Indication to pelvic lymph nodes dissection for prostate cancer: the role of multiparametric magnetic resonance imaging when the risk of lymph nodes invasion according to Briganti updated nomogram is <5%

Development of a novel nomogram to identify the candidate to extended pelvic lymph node dissection in patients who underwent mpMRI and target biopsy only

BACKGROUND

Nowadays a tool able to predict the risk of lymph-node invasion (LNI) in patients underwent target biopsy (TB) only before radical prostatectomy (RP) is still lacking. Our aim is to develop a model based on mp-MRI and target biopsy (TB) alone able to predict the risk of LNI.

METHODS

We retrospectively extracted data of patients with preoperative positive mp-MRI and TB only who underwent RARP with ePLND from April 2014 to March 2020. A logistic regression model was performed to evaluate the impact of pre- and intra-operative factors on the risk of LNI. Model discrimination was assessed using an area under (AUC) the ROC curve. A nomogram, and its calibration plot, to predict the risk of LNI were generated based on the logistic model. A validation of the model was done using a similar cohort.

RESULTS

461 patients were included, of which 52 (11.27) had LNI. After logistic regression analysis and multivariable model DRE, PI-RADS, seminal vesicle invasion, PSA and worst GS at I and II target lesions were significant predictors of LNI. The AUC was 0.74 [0.67-0.81] 95% CI. The calibration plot shows that our model is very close to the ideal one which is in the 95% CI. After the creation of a visual nomogram, the cut-off to discriminate between the risk or not of LNI was set with Youden index at 60 points that correspond to a risk of LNI of 7%. The model applied on a similar cohort shown a LH+ of 2.58 [2.17-2.98] 95% CI.

CONCLUSIONS

Our nomogram for patients undergoing MRI-TB only takes into account clinical stage, SVI at MRI, biopsy Gleason pattern and PSA and it is able to identify patients with risk of LNI when a score higher than 7% is achieved.

Patients with Positive Lymph Nodes after Radical Prostatectomy and Pelvic Lymphadenectomy—Do We Know the Proper Way of Management?

Simple Summary

Prostate cancer (PCa) is the second most frequent malignancy in the male population worldwide. Men with a nodal invasion established after radical prostatectomy with lymph node dissection are a heterogeneous group of patients who require more thorough stratification and therapy individualization, which remain uncovered by current guidelines. Considering a multitude of prognostic factors and novel diagnostic techniques, classifying patients into narrower and more specified risk groups should be a vital part of lymph node positive PCa management in the future.

Abstract

Lymph node invasion in prostate cancer is a significant prognostic factor indicating worse prognosis. While it significantly affects both survival rates and recurrence, proper management remains a controversial and unsolved issue. The thorough evaluation of risk factors associated with nodal involvement, such as lymph node density or extracapsular extension, is crucial to establish the potential expansion of the disease and to substratify patients clinically. There are multiple strategies that may be employed for patients with positive lymph nodes. Nowadays, therapeutic methods are generally based on observation, radiotherapy, and androgen deprivation therapy. However, the current guidelines are incoherent in terms of the most effective management approach. Future management strategies are expected to make use of novel diagnostic tools and therapies, such as photodynamic therapy or diagnostic imaging with prostate-specific membrane antigen. Nevertheless, this heterogeneous group of men remains a great therapeutic concern, and both the clarification of the guidelines and the optimal substratification of patients are required.

Integration of clinicopathologic identification and deep transferrable image feature representation improves predictions of lymph node metastasis in prostate cancer

Background

Accurate identification of pelvic lymph node metastasis (PLNM) in patients with prostate cancer (PCa) is crucial for determining appropriate treatment options. Here, we built a PLNM-Risk calculator to obtain a precisely informed decision about whether to perform extended pelvic lymph node dissection (ePLND).

Methods

The PLNM-Risk calculator was developed in 280 patients and verified internally in 71 patients and externally in 50 patients by integrating a set of radiologists’ interpretations, clinicopathological factors and newly refined imaging indicators from MR images with radiomics machine learning and deep transfer learning algorithms. Its clinical applicability was compared with Briganti and Memorial Sloan Kettering Cancer Center (MSKCC) nomograms.

Findings

The PLNM-Risk achieved good diagnostic discrimination with areas under the receiver operating characteristic curve (AUCs) of 0.93 (95% CI, 0.90-0.96), 0.92 (95% CI, 0.84-0.97) and 0.76 (95% CI, 0.62-0.87) in the training/validation, internal test and external test cohorts, respectively. If the number of ePLNDs missed was controlled at < 2%, PLNM-Risk provided both a higher number of ePLNDs spared (PLNM-Risk 59.6% vs MSKCC 44.9% vs Briganti 38.9%) and a lower number of false positives (PLNM-Risk 59.3% vs MSKCC 70.1% and Briganti 72.7%). In follow-up, patients stratified by the PLNM-Risk calculator showed significantly different biochemical recurrence rates after surgery.

Interpretation

The PLNM-Risk calculator offers a noninvasive clinical biomarker to predict PLNM for patients with PCa. It shows improved accuracy of diagnosis support and reduced overtreatment burdens for patients with findings suggestive of PCa.

Funding

This work was supported by the Key Research and Development Program of Jiangsu Province (BE2017756) and the Suzhou Science and Technology Bureau-Science and Technology Demonstration Project (SS201808).

External validation of the Memorial Sloan Kettering Cancer Centre and Briganti nomograms for the prediction of lymph node involvement of prostate cancer using clinical stage assessed by magnetic resonance imaging

OBJECTIVES

To evaluate the impact of using clinical stage assessed by multiparametric magnetic resonance imaging (mpMRI) on the performance of two established nomograms for the prediction of pelvic lymph node involvement (LNI) in patients with prostate cancer.

PATIENTS AND METHODS

Patients undergoing robot-assisted extended pelvic lymph node dissection (ePLND) from 2015 to 2019 at three teaching hospitals were retrospectively evaluated. Risk of LNI was calculated four times for each patient, using clinical tumour stage (T-stage) assessed by digital rectal examination (DRE) and by mpMRI, in the Memorial Sloan Kettering Cancer Centre (MSKCC; 2018) and Briganti (2012) nomograms. Discrimination (area under the curve [AUC]), calibration, and the net benefit of these four strategies were assessed and compared.

RESULTS

A total of 1062 patients were included, of whom 301 (28%) had histologically proven LNI. Using DRE T-stage resulted in AUCs of 0.71 (95% confidence interval [CI] 0.70-0.72) for the MSKCC and 0.73 (95% CI 0.72-0.74) for the Briganti nomogram. Using mpMRI T-stage, the AUCs were 0.72 (95% CI 0.71-0.73) for the MSKCC and 0.75 (95% CI 0.74-0.76) for the Briganti nomogram. mpMRI T-stage resulted in equivalent calibration compared with DRE T-stage. Combined use of mpMRI T-stage and the Briganti 2012 nomogram was shown to be superior in terms of AUC, calibration, and net benefit. Use of mpMRI T-stage led to increased sensitivity for the detection of LNI for all risk thresholds in both models, countered by a decreased specificity, compared with DRE T-stage.

CONCLUSION

T-stage as assessed by mpMRI is an appropriate alternative for T-stage assessed by DRE to determine nomogram-based risk of LNI in patients with prostate cancer, and was associated with improved model performance of both the MSKCC 2018 and Briganti 2012 nomograms.

Nomograms in Urologic Oncology: Lights and Shadows

Decision-making in urologic oncology involves integrating multiple clinical data to provide an answer to the needs of a single patient. Although the practice of medicine has always been an “art” involving experience, clinical data, scientific evidence and judgment, the creation of specialties and subspecialties has multiplied the challenges faced every day by physicians. In the last decades, with the field of urologic oncology becoming more and more complex, there has been a rise in tools capable of compounding several pieces of information and supporting clinical judgment and experience when approaching a difficult decision. The vast majority of these tools provide a risk of a certain event based on various information integrated in a mathematical model. Specifically, most decision-making tools in the field of urologic focus on the preoperative or postoperative phase and provide a prognostic or predictive risk assessment based on the available clinical and pathological data. More recently, imaging and genomic features started to be incorporated in these models in order to improve their accuracy. Genomic classifiers, look-up tables, regression trees, risk-stratification tools and nomograms are all examples of this effort. Nomograms are by far the most frequently used in clinical practice, but are also among the most controversial of these tools. This critical, narrative review will focus on the use, diffusion and limitations of nomograms in the field of urologic oncology.

A narrative review of pelvic lymph node dissection in prostate cancer

Pelvic lymph node dissection (PLND) is an important component in the staging and prognostication of prostate cancer. We performed a narrative review to assess the literature surrounding PLND: (I) the current guideline recommendations and contemporary utilization, (II) the calculation of patient-specific risk to perform PLND using available nomograms, (III) to review the extent of dissection, and its associated outcomes and complications. Due to the improved lymph node yield, better staging, and theoretical improvement in the control of micro-metastatic disease, guidelines have supported the use of (extended-) PLND in patients deemed to be at intermediate or high risk of lymph node involvement (often at a threshold of 5% on modern risk nomograms). However, in practice, real-world utilization of PLND varies considerably due to multiple reasons. Conflicting evidence persists with no clear oncological benefit to PLND, and a small, but important, risk of morbidity. Complications are rare, but include lymphoceles; thromboembolic events; and more rarely, obturator nerve, vascular, and ureteric injury. Furthermore, changing disease incidence and stage migration in the context of earlier detection overall have led to a decreased risk of nodal disease. The trade-offs between the benefits, harms, and risk tolerance/threshold must be carefully considered between each patient and their clinician.

Comparison of cross-sectional imaging techniques for the detection of prostate cancer lymph node metastasis: a critical review

Conventional staging for prostate cancer (PCa) is performed for men diagnosed with unfavorable-intermediate or higher risk disease. Computed tomography (CT) of the abdomen and pelvis and whole body bone scan remains the standard of care for the detection of visceral, nodal, and bone metastasis. The implementation of the 2012 United States Preventive Services Task Force recommendation against routine prostate specific antigen (PSA) screening resulted in a rise of metastatic PCa at the time of diagnosis, emphasizing the importance of effective imaging modalities for evaluating metastatic disease. CT plays a major role in clinical staging at the time of PCa diagnosis, but multi-parametric magnetic resonance imaging (MRI) is now integrated into many prostate biopsy protocols for the detection of primary PCa, and may be a surrogate for CT for nodal staging. Current guidelines incorporate both CT and MRI as appropriate cross-sectional imaging modalities for the identification of nodal metastasis in indicated patients. There is an ongoing debate about the utility of traditional cross-sectional imaging modalities as well as advanced imaging modalities in detection of both organ-confined PCa detection and nodal involvement.

A machine learning-assisted decision-support model to better identify patients with prostate cancer requiring an extended pelvic lymph node dissection

OBJECTIVES

To develop a machine learning (ML)-assisted model to identify candidates for extended pelvic lymph node dissection (ePLND) in prostate cancer by integrating clinical, biopsy, and precisely defined magnetic resonance imaging (MRI) findings.

PATIENTS AND METHODS

In all, 248 patients treated with radical prostatectomy and ePLND or PLND were included. ML-assisted models were developed from 18 integrated features using logistic regression (LR), support vector machine (SVM), and random forests (RFs). The models were compared to the Memorial SloanKettering Cancer Center (MSKCC) nomogram using receiver operating characteristic-derived area under the curve (AUC) calibration plots and decision curve analysis (DCA).

RESULTS

A total of 59/248 (23.8%) lymph node invasions (LNIs) were identified at surgery. The predictive accuracy of the ML-based models, with (+) or without (-) MRI-reported LNI, yielded similar AUCs (RFs⁺ /RFs^- : 0.906/0.885; SVM⁺ /SVM^- : 0.891/0.868; LR⁺ /LR^- : 0.886/0.882) and were higher than the MSKCC nomogram (0.816; P < 0.001). The calibration of the MSKCC nomogram tended to underestimate LNI risk across the entire range of predicted probabilities compared to the ML-assisted models. The DCA showed that the ML-assisted models significantly improved risk prediction at a risk threshold of ≤80% compared to the MSKCC nomogram. If ePLNDs missed was controlled at <3%, both RFs⁺ and RFs^- resulted in a higher positive predictive value (51.4%/49.6% vs 40.3%), similar negative predictive value (97.2%/97.8% vs 97.2%), and higher number of ePLNDs spared (56.9%/54.4% vs 43.9%) compared to the MSKCC nomogram.

CONCLUSIONS

Our ML-based model, with a 5-15% cutoff, is superior to the MSKCC nomogram, sparing ≥50% of ePLNDs with a risk of missing <3% of LNIs.

Susceptibility Perturbation MRI Maps Tumor Infiltration into Mesorectal Lymph Nodes

Noninvasive characterization of lymph node involvement in cancer is an enduring onerous challenge. In rectal cancer, pathologic lymph node status constitutes the most important determinant of local recurrence and overall survival, and patients with involved lymph nodes may benefit from preoperative chemo and/or radiotherapy. However, knowledge of lymph node status before surgery is currently hampered by limited imaging accuracy. Here, we introduce Susceptibility-Perturbation MRI (SPI) as a novel source of contrast to map malignant infiltration into mesorectal lymph nodes. SPI involves multigradient echo (MGE) signal decays presenting a nonmonoexponential nature, which we show is sensitive to the underlying microstructure via susceptibility perturbations. Using numerical simulations, we predicted that the large cell morphology and the high cellularity of tumor within affected mesorectal lymph nodes would induce signature SPI decays. We validated this prediction in mesorectal lymph nodes excised from total mesorectal excision specimens of patients with rectal cancer using ultrahigh field (16.4 T) MRI. SPI signals distinguished benign from malignant nodal tissue, both qualitatively and quantitatively, and our histologic analyses confirmed cellularity and cell size were the likely underlying sources for the differences observed. SPI was then adapted to a clinical 1.5 T scanner, added to patients' staging protocol, and compared with conventional assessment by two expert radiologists. Nonmonoexponential decays, similar to those observed in the ex vivo study, were demonstrated, and SPI classified lymph nodes more accurately than standard high-resolution T₂-weighted imaging assessment. These findings suggest this simple, yet highly informative, method can improve rectal cancer patient selection for neoadjuvant therapy. SIGNIFICANCE: These findings introduce an MRI methodology tailored to detect magnetic susceptibility perturbations induced by subtle alterations in tissue microstructure.

The impact of lymphovascular invasion in patients with prostate cancer following radical prostatectomy and its association with their clinicopathological features: An updated PRISMA-compliant systematic review and meta-analysis

OBJECTIVE

Numerous studies have shown that lymphovascular invasion (LVI) is linked to biochemical recurrence (BCR) in prostate cancer (PCa) patients following radical prostatectomy (RP). However, the actual clinicopathological impacts of LVI remain unclear. Thus, we performed a meta-analysis to evaluate the pathologic and prognostic impacts of LVI in PCa patients.

METHODS

Following the guidance of the PRISMA statement, relevant studies were collected systematically from the PubMed, EMBASE, and Web of Science databases to identify relevant studies published before June 2018. The hazard ratios (HRs) and 95% confidence intervals (95% CIs) were calculated to investigate the association of LVI with BCR and clinicopathological features.

RESULTS

A total of 20 studies including 25,570 patients (106-6678 per study) with PCa were incorporated into this meta-analysis. Overall pooled analysis suggested that LVI was associated with a higher BCR risk both in univariate (pooled HR=1.50, 95% CI: 1.34-1.68, P <.001) and multivariate analyses (pooled HR=1.25, 95% CI: 1.17-1.34, P <.001). In addition, LVI was closely correlated with extraprostatic extension (yes vs no: OR = 4.23, 95% CI: 1.86-9.61, P <.001), pathological GS (≥7 vs <7: OR = 5.46, 95% CI: 2.25-13.27, P <.001), lymph node metastases (yes vs no: OR = 18.56, 95% CI: 7.82-44.06, P <.001), higher pathological stage (≥ T3 vs < T2: OR = 6.75, 95% CI: 5.46-8.36, P <.001), positive surgical margin (positive vs negative: OR = 2.42, 95% CI: 1.57-3.72, P <.001) and seminal vesicle invasion (yes vs no: OR = 5.72, 95% CI: 2.45-13.36, P <.001).

CONCLUSIONS

This study suggests that LVI in histopathology is associated with a higher risk of BCR and advanced clinicopathological features in PCa patients and could serve as a poor prognostic factor in patients who underwent RP.

The role of side-specific biopsy and dominant tumor location at radical prostatectomy in predicting the side of nodal metastases in organ confined prostate cancer: is lymphatic spread really unpredictable?

BACKGROUND

The aim of this study was to evaluate the correlation between the location of prostate cancer (PCa) either at biopsy or at radical prostatectomy (RP) specimens and the side of positive lymph nodes (LNs). Furthermore, we assessed the risk of contralateral LN metastasis (LNMs) in patients with unilateral positive biopsy and/or dominant lesion at RP.

METHODS

We reviewed retrospectively our prospectively maintained database of patients with LNM treated with robot-assisted RP and bilateral robot-assisted extended pelvic lymph node dissection (EPLND) for PCa from January 2014 to May 2018 at a surgical high-volume center. All men with a suspicion for PCa underwent a 12-cores prostate biopsy. In case of a first negative biopsy but the persistence of suspicion, all the patients underwent prostate multiparametric magnetic resonance imaging (mpMRI) and subsequently either fusion targeted biopsy (TBx) or systematic standard biopsy (SBx), in case of positive or negative mpMRI, respectively. All patients underwent a robot-assisted RP. Whole-mount histological sections resected from the RP specimens were used as reference standards.

RESULTS

Eighty-seven patients were enrolled for the study. Median number of LNs retrieved per patient was 26, specifically 13 and 12, on the left and right side, respectively. Seven of 24 (29.1%) right lobe positive biopsy showed positive LNs on the left side (one exclusively left, 6 bilateral LNMs). Again, 12 of 26 (46.1%) left lobe positive biopsy showed positive LNs on the right side (one exclusively right, 11 bilateral LNMs). No significant differences of performance to predict the side of LNMs were recorded in the SBx and TBx groups. Concerning RP specimens, only five of 22 (22.7%) right lobe dominant cases showed positive LNs on the left side (two exclusively left, 3 bilateral LN metastases). Again, none of 16 left lobe dominant cases showed positive LNs on the contralateral side (15 exclusively right, 1 bilateral LNMs).

CONCLUSIONS

Our results suggest confirmed that a unilateral LN dissection limited to the tumor-bearing side of the gland evaluated by biopsy specimens should not be recommended due to the substantial risk of missing contralateral LNMs.