Mode instability in ytterbium-doped non-circular fibers

We present a theoretical study of transverse mode instability (TMI) in non-circular ytterbium-doped fibers including the rectangular core in a circular or D-shaped cladding. The D-shaped cladding is found efficient to suppress the TMI thanks to better heat dissipation, as compared to the circular cladding. However, the rectangular core does not suppress the TMI despite its better heat dissipation than a circular core counterpart. Although the temperature built in the rectangular core decreases with an increasing aspect ratio of the rectangular core, the low temperature does not benefit the TMI suppression. Instead, the TMI becomes stronger than its circular core counterpart. Our study reveals that the power coupling between two involved modes and gain saturation effect play a significant role in influencing the TMI. The power coupling strength is associated with the frequency offset between two modes, and it grows with an increasing aspect ratio of rectangular cores, suggesting the longer axis of rectangular core promotes the TMI.

Prognostic Factors for Survival of Patients With Synchronous or Metachronous Brain Metastasis of Renal Cell Carcinoma

INTRODUCTION

We evaluated the oncological outcomes of synchronous or metachronous brain metastasis (BM) of metastatic renal cell carcinoma (RCC) according to clinicopathologic factors.

PATIENTS AND METHODS

Patients with metastatic RCC (n = 93) with synchronous and metachronous BM were retrospectively identified. We analyzed patients and tumor characteristics, treatment methods, prognostic factors, BM progression, and overall survival (OS).

RESULTS

Seventy-six patients (81.7%) received local therapy (stereotactic radiosurgery [60.2%], radiation therapy [22.6%], and neurosurgery [10.8%]), and 54 patients (58.1%) were treated with systemic medical therapy. In multivariable analysis, poor Memorial Sloan-Kettering Cancer Center (MSKCC) risk (hazard ratio [HR] 3.672; 95% confidence interval [CI], 1.441-9.36; P = .0064), sarcomatoid component (HR 4.264; 95% CI, 2.062-8.820; P = .0001), and multiple BMs (HR 2.838; 95% CI, 1.690-4.767; P = .0001) were prognostic indicators of a poorer OS outcome. Local (HR 0.436; 95% CI, 0.237-0.802; P = .0076) and systemic treatment (HR 0.322; 95% CI, 0.190-0.548; P < .0001) were independent factors for a better OS. Although OS from initial RCC diagnosis in patients with metachronous BM was better than that for patients with synchronous BM, there were no differences found between synchronous and metachronous patients in terms of BM progression and OS after the diagnosis of BM.

CONCLUSIONS

Poor MSKCC risk, sarcomatoid component of histology, and multiple BMs are prognostic indicators for poor OS in patients with BM from metastatic RCC. Systemic and/or local treatment improves the OS. Because the type of BM, synchronous or metachronous, does not influence BM progression or the OS outcome, routine evaluation for BM is not recommended.

Is suspicious upstaging on multiparametric magnetic resonance imaging useful in improving the reliability of Prostate Cancer Research International Active Surveillance (PRIAS) criteria? Use of the K-CaP registry

BACKGROUND AND OBJECTIVE

To evaluate the clinical effects of suspicious upstaging on multiparametric magnetic resonance imaging (mpMRI) for improving the quality of Prostate Cancer Research International Active Surveillance (PRIAS) criteria.

MATERIAL AND METHODS

A total of 363 patients with low-risk prostate cancer (PCa) were selected from the K-CaP registry (the multicenter Korean PCa Database). Patients were divided into 2 groups according to the results of mpMRI (with or without suspicious upstaging). The variables for predicting significant PCa, defined as locally advanced PCa, Gleason score≥7, or tumor volume>0.5cc or all of these, and adverse PCa, defined as locally advanced PCa, Gleason score≥7 (4+3), or tumor volume>2.5cc or all of these, were assessed.

RESULTS

The mpMRI led to "suspicious" upstaging in 56 patients (15.4%). Significant PCa (98.2% vs. 74.6%, P<0.001) and adverse PCa (85.7% vs. 32.6%, P<0.001) were more common in patients with suspicious upstaging. The sensitivity/specificity of mpMRI for significant PCa and adverse PCa were 25.4%/98.2% and 32.4%/96.3%, respectively. On multivariate analyses, suspicious upstaging on mpMRI (odds ratio: 15.82, P = 0.007) was a predictor for significant PCa in addition to PRIAS criteria and age at diagnosis. In addition, suspicious upstaging on mpMRI (odds ratio: 11.11, P<0.001) was a significant predictor for adverse PCa in addition to PRIAS criteria, age at diagnosis, and body mass index.

CONCLUSION

Along with the PRIAS criteria, suspicious upstaging on mpMRI is a potent diagnostic tool for distinguishing patients suitable for active surveillance among patients with low-risk PCa.

Comparison of outcomes between trimodal therapy and radical cystectomy in muscle-invasive bladder cancer: a propensity score matching analysis

Although radical cystectomy (RC) is considered as the standard therapy for muscle-invasive bladder cancer (MIBC), trimodal therapy (TMT) combining transurethral resection of the tumor with radiotherapy and chemotherapy is increasingly recommended as an alternative approach for bladder preservation. In the absence of randomized trials, we compared the clinical outcomes between RC and TMT using propensity score matching with 50 patients in the RC arm and 29 patients in the TMT arm. With respective median follow-up periods of 23 and 32 months for the RC and TMT groups, 5-year distant metastasis-free survival (58% vs. 67%), overall survival (56% vs. 57%), and cancer-specific survival (69% vs. 63%) rates between the RC and TMT groups, respectively, were similar. However, the 5-year local recurrence-free survival was significantly better in the RC group than in the TMT group (74% vs. 35%). Following TMT, acute grade 3 hematological (n = 2) and late grade 3 genitourinary (n = 1) toxicities were reported. These findings demonstrated that oncological outcomes of TMT were comparable with those of RC, except for poorer local control. Large-scale, randomized trials are warranted to confirm the findings of the present retrospective comparison and to guide toward best treatment options.

Preserving Renal Function through Partial Nephrectomy Depends on Tumor Complexity in T1b Renal Tumors

This study aimed to determine patients with T1b renal cell carcinoma (RCC) who could benefit from partial nephrectomy (PN) and method to identify them preoperatively using nephrometry score (NS). From a total of 483 radical nephrectomy (RN)-treated patients and 40 PN-treated patients who received treatment for T1b RCC between 1995 and 2010, 120 patients identified through 1:2 propensity-score matching were included for analysis. Probability of chronic kidney disease (CKD) until postoperative 5-years was calculated and regressed with respect to the surgical method and NS. Median follow-up was 106 months. CKD-probability at 5-years was 40.7% and 13.5% after radical and PN, respectively (P = 0.005). While PN was associated with lower risk of CKD regardless of age, comorbidity, preoperative estimated renal function, the effect was observed only among patients with NS ≤ 8 (P < 0.001) but not in patients with NS ≥ 9 (P = 0.746). Percent operated-kidney volume reduction and ischemia time were similar between the patients with NS ≥ 9 and ≤ 8. In the stratified Cox regression accounting for the interaction observed between the surgical method and the NS, PN reduced CKD-risk only in patients with NS ≤ 8 (hazard ratio [HR], 0.054; P = 0.005) but not in ≥ 9 (HR, 0.996; P = 0.994). In T1b RCC with NS ≥ 9, the risk of postoperative CKD was not reduced following PN compared to RN. Considering the potential complications of PN, minimally invasive RN could be considered with priority in this subgroup of patients.

Does Ureteral Catheter Insertion Decrease the Risk of Urinary Leakage After Partial Nephrectomy in Patients With Renal Cell Carcinoma?

INTRODUCTION

We aimed to evaluate the impact of preoperative ureteral catheter insertion on urinary leakage after partial nephrectomy (PN) in patients with renal cell carcinoma.

METHODS

We reviewed the data of 893 patients with renal cell carcinoma who underwent PN and divided them according to ureteral catheter placement. The impact of ureteral catheter placement on postoperative urinary leakage was evaluated by using multivariate analysis.

RESULTS

Ureteral catheters were inserted in 397 (44.5%) patients. Patients with ureteral catheter insertion had larger tumors (2.4 vs. 2.6 cm; P = .031); however, the RENAL nephrometry scores were comparable (P = .131). Robotic PN was more common in patients with ureteral catheters (11.1 vs. 53.9%; P < .001). Urinary leakage did not differ according to ureteral catheter placement (3.4 vs. 3.5%; P = .936). Although tumor size (P = .002), ureteral catheter insertion (P < .001), and operative methods (P < .001) were significantly different according to surgeons, the rate of urinary leakage was similar (surgeon A: 4.0%, surgeon B: 4.6%, surgeon C: 1.5%, others: 2.9%; P = .294). In multivariate analysis of preoperative variables, age and RENAL nephrometry scores were associated with urinary leakage. In multivariate analysis of preoperative and intraoperative variables, the operative method, collecting system status, and intraoperative transfusion, but not ureteral catheter insertion, were related to urinary leakage.

CONCLUSIONS

Ureteral catheter insertion does not appear to reduce the risk of urinary leakage after PN, and visibility during PN with meticulous bleeding control is important in preventing urinary leakage after PN.

Risk of Intravesical Recurrence After Ureteroscopic Biopsy for Upper Tract Urothelial Carcinoma: Does the Location Matter?

INTRODUCTION

To investigate whether ureteroscopic biopsy (URS-Bx) for upper tract urothelial carcinoma (UTUC) before radical nephroureterectomy affects intravesical recurrence (IVR).

PATIENTS AND METHODS

Of the 515 patients receiving radical nephroureterectomy for UTUC between 1998 and 2012, 387 patients were included for the analysis. URS-Bx was performed in 69 patients (17.8%). Patients were stratified according to tumor location, and the impact of URS-Bx on IVR was evaluated after adjusting for other clinicopathologic variables.

RESULTS

IVR occurred in 163 patients (42.1%). The postoperative 5-year IVR-free survival was not significantly different according to URS-Bx in the overall patient group (54.0% vs 39.3%, p = 0.056). In patients with renal pelvic tumor, IVR-free probability was lower in patients with URS-Bx than in patients without URS-Bx (39.6% vs 62.2%, p = 0.012), although IVR-free survival in patients with ureteral tumor was equivalent (36.7% vs 45.8%, p = 0.946). In multivariate analysis, previous bladder tumors (hazard ratio [HR], 1.65; p = 0.016) were a significant risk factor for IVR in all patients and ureteral tumor location (HR, 1.35; p = 0.071) was associated with IVR, although statistical significance was not achieved. In patients with renal pelvic tumor, URS-Bx HR, 1.98; p = 0.020 was the only risk factor for IVR. However, URS-Bx was not associated with IVR in patients with ureteral tumor, although previous bladder tumor HR, 1.74; p = 0.028 was a risk factor for IVR.

CONCLUSION

URS-Bx is a significant risk factor for IVR in patients with renal pelvic tumor and should be performed after sufficient consideration in these patients if other examinations are uncertain.

Record power, ultra-broadband supercontinuum source based on highly GeO2 doped silica fiber

We demonstrate highly germania doped fibers for mid-infrared supercontinuum generation. Experiments ensure a highest output power of 1.44 W for a broadest spectrum from 700 nm to 3200 nm and 6.4 W for 800 nm to 2700 nm from these fibers, while being pumped by a broadband Erbium-Ytterbium doped fiber based master oscillator power amplifier. The effect of repetition frequency of pump source and length of germania-doped fiber has also been investigated. Further, germania doped fiber has been pumped by conventional supercontinuum source based on silica photonic crystal fiber supercontinuum source. At low power, a considerable broadening of 200-300 nm was observed. Further broadening of spectrum was limited due to limited power of pump source. Our investigations reveal the unexploited potential of germania doped fiber for mid-infrared supercontinuum generation. These measurements ensure the potential of germania based photonic crystal fiber or a step-index fiber supercontinuum source for high power ultra-broad band emission being by pumped a 1060 nm or a 1550 nm laser source. To the best of our knowledge, this is the record power, ultra-broadband, and all-fiberized supercontinuum light source based on silica and germania fiber ever demonstrated to the date.

Oncological outcomes of patients with incidental pathological T3a stage small renal cell carcinoma after partial nephrectomy

PURPOSE

This study was designed to evaluate and compare the oncological outcomes of patients with pathological T1a (pT1a) small renal cell carcinomas (RCCs) with those with incidental pathological T3a (pT3a) RCCs who have been treated using partial nephrectomy (PN).

METHODS

We retrospectively evaluated the records of 1367 consecutive patients who underwent PN for small RCCs (≤4 cm) between 1997 and 2014. The curves for recurrence-free, cancer-specific, and overall survival were estimated using the Kaplan-Meier method. Cox regression analysis was used to estimate the prognostic significance of each variable.

RESULTS

Of the 1367 small RCC patients identified, 1324 (96.8 %) had pT1a lesions and 43 (3.2 %) had pT3a lesions. The median ages of the pT1a and pT3a patients were 53.9 and 58.1 years, respectively. Patients received follow-up for a median of 54 months. The 5- and 10-year RFS rates in patients with pT1a and pT3a RCCs were 98.0 and 95.2 %, and 94.4 and 95.2 %, respectively (P = 0.521). None of the patients with recurrent tumors in the pT3a group have died by the time of the writing of this report. A multivariate Cox proportional hazards model showed that tumor size was a significant predictor of RFS and CSS (P < 0.05). However, pT stage (pT3a vs. pT1a) was not a significant predictor of RFS, CSS, or OS (P = 0.104, P = 0.573, and P = 0.441, respectively).

CONCLUSIONS

Our study found that pT3a stage disease following PN for small RCCs (≤4 cm) had similar oncological outcomes to those of pT1a stage.

New drugs in prostate cancer

The standard primary treatment for advanced prostate cancer has been hormonal therapy since the 1940s. However, prostate cancer inevitably progresses to castration-resistant prostate cancer (CRPC) after a median duration of 18 months of androgen deprivation therapy. In patients with CRPC, docetaxel has been regarded as the standard treatment. However, survival advantages of docetaxel over other treatments are slim, and the need for new agents persists. In recent years, novel agents, including abiraterone, enzalutamide, cabazitaxel, radium-223, and sipuleucel-T, have been approved for the treatment of CRPC, and more such agents based on diverse mechanisms are under investigation or evaluation. In this article, the authors reviewed the current literature on recent advances in medical treatment of prostate cancer, especially CRPC. In addition, the authors elaborated on novel drugs for prostate cancer currently undergoing investigation and their mechanisms.