely investigated as the major factor responsible for sexual bother in patients after radical prostatectomy (RP); painful orgasm (PO) is one element of this bother, but little is known about its prevalence and its effects on sexual health.

AIM

This study aims to investigate the prevalence of PO and to identify potential risk factors.

MAIN OUTCOME MEASURES

A total of 1,411 consecutive patients underwent open (radical retropubic prostatectomy) or robot-assisted laparoscopic RP between 2002 and 2006. The patients were asked to complete a study-specific questionnaire.

METHODS

Of a total of 145 questions, 5 dealt with the orgasmic characteristics. The questionnaire was also administered to a comparison group of 442 persons, matched for age and area of residency.

RESULTS

The response rate was 91% (1,288 patients). A total of 143 (11%) patients reported PO. Among the 834 men being able to have an orgasm, the prevalence was 18% vs. 6% in the comparison group (relative risk [RR] 2.8, 95% confidence interval [CI] 1.7-4.5). When analyzed as independent variables, bilateral seminal vesicle (SV)-sparing approach (RR 2.33, 95% CI 1.0-5.3, P = 0.045) and age <60 years were significantly related to the presence of PO (95% CI 0.5-0.9, P = 0.019). After adjustment for age, bilateral SV-sparing still remained a significant predictor for occurrence of PO.

CONCLUSIONS

We found that PO occurs significantly more often in patients undergoing bilateral SV-sparing RP when compared with age-matched comparison population.

Best practices in robot-assisted radical prostatectomy: recommendations of the Pasadena Consensus Panel

CONTEXT

Radical retropubic prostatectomy (RRP) has long been the most common surgical technique used to treat clinically localized prostate cancer (PCa). More recently, robot-assisted radical prostatectomy (RARP) has been gaining increasing acceptance among patients and urologists, and it has become the dominant technique in the United States despite a paucity of prospective studies or randomized trials supporting its superiority over RRP.

OBJECTIVE

A 2-d consensus conference of 17 world leaders in prostate cancer and radical prostatectomy was organized in Pasadena, California, and at the City of Hope Cancer Center, Duarte, California, under the auspices of the European Association of Urology Robotic Urology Section to systematically review the currently available data on RARP, to critically assess current surgical techniques, and to generate best practice recommendations to guide clinicians and related medical personnel. No commercial support was obtained for the conference.

EVIDENCE ACQUISITION

A systematic review of the literature was performed in agreement with the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement.

EVIDENCE SYNTHESIS

The results of the systematic literature review were reviewed, discussed, and refined over the 2-d conference. Key recommendations were generated using a Delphi consensus approach. RARP is associated with less blood loss and transfusion rates compared with RRP, and there appear to be minimal differences between the two approaches in terms of overall postoperative complications. Positive surgical margin rates are at least equivalent with RARP, but firm conclusions about biochemical recurrence and other oncologic end points are difficult to draw because the follow-up in existing studies is relatively short and the overall experience with RARP in locally advanced PCa is still limited. RARP may offer advantages in postoperative recovery of urinary continence and erectile function, although there are methodological limitations in most studies to date and a need for well-controlled comparative outcomes studies of radical prostatectomy surgery following best practice guidelines. Surgeon experience and institutional volume of procedures strongly predict better outcomes in all relevant domains.

CONCLUSIONS

Available evidence suggests that RARP is a valuable therapeutic option for clinically localized PCa. Further research is needed to clarify the actual role of RARP in patients with locally advanced disease.

Comparison of three different tools for prediction of seminal vesicle invasion at radical prostatectomy

BACKGROUND

Statistical prediction tools are increasingly common, but there is considerable disagreement about how they should be evaluated. Three tools--Partin tables, the European Society for Urological Oncology (ESUO) criteria, and the Gallina nomogram--have been proposed for the prediction of seminal vesicle invasion (SVI) in patients with clinically localized prostate cancer who are candidates for a radical prostatectomy.

OBJECTIVES

Using different statistical methods, we aimed to determine which of these tools should be used to predict SVI.

DESIGN, SETTINGS, AND PARTICIPANTS

The independent validation cohort consisted of 2584 patients treated surgically for clinically localized prostate cancer at four North American tertiary care centers between 2002 and 2007.

INTERVENTIONS

Robot-assisted laparoscopic radical prostatectomy.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Primary outcome was the presence of SVI. Traditional (area under the receiver operating characteristic [ROC] curve, calibration plots, the Brier score, sensitivity and specificity, positive and negative predictive value) and novel (decision curve analysis and predictiveness curves) statistical methods quantified the predictive abilities of the three models.

RESULTS AND LIMITATIONS

Traditional statistical methods (ie, ROC plots and Brier scores) could not clearly determine which one of the three SVI prediction tools should be preferred. For example, ROC plots and Brier scores seemed biased against the binary decision tool (ESUO criteria) and gave discordant results for the continuous predictions of the Partin tables and the Gallina nomogram. The results of the calibration plots were discordant with those of the ROC plots. Conversely, the decision curve indicated that the Partin tables represent the best strategy for stratifying the risk of SVI, resulting in the highest net benefit within the whole range of threshold probabilities.

CONCLUSIONS

When predicting SVI, surgeons should prefer the Partin tables over the ESUO criteria and the Gallina nomogram because this tool provided the highest net benefit. In contrast to traditional statistical methods, decision curve analysis gave an unambiguous result applicable to both continuous and binary models, providing an insight into clinical utility.

Continence rate and oncological feasibility after total transurethral resection of the prostate as an alternative therapy for the treatment of prostate cancer: a pilot study

PURPOSE

The value of total transurethral resection of prostate cancer (TURPC) as an alternative therapy was first recognized by Hans J. Reuter. Thus, we conducted the study of prospectively collected data to verify total TURPC as an alternative therapy forlocalized prostate cancer.

METHODS

From January 2008 to July 2011, 14 patients with a mean age of 76.1 years (range, 66 to 89 years) with clinically localized prostate cancer were treated by prostatic resection by the corresponding author with curative intention.

RESULTS

The mean duration of TURPC was 51.7 minutes (range, 30 to 120 minutes) and the mean amount of prostatic tissue resected was 21.2 g (range, 5 to 66 g). An intra- and/or postoperative blood transfusion was necessary in 2 cases. Hyponatremia was found in 7 patients. Six months after TURPC, 3 cases of grade 1 and 1 case of grade 2 incontinence were observed. Three patients in the high-risk group did not achieve a prostate specific antigen (PSA) nadir of ≤0.2 ng/mL. PSA recurrence occurred in one case in our series. Newly developed lymph node or distant metastases were not observed during the follow-up period.

CONCLUSIONS

According to our results, transurethral resection for prostate cancer can be performed with reasonable oncological results. The PSA nadir levels, and rates of biochemical failure and postoperative complications, including incontinence, were comparable with the published results for other procedures. TURPC is also inexpensive and non-invasive, and requires short hospitalization and a short surgical time without vesicourethral anastomosis.

The triple clinicopathologic features to seminal vesicle-sparing radical prostatectomy

BACKGROUND AND PURPOSE

With the widespread early detection programs for prostate cancer, there has been a downward stage migration and a marked decrease in the percentage of men with seminal vesicle invasion (SVI) compared with previous data. We evaluated clinicopathologic findings that are associated with SVI to select patients for potential seminal vesicle-sparing surgery.

PATIENTS AND METHODS

We reviewed our radical prostatectomy database from 1997 to 2006 to evaluate the incidence and clinical correlates of SVI. Variables analyzed included serum prostate-specific antigen (PSA) level, clinical stage, percentage of positive cores with cancer, Gleason score on biopsy, age, prostate weight, and urethral and vesical surgical margins. Statistical analysis included univariate and multivariate logistic regressions.

RESULTS

Of 267 patients, 32 (12%) had SVI. Preoperative PSA level, biopsy Gleason score, and percentage of positive cores were highly predictive of SVI on multivariate analysis. SVI was present in only 1/98 patients (1.02 %) with biopsy Gleason score ≤6, 0/23 patients (0%) with serum PSA level <4 ng/mL, and only 1 patient with ≤12.8% of positive cores on biopsy. In all cases of distal SVI, there was proximal involvement.

CONCLUSION

Serum PSA level, Gleason score, and percentage of positive cores on biopsy are statistically significant predictors of SVI on multivariate analysis. Seminal vesiculectomy does not benefit almost 99% of patients with biopsy Gleason score ≤6, PSA level <4 ng/mL, and with <12% cores with cancer. In cases of seminal vesicle-sparing surgery, frozen section of the proximal portion may be of adjunct usefulness for the triple.