Identification of Factors Contributing to Testosterone Recovery After Hormone Therapy Combined With External Radiation Therapy.

BACKGROUND/AIM: When hormone therapy (HT) is combined with radiotherapy, understanding the recovery of testosterone levels after the end of HT becomes crucial for considering subsequent therapy. The aim of this study was to determine the factors influencing the time to recovery of testosterone levels after discontinuation of HT and the likelihood of recovery. PATIENTS AND METHODS: The study included a total of 108 patients with prostate cancer who were treated with GnRH agonist in combination with radiotherapy and followed up for at least 12 months after discontinuation of the GnRH agonist. The presence of recovery of testosterone levels and the time to recovery were investigated. Univariate and multivariate analyses were performed on several factors contributing to testosterone recovery, including age at initiation of HT, and the duration of HT. RESULTS: Testosterone levels recovered in 61 cases (56.5%). The median time to recovery was 14.8 months. There was a significant difference in the recovery of testosterone levels between patients aged ≥71 years and those aged <71 years at the start of HT (p=0.002), and between those who had been on HT for ≥34 months and those for <34 months (p=0.031). In both univariate and multivariate analyses, age at initiation of HT and duration of HT contributed to the recovery of testosterone levels. CONCLUSION: The rate of recovery of testosterone levels after long-term (median 34.3 months) HT was lower in patients who were older than 71 years at the start of HT.

Surgical proficiency in laparoscopic radical cystectomy with extracorporeal urinary diversion and its adequacy for the execution of robot-assisted radical cystectomy with intracorporeal urinary diversion.

INTRODUCTION: The number of facilities adopting intracorporeal urinary diversion (ICUD) using robots instead of extracorporeal urinary diversion (ECUD) is increasing. However, guidance on how to introduce robot-assisted radical cystectomy (RARC) + ICUD in each urological institute remains unclear. This study aimed to verify the feasibility of the transition from laparoscopic radical cystectomy (LRC) + ECUD to RARC + ICUD. METHODS: We retrospectively analyzed 26 consecutive patients who underwent ICUD with an ileal conduit after RARC between 2018 and 2020 (RARC + ICUD early group). We then compared these patients with 26 consecutive patients who underwent ECUD with an ileal conduit after LRC between 2012 and 2019 (LRC + ECUD late group) at Yokohama City University Hospital. RESULTS: In the RARC + ICUD early group compared with the LRC + ECUD late group, the median total operation time was 516 versus 532.5 min (P = .217); time to cystectomy, 191 versus 206.5 min (P = .234); time of urinary diversion with an ileal conduit, 198 versus 220 min (P = .016); postoperative maximum C-reactive protein levels, 6.98 versus 12.46 mg/L (P = .001); number of days to oral intake, 3 versus 5 days (P = .003); length of hospital stay, 17 versus 32 days (P < .001). The postoperative complication rates (within 90 days) were 23.1% and 42.3% in the RARC + ICUD early and LRC + ECUD late groups, respectively (P = .237). Clavien-Dindo classification ≥3 was noted in 1 and 4 patients in the RARC + ICUD early and LRC + ECUD late groups, respectively (P = .350). CONCLUSION: Regarding perioperative outcomes, the RARC + ICUD early group was not inferior to the LRC + ECUD late group. This study suggests the feasibility of a transition from LRC + ECUD to RARC + ICUD.

Prognostic value of automated bone scan index for predicting overall survival among bone metastatic castration resistant prostate cancer patients treated with radium-223.

Introduction: The objective of this study was to evaluate automated bone scan index (aBSI) as a prognostic biomarker for overall survival (OS) in bone-metastatic, castration-resistant prostate cancer (mCRPC) patients treated with radium-223 (Ra-223). Materials and methods: We identified 42 men treated with Ra-223 for mCRPC. We investigated aBSI as an independent prognostic factor by multivariate analysis. Moreover, we evaluated the prognostic value of the aBSI after 12 weeks after the first cycle of Ra-223 administration and aBSI change from baseline to after 12 weeks (ΔBSI). Results: Median baseline PSA and aBSI were 42.8 ng/mL and 1.5%, respectively. Median OS was 20.7 months. Multivariate analysis showed that baseline aBSI was a significant prognostic factor for OS. The aBSI at 12 weeks after first Ra-223 administration also exhibited significant prognostic value for OS, while we found no evidence of prognostic value for ΔBSI. Conclusions: Baseline aBSI may be a significant prognostic factor for OS in bone-metastatic CRPC patients treated with Ra-223.

Correlation between Automated Bone Scan Index Change after Cabazitaxel and Survival among Men with Castration-Resistant Prostate Cancer.

BACKGROUND: Automated bone scan index (aBSI) change (ΔBSI) after treatment and survival in men with prostate cancer remains unclear. We evaluated the correlation between ΔBSI after cabazitaxel and overall survival (OS) in men with bone metastatic castration-resistant prostate cancer (CRPC). METHODS: We retrospectively enrolled 32 men with bone metastatic CRPC who had received cabazitaxel. The correlation between ΔBSI from baseline to 16 weeks after starting cabazitaxel and OS was analyzed by multivariate analysis. RESULTS: Median age and time to CRPC were 70.7 years and 9.5 months, respectively. The median cycles of docetaxel before cabazitaxel were eight. Ten (31.2%) patients had visceral metastases at baseline. Median baseline prostate-specific antigen (PSA) was 123.0 ng/mL. The median aBSIs at baseline and 16 weeks after cabazitaxel were 3.2 and 4.4%, respectively. Improvements in aBSI and PSA after 16 weeks of cabazitaxel occurred in 7 (21.9%) and 12 patients (37.5%), respectively. There were no correlations between ΔBSI and OS (p = 0.55), but PSA change was significantly correlated with OS (p = 0.03) by multivariate analysis. CONCLUSIONS: This study demonstrated that ΔBSI from baseline to16 weeks after starting cabazitaxel was not correlated with OS among men with bone metastatic CRPC. Further prospective studies may be warranted to confirm the limited utility of aBSI in this setting.

Prediction of Time to Castration-Resistant Prostate Cancer Using Low-Molecular-Weight Protein Tyrosine Phosphatase Expression for Men with Metastatic Hormone-Naïve Prostate Cancer.

INTRODUCTION: Low-molecular-weight protein tyrosine phosphatase (LMW-PTP) expression affects carcinogenesis in various cancers and has been associated with determining the overall survival among men with metastatic hormone-naïve prostate cancer (mHNPC). In this study, we analyzed the value of LMWPTP for prediction of time to castration-resistant prostate cancer (CRPC) for men with mHNPC. MATERIALS AND METHODS: We retrospectively enrolled 45 men with mHNPC who were diagnosed from 2003 to 2009. All patients had received androgen deprivation therapy as first-line treatment. Prostate cancer tissues (pre-treatment needle biopsies) were immunohistochemically stained for LMW-PTP. Multivariate analyses (Cox proportional hazard model) were used to correlate baseline clinical factors of age, prostate-specific antigen (PSA), Gleason scores, T stage, N stage, extent of disease on bone scan (EOD), LMW-PTP expression and time to CRPC. Continuous variables were classified as dichotomous. RESULTS: Median age and PSA were 70.0 years and 87.8 ng/mL respectively. Median time to CRPC was 40.2 months. Median time to CRPC was significantly shorter in the high LMW-PTP group (14.8 months) than that in the low LMW-PTP group (86.3 months, p < 0.01). In multivariate analysis, age ≥70 years and high LMW-PTP expression were significant predictors of time to CRPC.

Prognostic value of an automated bone scan index for men with metastatic castration-resistant prostate cancer treated with cabazitaxel.

BACKGROUND: A computer-assisted diagnostic system for analyzing bone scans (BONENAVI) calculates the automated bone scan index (aBSI). Here we evaluated the aBSI as a prognostic imaging biomarker for men with metastatic castration-resistant prostate cancer (mCRPC) treated with cabazitaxel. METHODS: We retrospectively analyzed 48 patients who received cabazitaxel for mCRPC and evaluated the ability of the aBSI to predict overall survival (OS). The Cox proportional hazards model was used to investigate the associations between baseline aBSI at cabazitaxel treatment and OS with the clinical variables as follows: age, number of cycles of docetaxel, serum prostate-specific antigen, hemoglobin (Hb), lactate dehydrogenase (LDH), and alkaline phosphatase. We determined the C-index to evaluate the discriminatory ability of our models when we included or excluded the aBSI from the analyses. RESULTS: The median OS after cabazitaxel treatment was 10.0 months, and patients with aBSI ≤1% achieved significantly longer OS compared with patients with aBSI ≥1%. Multivariate analysis showed that age, Hb, LDH, and aBSI were independent prognostic factors of OS. Adding aBSI to the base model increased the C-index from 0.78 to 0.80. CONCLUSIONS: The aBSI may serve as a useful imaging biomarker for predicting OS among men with mCRPC treated with cabazitaxel. Prospective studies are required to establish the value of aBSI as prognostic imaging biomarker.

Efficacy and safety of 3-month dosing regimen of degarelix in Japanese subjects with prostate cancer: A phase III study.

Non-inferiority in the cumulative castration rate of the 3-month formulation of degarelix compared with the 3-month formulation of goserelin was evaluated in subjects with prostate cancer. A phase III, open-label, parallel-arm study was carried out. An initial dose of 240 mg degarelix or 3.6 mg goserelin was given s.c.; after day 28, a maintenance dose of 480 mg degarelix or 10.8 mg goserelin was given once every 84 days. Non-inferiority in castration rate and safety of degarelix to goserelin were evaluated. The primary end-point was the cumulative castration rate from day 28 to day 364 and the non-inferiority margin was set to be 10%. A total of 234 subjects with prostate cancer were randomized to the degarelix group (n = 117) and the goserelin group (n = 117). The cumulative castration rate was 95.1% in the degarelix group and 100.0% in the goserelin group. As there were no events in the goserelin group, an additional analysis was carried out using 95% confidence intervals of the difference in the proportion of subjects with castration. Analyses indicated the non-inferiority of the 3-month formulation of degarelix to goserelin. Degarelix showed more rapid decreases in testosterone, luteinizing hormone, follicle stimulating hormone, and prostate-specific antigen levels compared with goserelin. The most common adverse events in the degarelix group were injection site reactions. Non-inferiority of the 3-month formulation of degarelix to goserelin was shown for testosterone suppression. The 3-month formulation of degarelix was also found to be tolerated as an androgen deprivation therapy for patients with prostate cancer. This trial was registered with ClinicalTrials.gov (identifier NCT01964170).

Neutrophil-to-Lymphocyte Ratio Predicts Prognosis in Castration-Resistant Prostate Cancer Patients Who Received Cabazitaxel Chemotherapy.

INTRODUCTION AND OBJECTIVES: An elevated neutrophil-to-lymphocyte ratio (NLR) has been suggested to be associated with a poor prognosis in several cancers. We evaluated the utility of an elevated NLR as a biomarker to predict the prognosis of metastatic castration-resistant prostate cancer (mCRPC) patients treated with cabazitaxel (CBZ). METHODS: We analyzed 47 patients who received CBZ chemotherapy for mCRPC in our institutions. The NLR was calculated using the neutrophil and lymphocyte counts before CBZ chemotherapy. We determined the NLR cut-off value based on the sensitivity and specificity levels derived from area under the receiver operator characteristic curves for death. A multivariate analysis was performed to investigate the association between the NLR and the prognosis. RESULTS: The median overall survival (OS) after CBZ was 10.0 months (range: 6.3-13.2). The median OS was shorter in patients with a high NLR (≥3.83) than in those with a low NLR (<3.83) (5.8 versus 13.2 months, p = 0.018). In the multivariate analysis, the NLR, patient age, and lymph node (LN) metastasis were independent predictors of the OS (hazard ratio 3.01, p = 0.030; hazard ratio 3.10, p = 0.029; hazard ratio 12.38, p = 0.001, resp.). CONCLUSIONS: NLR might be a useful prognostic biomarker in mCRPC patients treated with CBZ.

Prediction of Time to Castration-Resistant Prostate Cancer Using Bone Scan Index in Men with Metastatic Hormone-Sensitive Prostate Cancer.

INTRODUCTION: We evaluated bone scan index (BSI) as a predictive biomarker for time to castration-resistant prostate cancer (CRPC) in patients with metastatic hormone-sensitive prostate cancer (mHSPC). MATERIALS AND METHODS: We identified 85 consecutive mHSPC patients treated with first-line androgen deprivation therapy. We analyzed the correlations between time to CRPC and clinicopathological characteristics, including age, prostate-specific antigen (PSA) level, Gleason score, clinical TNM stage, hemoglobin, lactate dehydrogenase, C-reactive protein, and BSI. RESULTS: The median BSI was 2.7%. Progression to CRPC occurred in 55 (64.7%) patients and the median time to CRPC was 12.9 months. In multivariate analysis, 3 significant risk factors for time to CRPC were identified: age (>73 vs. ≤73 years; hazard ratio [HR] 0.53), p = 0.038, PSA level (>270 vs. ≤270 ng/mL; HR 0.53, p = 0.038), and BSI (>2.7 vs. ≤2.7%; HR 2.97, p < 0.001). CONCLUSION: Age, PSA level, and BSI were found to be significant predictive factors for time to CRPC in patients with mHSPC.

Low-molecular-weight protein tyrosine phosphatase expression as a prognostic factor for men with metastatic hormone-naïve prostate cancer.

OBJECTIVES: Recent studies have demonstrated that up-front docetaxel combined with androgen deprivation therapy (ADT) prolongs survival in some patients with metastatic hormone-naïve prostate cancer (mHNPC). However, new biomarkers for selecting personalized treatment strategies for mHNPC are warranted. We evaluated the value of low-molecular-weight protein tyrosine phosphatase (LMW-PTP) expression as a prognosticator in men with mHNPC. METHODS AND MATERIALS: A total of 48 men with mHNPC diagnosed from 2003 to 2009 were enrolled in this study. Prostate cancer tissues obtained by needle biopsies were immunohistochemically stained for LMW-PTP. Correlations between LMW-PTP expression and clinicopathological characteristics were then assessed. RESULTS: At the time of analysis, 29 (60.4%) patients were alive, whereas 15 (31.3%) and 4 (8.3%) died of prostate cancer and nonprostate cancer, respectively. Of these, 29 (60.4%) had low LMW-PTP expression and 19 (39.6%) had high expression. Median overall survival (OS) for patients with high LMW-PTP expression was not reached and that for patients with low LMW-PTP expression was 23.8 months. High LMW-PTP expression was significantly correlated with a shorter OS compared with low LMW-PTP expression (P = 0.01). Moreover, multivariate analysis showed that Gleason score (≥8 vs.≤7; HR = 5.8, 95% CI: 1.3-26.5, P = 0.02) and LMW-PTP expression (high vs. low; HR = 2.7, 95% CI: 1.0-7.2, P = 0.04) were independent prognostic factors for OS. CONCLUSIONS: LMW-PTP is a potential biomarker to predict OS in patients with mHNPC.

Modified C index: Novel predictor of postoperative renal functional loss of laparoscopic partial nephrectomy.

INTRODUCTION: We aimed to develop a scoring system to quantify the distance between the renal hilum and renal tumour, termed the modified C index (m-CI), and to predict renal functional loss (RFL) following laparoscopic partial nephrectomy (LPN). METHODS: The m-CI was measured by using computed tomography in 113 patients who underwent LPN between May 2003 and June 2014. The RFL following LPN was calculated by examining the estimated glomerular filtration rate (eGFR) and radioisotope renography one year postoperatively. The Pythagorean theorem was used to calculate the distance from the tumour centre to the renal hilum. The distance was divided by the tumour radius to obtain the m-CI. The correlation between the m-CI and the postoperative RFL were evaluated using Pearson's coefficient values. Multivariate logistic regression models were used to assess the potential predictive factors of RFL following LPN. The correlation between the m-CI and the operative time, ischemia time, and blood loss during LPN were also evaluated by the unpaired t-test. RESULTS: Pearson's coefficient values between the postoperative RFL and the m-CI and C index were 0.294 and 0.173, respectively. In the multivariate analysis, the resected volume (p=0.031) and m-CI (p=0.036) significantly correlated with the postoperative RFL following LPN. The operative time (p<0.001), ischemia time (p=0.028), and blood loss (p=0.047) during LPN was significantly longer and larger, respectively, in the group with shorter m-CI (≤4.5) than in the group with the longer m-CI (>4.5). CONCLUSIONS: The present study demonstrates that the m-CI can predict RFL following LPN, as well as the surgical difficulty.

Measurement of serum isoform [-2]proPSA derivatives shows superior accuracy to magnetic resonance imaging in the diagnosis of prostate cancer in patients with a total prostate-specific antigen level of 2-10 ng/ml.

OBJECTIVE: More accurate diagnostic procedures for prostate cancer are needed to avoid unnecessary biopsy due to the low specificity of prostate-specific antigen (PSA). Recent studies showed that the percentage of serum isoform [-2]proPSA (p2PSA) to free PSA (%p2PSA), the Prostate Health Index (PHI) and magnetic resonance imaging (MRI) were more accurate than PSA. The aim of this study was to test the accuracy of %p2PSA, PHI and MRI in discriminating patients with and without prostate cancer. MATERIALS AND METHODS: The subjects were 50 consecutive men with a PSA level of 2.0-10.0 ng/ml, who underwent prostate biopsy from October 2012 to July 2014. These patients underwent multiparametric MRI before biopsy, and their serum samples were measured for PSA, free PSA and p2PSA. The sensitivity, specificity and accuracy of PHI, %p2PSA and MRI were compared with PSA in the diagnosis of biopsy-confirmed prostate cancer. RESULTS: In a univariate analysis, %p2PSA [area under the curve (AUC): 0.811] and PHI (AUC 0.795) were more accurate than MRI (AUC: 0.583) and PSA (AUC: 0.554) for prostate cancer detection. At 60% sensitivity, the specificity of PHI (76.5%) was higher than that of MRI (52.9%). For significant cancer detection, %p2PSA (AUC: 0.745), PHI (AUC: 0.791) and MRI (AUC: 0.739) were marginally more accurate than PSA (AUC: 0.696). At 85% sensitivity, the specificity of MRI (62.1%) was higher than that of PHI (34.5%). CONCLUSION: PHI and %p2PSA can be used for screening the general population and MRI can be used for detection of significant cancer in patients suspected, from screening tests, of having prostate cancer.

One-month assessment of renal cell carcinoma treated by everolimus using FDG PET/CT predicts progression-free and overall survival.

PURPOSE: We evaluated 18F-2-fluoro-2-deoxyglucose positron emission tomography/computed tomography (FDG PET/CT) results as outcome predictors for patients with metastatic renal cell carcinoma (RCC) treated by everolimus (EVL), an inhibitor of mammalian target of rapamycin. METHODS: We retrospectively reviewed 30 patients who were treated with EVL for metastatic RCC between May 2010 and March 2015, by evaluating their FDG PET/CT result before and 1 month after starting EVL treatment. We examined the relationships between each patient's maximum standardized uptake value (max SUVmax) assessed by FDG PET/CT on progression-free survival (PFS) and overall survival (OS). RESULTS: Median PFS for all 30 patients was 3.77 months (range 0.72-24.56 months) and median OS after EVL treatment of all 30 patients was 11.67 months (range 1.0-62.98 months). Enrolled patients were divided into two groups by max SUVmax prior to EVL (median = 7.6) and at 1 month after EVL treatment (median = 5.7). PFS were significantly shorter in higher max SUVmax prior to EVL (<7.6, PFS 7.8 vs 3.5 months, log-rank P = 0.017) and at 1 month after EVL (<5.7, PFS 10.6 vs 2.7 months, log-rank P = 0.002) than lower max SUVmax. OS were also significantly shorter in higher max SUVmax prior to EVL (<7.6, OS 18.1 vs 7.5 months, log-rank P = 0.010) and at 1 month after EVL (<5.7, OS 17.2 vs 7.5 months, log-rank P = 0.009) than lower max SUVmax. Multivariate Cox hazard regression analysis indicated that max SUVmax at 1 month after EVL is an independent predictor of both PFS and OS in patients treated with EVL although univariate regression analysis showed max SUVmax before EVL is a possible predictor. CONCLUSIONS: Max SUVmax assessed by FDG PET/CT prior to EVL and at 1 month after EVL treatment can accurately predict PFS and can guide decisions on whether to continue or change treatments for patients with EVL-treated RCC who suffer from adverse events.

Prognostic Value of Automated Bone Scan Index in Men With Metastatic Castration-resistant Prostate Cancer Treated With Enzalutamide or Abiraterone Acetate.

PURPOSE: Bone scan index (BSI) is an objective tool for quantifying bone metastasis load. We assessed its prognostic usefulness in patients with metastatic castration-resistant prostate cancer (CRPC) treated with enzalutamide (ENZ) or abiraterone acetate (AA). MATERIALS AND METHODS: We analyzed 40 patients who received ENZ or AA treatment (ENZ/AA) for metastatic CRPC. The Cox proportional hazards model and a C-index were used to investigate associations between overall survival (OS) and BSI, and patient age, prostate-specific antigen, time to CRPC, previous docetaxel use, and pain. RESULTS: Median OS after ENZ/AA was 17.8 months. All patient deaths (n = 19; 47.5%) were from prostate cancer. In multivariate analysis, decreased BSI was an independent predictor for longer OS (hazard ratio, 8.97; P = .011). Inclusion of BSI improved the C-index from 0.721 to 0.792 in predicting OS after ENZ/AA. CONCLUSIONS: Decreased BSI after ENZ/AA independently predicts longer OS.

[MUCINOUS TUBULAR AND SPINDLE CELL CARCINOMA SUCCESFULLY CONTROLED BY TEMISIROLIMUS: A CASE REPORT].

A 45-year-old woman with dyspnea and appetite and weight loss was admitted to our hospital. Computed tomography (CT) revealed a right hypovascular renal tumor with tumor thrombus in the inferior vena cava and metastases in the liver, stomach, and left kidney. The renal tumor was diagnosed as a mucinous tubular and spindle cell carcinoma (MTSCC) by pathological examination of a percutaneous needle biopsy specimen. She was treated with temsirolimus (25 mg per week). Five weeks after initiation of this treatment, her liver metastases had clearly decreased in size and her appetite had been restored. However, progressive disease was diagnosed by CT scan revealing expansion of tumor thrombus after 7 weeks, prompting a switch in treatment to axitinib. Approximately 6 months after the diagnosis, she died of cancer. MTSCC is considered to have relative good prognosis, however, many cases with poor prognoses have been reported recently. Our experience with this patient suggests that temsirolimus may be effective treatment for metastatic MTSCC.

[A CASE OF XANTHOGRANULOMATOUS PYELONEPHRITIS ASSOCIATED WITH CHROMOPHOBE RENAL CELL CARCINOMA].

Xanthogranulomatous pyelonephritis (XGP) is a type of chronic suppurative renal inflammation. We present an extremely rare case of XGP concomitant with chromophobe renal cell carcinoma (RCC). A-39-year-old woman presented with transient fever and left lower abdominal pain during steroid pulse therapy for thyroid eye disease. Imaging studies including contrast-enhanced computed tomography, magnetic resonance imaging, and doppler ultrasonography, showed a 40 mm unusual mass lesion in the upper pole of the left kidney, and we could not rule out the possibility of malignancy.A left open partial nephrectomy for the renal mass was performed. Pathological examination revealed a 5 mm chromophobe RCC located beside a 30 mm XGP. The patient presented a favorable course without inflammatory episodes or tumor recurrence during the 9-month follow-up. This is the first case report of the coexistent XGP and chromophobe RCC.

The impact of gender difference on operative time in laparoscopic partial nephrectomy for T1 renal tumor and the utility of retroperitoneal fat thickness as a predictor of operative time.

BACKGROUND: To investigate the impact of biological gender on operative parameters, especially operative time, in laparoscopic partial nephrectomy (LPN) for T1 renal tumor. METHODS: One hundred and eleven (28 female and 83 male) patients and 64 (20 female and 44 male) patients with renal tumors suspected to be RCC cT1aN0M0 who underwent retroperitoneal and transperitoneal LPN, respectively, were analyzed. The influence of sex on operative factors including retroperitoneal fat tissue thickness, determined on CT, was analyzed. The correlation between operative time and gender was evaluated by unpaired t-test and linear logistic regression model. RESULTS: In both retroperitoneal and transperitoneal LPN, the retroperitoneal fat tissue thickness was greater in men than in women. In retroperitoneal LPN, the operative time was significantly longer in men than in women. In contrast, in transperitoneal LPN, no gender difference was observed in regard to the operative time. In retroperitoneal LPN, linear logistic regression assessment showed that gender, retroperitoneal fat tissue thickness, and tumor size were significantly associated with operative time. Coefficient of determination of the prediction model was 0.317. CONCLUSIONS: The operative time of retroperitoneal LPN is significantly correlated with gender, maximum tumor diameter, and retroperitoneal fat tissue thickness. We have developed a prediction model for the operative time of retroperitoneal LPN based on preoperative parameters. Interestingly, in transperitoneal LPN, a gender difference in operative time was not apparent, and also predicting operative time might be difficult.