Predictive factors for lymph node positivity in patients undergoing extended pelvic lymphadenectomy during robot assisted radical prostatectomy

Development and internal validation of preoperative and postoperative nomograms predicting quadrifecta outcomes following robotic radical prostatectomy

INTRODUCTION

Literature on the factors predicting functional and oncological outcomes following robot-assisted radical prostatectomy (RARP) is sparse for the Indian population. Hence, the primary objective of this study was to develop preoperative and postoperative nomograms predicting these outcomes in patients with prostate cancer undergoing RARP.

METHODS

This retrospective analysis identified the predictors of quadrifecta outcomes, i.e., the patients who did not have complications, were continent, had negative surgical margins, and were biochemical recurrence free with at least 1 year of follow-up following RARP. We excluded the return of sexual potency as the majority of the patients in our series were sexually inactive preoperatively. We used the backward stepwise logistic regression analysis method to identify the predictors of quadrifecta. Preoperative and postoperative nomograms using these predictors were developed and validated with bootstrapping, goodness of fit, calibration plot, decision curve analysis (DCA), and theits receiver operating characteristic (ROC) analysis.

RESULTS

Of the 688 patients who underwent RARP, 399 were included in this study, and 123 (30.8%) of these achieved the quadrifecta outcomes. Preoperative nomogram was developed using four variables, i.e., prostate-specific antigen (PSA), Charlson Comorbidity Index (CCI), biopsy Gleason score, and clinical stage. Postoperative nomogram included PSA, CCI, pathological tumor stage, tumor grade, and positive lymph node. Both the models were internally valid on bootstrapping, calibration plots, and goodness of fit. On the ROC analysis, preoperative and postoperative nomograms had an area under the curve of 0.71 and 0.79, respectively. On the DCA, at a threshold probability of 5%, both the models showed a net benefit.

CONCLUSIONS

We developed and validated accurate nomograms for predicting quadrifecta outcomes following RARP for the Indian population.

A comparison between 68Ga-labeled prostate-specific membrane antigen-PET/CT and multiparametric MRI for excluding regional metastases prior to radical prostatectomy

OBJECTIVES

To compare the ability of ⁶⁸Ga -PSMA PET/CT (PSMA PET/CT) and multiparametric MRI (mpMRI) to exclude lymph node invasion (LNI) in patients who undergo radical prostatectomy (RP).

MATERIALS AND METHODS

A multicenter cohort of patients who underwent PSMA PET/CT and pelvic mpMRI prior to RP with pelvic lymph node dissection (PLND) was analyzed. Increased Ga68-PSMA uptake on PET/CT and enlarged (> 10 mm) or abnormal lymph nodes on mpMRI were considered positive findings. The final surgical pathology served as the standard of reference. The negative predictive value (NPV) was calculated for each modality separately, as well as the combined value.

RESULTS

Included were 89 patients with D'Amico intermediate (45%) or high-risk (55%) prostate cancer. The median number of extracted LN was 9 (IQR 6-14). LNI was found in 12 (13.5%) patients. The NPV of mpMRI, PSMA PET/CT, and the two tests combined were 87%, 89%, and 90%, in the entire cohort, 95%, 97%, and 97% in patients with intermediate-risk disease, and 80%, 82%, and 83% in patients with high-risk disease, respectively. The median diameter of LN missed by both imaging and the median intranodal tumor diameter was 5.5 (IQR 3-10) mm and 1 (IQR 1-3) mm, respectively.

CONCLUSIONS

PSMA PET/CT and mpMRI demonstrated similar performance in excluding pelvic LNI with NPV of approximately 90%. The combination of both tests does not improve NPV significantly. Therefore, even in the era of advanced imaging, PLND is still recommended for accurate staging, especially in the high-risk population.

MRI and 11C Acetate PET/CT for Prediction of Regional Lymph Node Metastasis in Newly Diagnosed Prostate Cancer

Background

The aim of the study was to examine the value of quantitative and qualitative MRI and ¹¹C acetate PET/CT parameters in predicting regional lymph node (LN) metastasis of newly diagnosed prostate cancer (PCa).

Patients and methods

Patients with intermediate (n = 6) and high risk (n = 47) PCa underwent 3T MRI (40 patients) and ¹¹C acetate PET/CT (53 patients) before extended pelvic LN dissection. For each patient the visually most suspicious LN was assessed for mean apparent diffusion coefficient (ADCmean), maximal standardized uptake value (SUVmax), size and shape and the primary tumour for T stage on MRI and ADCmean and SUVmax in the index lesion. The variables were analysed in simple and multiple logistic regression analysis.

Results

All variables, except ADCmean and SUVmax of the primary tumor, were independent predictors of LN metastasis. In multiple logistic regression analysis the best model was ADCmean in combintion with MRI T-stage where both were independent predictors of LN metastasis, this combination had an AUC of 0.81 which was higher than the AUC of 0.65 for LN ADCmean alone and the AUC of 0.69 for MRI T-stage alone.

Conclusions

Several quantitative and qualitative imaging parameters are predictive of regional LN metastasis in PCa. The combination of ADCmean in lymph nodes and T-stage on MRI was the best model in multiple logistic regression with increased predictive value compared to lymph node ADCmean and T-stage on MRI alone.

Multiparametric magnetic resonance imaging-transrectal ultrasound fusion prostate biopsy: A prospective, single centre study

Introduction:

Transrectal rectal ultrasound (TRUS)-guided systematic biopsy is the gold standard for diagnosis of prostate cancer. However, systematic biopsy has high false-negative rate and often misses anteriorly located tumors. Magnetic resonance imaging (MRI)-TRUS fusion biopsy can potentially improve cancer detection by better visualization and targeting of cancer focus. We evaluated the role of fusion biopsy in detection of prostate cancer and the association of prostate imaging reporting and data system (PI-RADS) score for predicting cancer risk and its aggression.

Methods:

Ninety-six consecutive men with suspected prostate cancer underwent MRI-TRUS fusion-targeted biopsy of suspicious lesions and standard 12 core biopsy from May 2014 to July 2015 in our institution. All patients underwent 3.0 T multiparametric MRI before biopsy. mp-MRI included T2W, DWI, DCE and MRS sequences to identify lesions suspicious for prostate cancer. Suspected lesions were scored according to PI-RADS scoring system. Comparison of cancer detection between standard 12 core biopsy and MRI-TRUS fusion biopsy was done. Detection of prostate cancer was primary end point of this study.

Results:

Mean age was 64.4 years and median prostate-specific antigen was 8.6 ng/ml. Prostate cancer was detected in 57 patients (59.3%). Of these 57 patients, 8 patients (14%) were detected by standard 12 core biopsy only, 7 patients (12.3%) with MRI-TRUS fusion biopsy only, and 42 patients (73.7%) by both techniques. Of the 7 patients, detected with MRI-TRUS fusion biopsy alone, 6 patients (85.7%) had Gleason ≥7 disease. Prostate cancer was detected on either standard 12 core biopsy or MRI-TRUS fusion biopsy in 0%, 42.8%, 74%, and 89.3% patients of suspicious lesions of highest PI-RADS score 2, 3, 4, and 5, respectively.

Conclusions:

MRI-TRUS fusion prostate biopsy improves cancer detection rate when combined with standard 12 cores biopsy and detects more intermediate or high-grade prostate cancer (Gleason ≥7). With increasing PI-RADS score, there is an increase chance of detection of cancer as well as its aggressiveness.