Advanced optical imaging techniques for bladder cancer detection and diagnosis: a systematic review

OBJECTIVES

To systematically assess the current available literature concerning advanced optical imaging methods for the detection and diagnosis of bladder cancer (BCa), focusing particularly on the sensitivity and specificity of these techniques.

METHODS

First a scoping search was performed to identify all available optical techniques for BCa detection and diagnosis. The optical imaging techniques used for detecting BCa are: the Storz professional image enhancement system (IMAGE1 S), narrow-band imaging (NBI), photoacoustic imaging (PAI), autofluorescence imaging (AFI), photodynamic diagnosis (PDD), and scanning fibre endoscopy (SFE). The staging and grading techniques for BCa are: optical coherence tomography (OCT), confocal laser endomicroscopy (CLE), Raman spectroscopy, endocytoscopy, and non-linear optical microscopy (NLO). Then a systematic literature search was conducted using MEDLINE, EMBASE and Web of Science from inception to 21 November 2023. Articles were screened and selected by two independent reviewers. Inclusion criteria were: reporting on both the sensitivity and specificity of a particular technique and comparison to histopathology, and in the case of a detection technique comparison to white light cystoscopy (WLC).

RESULTS

Out of 6707 articles, 189 underwent full-text review, resulting in 52 inclusions. No articles met criteria for IMAGE1 S, PAI, SFE, Raman spectroscopy, and endocytoscopy. All detection techniques showed higher sensitivity than WLC, with NBI leading (87.8-100%). Overall, detection technique specificity was comparable to WLC, with PDD being most specific (23.3-100%). CLE and OCT varied in sensitivity and specificity, with OCT showing higher specificity for BCa diagnosis, notably for carcinoma in situ (97-99%) compared to CLE (62.5-81.3%). NLO demonstrated high sensitivity and specificity (90-97% and 77-100%, respectively) based on limited data from two small ex vivo studies.

CONCLUSIONS

Optical techniques with the most potential are PDD for detecting and OCT for staging and grading BCa. Further research is crucial to validate their integration into routine practice and explore the value of other imaging techniques.

Artificial intelligence assisted patient blood and urine droplet pattern analysis for non-invasive and accurate diagnosis of bladder cancer

Bladder cancer is one of the most common cancer types in the urinary system. Yet, current bladder cancer diagnosis and follow-up techniques are time-consuming, expensive, and invasive. In the clinical practice, the gold standard for diagnosis remains invasive biopsy followed by histopathological analysis. In recent years, costly diagnostic tests involving the use of bladder cancer biomarkers have been developed, however these tests have high false-positive and false-negative rates limiting their reliability. Hence, there is an urgent need for the development of cost-effective, and non-invasive novel diagnosis methods. To address this gap, here we propose a quick, cheap, and reliable diagnostic method. Our approach relies on an artificial intelligence (AI) model to analyze droplet patterns of blood and urine samples obtained from patients and comparing them to cancer-free control subjects. The AI-assisted model in this study uses a deep neural network, a ResNet network, pre-trained on ImageNet datasets. Recognition and classification of complex patterns formed by dried urine or blood droplets under different conditions resulted in cancer diagnosis with a high specificity and sensitivity. Our approach can be systematically applied across droplets, enabling comparisons to reveal shared spatial behaviors and underlying morphological patterns. Our results support the fact that AI-based models have a great potential for non-invasive and accurate diagnosis of malignancies, including bladder cancer.

Proteomics Profiling of Bladder Cancer Tissues from Early to Advanced Stages Reveals NNMT and GALK1 as Biomarkers for Early Detection and Prognosis of BCa

The high recurrence rate and invasive diagnostic and monitoring methods in bladder cancer (BCa) clinical management require the development of new non-invasive molecular tools for early detection, particularly for low-grade and low-stage BCa as well as for risk stratification. By using an in-solution digestion method and label-free data-independent LC-MS/MS coupled with ion mobility, we profiled the BCa tissues from initiation to advanced stages and confidently identified and quantified 1619 proteins (≥2 peptides). A statistically significant difference in abundance (Anova ≤ 0.05) showed 494 proteins. Significant correlation with stage with steady up or down with BCa stages showed 15 proteins. Testing of NNMT, GALK1, and HTRA1 in urine samples showed excellent diagnostic potential for NNMT and GALK1 with AUC of 1.000 (95% CI: 1.000-1.000; p < 0.0001) and 0.801 (95% CI: 0.655-0.947; p < 0.0001), respectively. NNMT and GALK1 also showed very good potential in discriminating non-invasive low-grade from invasive high-grade BCa with AUC of 0.763 (95% CI: 0.606-0.921; p = 0.001) and 0.801 (95% CI: 0.653-0.950; p < 0.0001), respectively. The combination of NNMT and GALK1 increased prognostic accuracy (AUC = 0.813). Our results broaden the range of potential novel candidates for non-invasive BCa diagnosis and prognosis.

Continuous saline bladder irrigation after blue light transurethral resection of bladder tumor increases recurrence-free survival in low- to intermediate-risk non-muscle invasive bladder cancer

OBJECTIVES

To evaluate the efficacy of Continuous Saline Bladder Irrigation (CSBI) after blue light transurethral resection of bladder tumor (TURBT) to prevent recurrence of low- to intermediate-risk Non-Muscle Invasive Bladder Cancer (NMIBC).

PATIENTS AND METHODS

We conducted a retrospective study including patients with low- to intermediate-risk NMIBC who underwent TURBT in two urological centers between January 2017 and December 2018. Each TURBT was performed using blue light after intravesical instillation of hexaminolaevulinic acid. The experimental group included patients who received CSBI while the control group included patients without CSBI. When practice, CSBI was started immediately after the surgery and was interrupted 24 hours thereafter. Low-risk NMIBC had a surveillance while intermediate NMIBC had 8 adjuvant endovesical instillations of Mitomycin. The primary endpoint was bladder tumor recurrence free-survival which was defined as the time between the initial TURBT and the date of TURBT for bladder recurrence.

RESULTS

A total of 167 patients (median age: 71 years) were included: 20% female, 15% low-risk, 85% intermediate-risk NMIBC. CSBI was performed in 95 cases (57%). No complication related to irrigation was reported. Bladder recurrence was observed in 55 cases (32.9%): 22 (23.1%) in the CSBI group vs. 33 (45.8%) in the control group (P=0.002). Multivariate stepwise logistic regression analysis with backward selection revealed that CSBI (HR 0.47 [0.27-0.81]; P=0.006) and MMC (HR 0.55 [0.31-0.95]; P=0.034) were significantly associated with reduced risk of bladder recurrence.

CONCLUSIONS

Continuous saline bladder irrigation reduced the risk of bladder recurrence after blue light TURBT in patients with low- to intermediate-risk NMIBC while being safe. Prospective randomized study is needed to confirm these results.

LEVEL OF EVIDENCE

3.

Biomarkers for Precision Urothelial Carcinoma Diagnosis: Current Approaches and the Application of Single-Cell Technologies

Simple Summary

Urothelial carcinoma (UC) is the most frequently diagnosed cancer of the urinary tract and is ranked the sixth most diagnosed cancer in men worldwide. About 70–75% of newly diagnosed UCs are non-invasive or low grade. Different tests such as urine cytology and cystoscopy are used to detect UC. If abnormal tissue is found during cystoscopy, then a biopsy will be performed. Cytology has low sensitivity for low-grade cancer while cystoscopy is invasive and costly. Detecting UC early improves the chances of treatment success. Therefore, many researchers have painstakingly identified urine biological markers for non-invasive UC diagnosis. In this review, we summarize some of the latest and most promising biological markers (including FDA-approved and investigational markers). We also discuss some new technologies that can aid research efforts in biological marker discovery for early UC detection.

Abstract

Urothelial carcinoma (UC) is the most frequent malignancy of the urinary system and is ranked the sixth most diagnosed cancer in men worldwide. Around 70–75% of newly diagnosed UC manifests as the non-muscle invasive bladder cancer (NMIBC) subtype, which can be treated by a transurethral resection of the tumor. However, patients require life-long monitoring due to its high rate of recurrence. The current gold standard for UC diagnosis, prognosis, and disease surveillance relies on a combination of cytology and cystoscopy, which is invasive, costly, and associated with comorbidities. Hence, there is considerable interest in the development of highly specific and sensitive urinary biomarkers for the non-invasive early detection of UC. In this review, we assess the performance of current diagnostic assays for UC and highlight some of the most promising biomarkers investigated to date. We also highlight some of the recent advances in single-cell technologies that may offer a paradigm shift in the field of UC biomarker discovery and precision diagnostics.

Diagnostic accuracy of photodynamic diagnosis for upper urinary tract urothelial carcinoma: A systematic review and meta-analysis

BACKGROUND

This study aimed to evaluate the effectiveness of photodynamic diagnosis (PDD) for upper urinary tract urothelial carcinoma (UTUC) by performing a meta-analysis.

METHOD

Relevant articles were retrieved from the Cochrane Library, PubMed, and Embase databases. Studies evaluating the accuracy of PDD for the diagnosis of upper UTUC were included. The pooled sensitivity, specificity, and area under the curve (AUC) were calculated by STATA 16.0 at the per-lesion level.

RESULTS

Six studies with 289 lesions were included in this systematic review and meta-analysis. The pooled results showed that PDD can differentiate upper UTUC from benign lesions with a sensitivity of 0.96 (95 % confidence interval: 0.85-0.99) and a specificity of 0.86 (95 % confidence interval: [0.64-0.95]; AUC, 0.97). Compared with white-light ureterorenoscopy, PDD can significantly improve the additional detection rate of UTUC (RR 0.16, 95 % CI 0.07-0.34 P = 0.000).

CONCLUSIONS

PDD is a valid technique that improves the diagnostic accuracy of UTUC compared with standard white-light ureterorenoscopy at the per-lesion level. PDD is a promising endoscopic technique for upper UTUC.

Diagnostic Performance of Confocal Laser Endomicroscopy for the Detection of Bladder Cancer: Systematic Review and Meta-Analysis

OBJECTIVE

To systematically evaluate the diagnostic efficacy of confocal laser endomicroscopy (CLE) in detection of bladder cancer.

METHODS

A systematic literature search on CLE in diagnosing bladder cancer in PubMed, Embase, and the Cochrane Library databases was performed. A bivariate meta-regression model was used for meta-analysis to evaluate the pooled diagnostic value of CLE.

RESULTS

A total of 5 eligible studies involving 302 lesions were available for this meta-analysis. In a per-lesion analysis, pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and summary receiver-operating curve (SROC) area under the curve (AUC) of CLE for malignant lesions were 0.90 (95% confidence interval [CI]: 0.85-0.94), 0.72 (95% CI: 0.59-0.82), 3.20 (95% CI: 2.14-4.79), 0.14 (95% CI: 0.09-0.21), 23.27 (95% CI: 11.71-46.25), and 0.91 (95% CI: 0.89-0.94), respectively. For low-grade urothelial carcinomas, pooled sensitivity, specificity, PLR, NLR, DOR, and AUC for CLE were 0.72 (95% CI: 0.57-0.84), 0.87 (95% CI: 0.77-0.93), 5.48 (95% CI: 3.12-9.62), 0.32 (95% CI: 0.20-0.50), 17.19 (95% CI: 8.01-36.89), and 0.85 (95% CI: 0.82-0.88), respectively. For high-grade urothelial carcinomas, pooled sensitivity, specificity, PLR, NLR, DOR, and AUC for CLE were 0.82 (95% CI: 0.62-0.92), 0.84 (95% CI: 0.73-0.91), 4.96 (95% CI: 2.58-9.54), 0.22 (95% CI: 0.09-0.52), 22.49 (95% CI: 5.33-94.85), and 0.89 (95% CI: 0.86-0.91), respectively.

CONCLUSION

CLE is a promising endoscopy technique for real-time tumor grading of bladder cancer.

Label-free grading and staging of urothelial carcinoma through multimodal fibre-probe spectroscopy

Urothelial carcinoma (UC) is the most common bladder tumour. Proper treatment requires tumour resection for diagnosing its grade (aggressiveness) and stage (invasiveness). White-light cystoscopy and histopathological examination are the gold standard procedures for clinical and histopathological diagnostics, respectively. However, cystoscopy is limited in terms of specificity, histology requires long tissue processing, both procedures rely on operator's experience. Multimodal optical spectroscopy can provide a powerful tool for detecting, staging and grading bladder tumours in a fast, reliable and label-free modality. In this study, we collected fluorescence, Raman and reflectance spectra from 50 biopsies obtained from 32 patients undergoing transurethral resection of bladder tumour using a multimodal fibre-probe. Principal component analysis allowed distinguishing normal from pathological tissues, as well as discriminating tumour stages and grades. Each individual spectroscopic technique provided high specificity and sensitivity in classifying all tissues; however, a multimodal approach resulted in a considerable increase in diagnostic accuracy (≥95%), which is of paramount importance for tumour grading and staging. The presented method offers the potential for being applied in cystoscopy and for providing an automated diagnosis of UC at the clinical level, with an improvement with respect to current state-of-the-art procedures.

Toward Automated In Vivo Bladder Tumor Stratification Using Confocal Laser Endomicroscopy

Purpose: Urothelial carcinoma of the bladder (UCB) is the most common urinary cancer. White-light cystoscopy (WLC) forms the corner stone for the diagnosis of UCB. However, histopathological assessment is required for adjuvant treatment selection. Probe-based confocal laser endomicroscopy (pCLE) enables visualization of the microarchitecture of bladder lesions during WLC, which allows for real-time tissue differentiation and grading of UCB. To improve the diagnostic process of UCB, computer-aided classification of pCLE videos of in vivo bladder lesions were evaluated in this study. Materials and Methods: We implemented preprocessing methods to optimize contrast and to reduce striping artifacts in each individual pCLE frame. Subsequently, a semiautomatic frame selection was performed. The selected frames were used to train a feature extractor based on pretrained ImageNet networks. A recurrent neural network, in specific long short-term memory (LSTM), was used to predict the grade of bladder lesions. Differentiation of lesions was performed at two levels, namely (i) healthy and benign vs malignant tissue and (ii) low-grade vs high-grade papillary UCB. A total of 53 patients with 72 lesions were included in this study, resulting in ∼140,000 pCLE frames. Results: The semiautomated frame selection reduced the number of frames to ∼66,500 informative frames. The accuracy for differentiation of (i) healthy and benign vs malignant urothelium was 79% and (ii) high-grade and low-grade papillary UCB was 82%. Conclusions: A feature extractor in combination with LSTM results in proper stratification of pCLE videos of in vivo bladder lesions.

Diagnosis of urothelial carcinoma in situ using blue light cystoscopy and the utility of immunohistochemistry in blue light-positive lesions diagnosed as atypical

Carcinoma in situ (CIS) is difficult to visualize with white light cystoscopy (WLC), whereas blue light cystoscopy (BLC) using photosensitizing agents improves detection rates. We retrospectively reviewed transurethral biopsies of bladder tumors in which both WLC and BLC evaluations were performed (n = 135 samples from 79 patients). Biopsies were classified based on the presence/absence of fluorescence under BLC and the final pathological report (CIS/benign/atypical). Forty-one (30%) cases were diagnosed as CIS; of those, 38 (93%) were BLC(+), including 23 that were WLC(-). Conversely, 51 (38%) lesions were BLC(+) but classified as non-CIS. Eleven BLC(+) cases were diagnosed as "atypical." These cases were anonymized and reviewed by 7 pathologists for concordance and then immunostained for CK20, p53, and Ki-67. Immunohistochemistry results were interpreted as consistent with CIS if there was full-thickness staining of CK20, more than 50% p53-positive cells, and more than 50% Ki-67-positive cells. Review of BLC(+)/atypical cases showed a mean agreement of 79%, and none of the cases showed staining pattern consistent with CIS. Therefore, all 11 cases of BLC(+)/atypical were considered non-CIS for the final analysis. All patients with BLC(+)/atypical lesions had a history of intravesical Bacillus Calmette-Guerin and/or mitomycin. Using final pathology as the reference, sensitivity, specificity, and negative predictive value of BLC were 93% (confidence interval [CI], 80.1%-98.5%), 46% (CI, 35.4%-56.3%), and 94% (CI, 82.5%-97.8%), respectively. The low specificity of BLC leads to BLC(+) lesions with atypical diagnosis. Morphological classification of these lesions is fairly consistent among different pathologists. Immunohistochemistry for p53/CK20/Ki-67 in this setting is only helpful to potentially avoid overcalling CIS.

Optical and Cross-Sectional Imaging Technologies for Bladder Cancer

Optical and cross-sectional imaging plays critical roles in bladder cancer diagnostics. White light cystoscopy remains the cornerstone for the management of non-muscle-invasive bladder cancer. In the last decade, significant technological improvements have been introduced for optical imaging to address the known shortcomings of white light cystoscopy. Enhanced cystoscopy modalities such as blue light cystoscopy and narrowband imaging survey a large area of the urothelium and provide contrast enhancement to detect additional lesions and decrease cancer recurrence. However, higher false-positive rates accompany the gain of sensitivity. Optical biopsy technologies, including confocal laser endomicroscopy and optical coherence tomography, provide cellular resolutions combined with subsurface imaging, thereby enabling optical-based cancer characterization, and may lead to real-time cancer grading and staging. Coupling of fluorescently labeled binding agents with optical imaging devices may translate into high molecular specificity, thus enabling visualization and characterization of biological processes at the molecular level. For cross-sectional imaging, upper urinary tract evaluation and assessment potential extravesical tumor extension and metastases are currently the primary roles, particularly for management of muscle-invasive bladder cancer. Multi-parametric MRI, including dynamic gadolinium-enhanced and diffusion-weighted sequences, has been investigated for primary bladder tumor detection. Ultrasmall superparamagnetic particles of iron oxide (USPIO) are a new class of contrast agents that increased the accuracy of lymph node imaging. Combination of multi-parametric MRI with positron emission tomography is on the horizon to improve accuracy rates for primary tumor diagnostics as well as lymph node evaluation. As these high-resolution optical and cross-sectional technologies emerge and develop, judicious assessment and validation await for their clinical integration toward improving the overall management of bladder cancer.

Optical biopsy of bladder cancer using confocal laser endomicroscopy

OBJECTIVE

Confocal laser endomicroscopy (CLE) is an emerging endoscopic technique that can provide in vivo histopathologic information. It may improve the diagnostic criteria for benign and neoplastic lesions of the bladder. In this study, we reported our experience with utilizing CLE imaging when treating bladder neoplasms, and investigated its diagnostic value with respect to histologic diagnosis.

MATERIALS AND METHODS

Twenty-one patients scheduled for diagnostic cystoscopy or transurethral resection of the bladder tumor were enrolled prospectively. CLE was performed after intravesical fluorescein administration and confocal video sequences were reviewed and analyzed retrospectively. Histopathology served as reference standard for comparison.

RESULTS

Confocal laser endomicroscopy-based classification combined with white light cystoscopy (WLC) images was consistent with histopathology in 17 cases (81.0%). Consensus with histopathological results was found in six cases (85.7%) for low-grade urothelial carcinoma and eight cases (80.0%) for high-grade urothelial carcinoma.

CONCLUSION

Confocal laser endomicroscopy was proved to be a useful technique that could complement white light cystoscopy by providing real-time histopathological information of bladder lesions.

Diagnostic accuracy of optical coherence tomography for bladder cancer: A systematic review and meta-analysis

BACKGROUND

Bladder cancer is the fourth most common malignancy in men and a considerable disease burden globally. Multiple studies have focused on the accuracy of optical coherence tomography for bladder cancer diagnosis; however, the findings are inconsistent. Here, we assessed the accuracy of optical coherence tomography for bladder cancer diagnosis.

METHODS

Embase, PubMed, Medline, Web of Science, and the Cochrane Library database were searched for relevant studies from the earliest date available through March 11, 2019. Studies evaluating the accuracy of optical coherence tomography bladder cancer diagnosis were included. Pooled sensitivity, specificity, and area under the curve values of weighted symmetric summary receiver operating curves, were calculated at the per-lesion level.

RESULTS

Eleven studies, with a total of 1933 lesions, were included in the final analysis. The pooled results indicated that optical coherence tomography can differentiate bladder cancer from benign lesions: sensitivity, 94.9% (95% confidence interval: 92.7%-96.6%); specificity, 84.6% (95% confidence interval: 82.6%-86.4%); area under the curve, 0.97. Moreover, compared with optical coherence tomography alone, combined optical coherence tomography and fluorescence cystoscopy increased the diagnostic accuracy (sensitivity, 94.3% vs. 87.3%; specificity, 89.2% vs. 73.9%). Cross-polarization optical coherence tomography could also distinguish bladder cancer from normal tissue: sensitivity, 92.0% (95% confidence interval: 87.0%-95.6%); specificity, 84.4% (95% confidence interval: 81.7%-86.9%); area under the curve, 0.95.

CONCLUSIONS

Optical coherence tomography can accurately differentiate malignant from benign bladder lesions, particularly when combined with fluorescence cystoscopy.

Meta-analysis of efficacy and safety of continuous saline bladder irrigation compared with intravesical chemotherapy after transurethral resection of bladder tumors

PURPOSE

We performed a meta-analysis to confirm the efficacy and safety of continuous saline bladder irrigation compared with intravesical chemotherapy after transurethral resection for the treatment of non-muscle invasive bladder cancer.

METHODS

Randomized controlled trials of continuous saline bladder irrigation compared with intravesical chemotherapy were searched using MEDLINE, EMBASE, and the Cochrane Controlled Trials Register. The data were evaluated and statistically analyzed using RevMan version 5.3.0.

RESULTS

Four studies including 861 participants which compared continuous saline bladder irrigation with intravesical chemotherapy were considered. One-year recurrence-free survival [odds ratio (OR) = 0.76, 95% CI = 0.55-1.05, p = 0.09]; 2-year recurrence-free survival (OR = 0.94, 95% CI = 0.71-1.25, p = 0.68); the median period to first recurrence (OR = - 1.01, 95% CI = - 2.96 to 0.94, p = 0.31); the number of tumor progression (OR = 0.80, 95% CI = 0.54-1.17, p = 0.25); and the number of recurrence during follow-up (OR = 1.12, 95% CI = 0.84-1.50, p = 0.43) suggested that two methods of postoperative perfusion had no significant differences. In terms of safety, including macrohematuria, frequency of urination and bladder irritation symptoms, continuous saline bladder irrigation showed better tolerance than intravesical chemotherapy.

CONCLUSION

Continuous saline bladder irrigation seems to provide a better balance between prevention of recurrence and local toxicities than intravesical chemotherapy after transurethral resection of bladder tumors.

Recent advances in optical imaging technologies for the detection of bladder cancer

White-light cystoscopy (WLC) is the diagnostic standard for the detection of bladder cancer (BC). However, the detection of small papillary and subtle flat carcinoma in situ lesions is not always possible with WLC. Several adjunctive optical imaging technologies have been developed to improve BC detection and resection. Photodynamic diagnosis, which requires the administering of a photoactive substance, has a higher detection rate than WLC for the detection of BC. Narrow-band imaging provides better visualization of tumors by contrast enhancement between normal mucosa and well-vascularized lesions. A technology called confocal laser endomicroscopy can be used to obtain detailed images of tissue structure. Optical coherence tomography is a high-resolution imaging process that enables noninvasive, real-time, and high-quality tissue images. Several other optical imaging technologies are also being developed to assist with the detection of BC. In this review, we provide an overview of the strengths and weaknesses of these imaging technologies for the detection of BC.

Narrow band imaging-assisted transurethral resection reduces the recurrence risk of non-muscle invasive bladder cancer: A systematic review and meta-analysis

CONTEXT

Compared with white light imaging (WLI) cystoscopy, narrow band imaging (NBI) cystoscopy could increase the visualization and detection of bladder cancer (BC) at the time of transurethral resection (TUR). NBI cystoscopy could increase the detection of BC, but it remains unclear whether narrow band imaging-assisted transurethral resection (NBI-TUR) could reduce the recurrence risk of non-muscle invasive bladder cancer (NMIBC). Several randomized clinical trials (RCTs) have recently tested the efficacy of NBI-TUR for NMIBC.

OBJECTIVE

To perform a systematic review and meta-analysis of RCTs and evaluate the efficacy of NBI-TUR for NMIBC compared with white light imaging-assisted transurethral resection (WLI-TUR). The end point was recurrence risk.

EVIDENCE ACQUISITION

A systematic review of PubMed, Medline, Ovid, Embase, Cochrane and Web of Science was performed in February 2016 and updated in July 2016.

EVIDENCE SYNTHESIS

Overall, six (n = 1084) of 278 trials were included. Three trials performed narrow band imaging-assisted electro-transurethral resection (NBI-ETUR), and two trials performed narrow band imaging-associated bipolar plasma vaporization (NBI-BPV). The last trial performed narrow band imaging-associated holmium laser resection (NBI-HLR). Statistical analysis was performed using Review Manager software (RevMan v.5.3; The Nordic Cochrane Center, Copenhagen, Denmark). The recurrence risk was compared by calculating risk ratios (RRs) with 95% confidence interval (CIs). Risk ratios with 95% CIs were calculated to compare 3-mo, 1-yr, and 2-yr survival rates. NBI-TUR was associated with improvements in the 3-mo recurrence risk (RR: 0.39; 95% CI, 0.26-0.60; p < 0.0001), 1-yr recurrence risk (RR: 0.52; 95% CI, 0.40-0.67; p < 0.00001) and 2-yr recurrence risk (RR: 0.60; 95% CI, 0.42-0.85; p = 0.004) compared with WLI-TUR.

CONCLUSIONS

Compared with WLI-TUR, NBI-TUR can reduce the recurrence risk of NMIBC. The results of this review will facilitate the appropriate application of NBI in NMIBC.

Confocal laser endomicroscopy of bladder and upper tract urothelial carcinoma: a new era of optical diagnosis?

Urothelial carcinoma of the bladder and upper tract pose significant diagnostic and therapeutic challenges. White light endoscopy plays a central role in the management of urothelial carcinoma but has several well-recognized shortcomings. New optical imaging technologies may improve diagnostic accuracy, enhance local cancer control, and better stratify treatment options. Confocal laser endomicroscopy enables dynamic imaging of the cellular structures below the mucosal surface and holds promise in providing real time optical diagnosis and grading of urothelial carcinoma. A variety of imaging probes are available that are compatible with the full spectrum of cystoscopes and ureteroscopes. We review the underlying principles and technique of confocal laser endomicroscopy in the urinary tract, with emphasis on specific application towards urothelial carcinoma. While the available data are largely related to urothelial carcinoma of the bladder, the lessons learned are directly applicable to the upper tract, where the clinical needs are significant. Ongoing efforts to optimize this technology offer an exciting glimpse into future advances in optical imaging and intraoperative image guidance.

Advances in imaging technologies in the evaluation of high-grade bladder cancer

Bladder cancer ranges from a low-grade variant to high-grade disease. Assessment for treatment depends on white light cystoscopy, however because of its limitations there is a need for improved visualization of flat, multifocal, high-grade, and muscle-invasive lesions. Photodynamic diagnosis and narrow-band imaging provide additional contrast enhancement of bladder tumors and have been shown to improve detection rates. Confocal laser endomicroscopy and optical coherence tomography enable real-time, high-resolution, subsurface tissue characterization with spatial resolutions similar to histology. Molecular imaging offers the potential for the combination of optical imaging technologies with cancer-specific molecular agents to improve the specificity of disease detection.

Combined use of fluorescence cystoscopy and cross-polarization OCT for diagnosis of bladder cancer and correlation with immunohistochemical markers

The combined use of fluorescence cystoscopy and cross-polarization optical coherence tomography (CP OCT) with quantitative estimation of the OCT signal was assessed in 92 bladder zones. It demonstrated the diagnostic accuracy in detecting superficial bladder cancer of 93.6%, sensitivity 96.4%, specificity 92.1%, positive predictive value 87% and negative predictive value 97.9%. Quantitative estimation of OCT signal standard deviation in cross-polarization (CP OCT SD index) makes the visual criteria of CP OCT image assessment more objective. The level of CP OCT SD index for diagnosing superficial bladder cancer, including cancer in situ, was 4.32 dB and lower. When tumor is located on a postoperative scar, CP OCT SD index may be higher than the threshold level of 4.32 dB due to strong scattering and depolarization in scar fibrous tissue. A high inverse correlation was found between CP OCT SD index and the level expressed by p63, Ki-67, p53, CD44v6 markers.

Follow-up procedures for non-muscle-invasive bladder cancer: an update

Bladder carcinoma is the most common malignancy of the urinary tract. Approximately 75-85% of patients present with a disease that is confined to the mucosa (stage Ta, carcinoma in situ) or submucosa (stage T1). The stratification of patients to low-, intermediate- and high-risk groups represents the cornerstone for the indication of adjuvant and follow-up treatment. Owing to the high recurrence rate of bladder tumors, a surveillance protocol is recommended to all patients. Currently, the combination of cystoscopy, imaging and urinary cytology represent the follow-up. A systematic review of the recent English literature on follow-up procedures of non-muscle-invasive bladder cancer is performed. The authors review the existing follow-up procedures, with a focus on novel molecular-targeted approaches. At the present time, the additional use and utility of urine-based molecular markers in the follow-up of patients remains unclear and we have to rely on cystoscopic evaluation adapted to risk group classification.

New optical imaging technologies for bladder cancer: considerations and perspectives

PURPOSE

Bladder cancer presents as a spectrum of different diatheses. Accurate assessment for individualized treatment depends on initial diagnostic accuracy. Detection relies on white light cystoscopy accuracy and comprehensiveness. Aside from invasiveness and potential risks, white light cystoscopy shortcomings include difficult flat lesion detection, precise tumor delineation to enable complete resection, inflammation and malignancy differentiation, and grade and stage determination. Each shortcoming depends on surgeon ability and experience with the technology available for visualization and resection. Fluorescence cystoscopy/photodynamic diagnosis, narrow band imaging, confocal laser endomicroscopy and optical coherence tomography address the limitations and have in vivo feasibility. They detect suspicious lesions (photodynamic diagnosis and narrow band imaging) and further characterize lesions (optical coherence tomography and confocal laser endomicroscopy). We analyzed the added value of each technology beyond white light cystoscopy and evaluated their maturity to alter the cancer course.

MATERIALS AND METHODS

Detailed PubMed® searches were done using the terms "fluorescence cystoscopy," "photodynamic diagnosis," "narrow band imaging," "optical coherence tomography" and "confocal laser endomicroscopy" with "optical imaging," "bladder cancer" and "urothelial carcinoma." Diagnostic accuracy reports and all prospective studies were selected for analysis. We explored technological principles, preclinical and clinical evidence supporting nonmuscle invasive bladder cancer detection and characterization, and whether improved sensitivity vs specificity translates into improved correlation of diagnostic accuracy with recurrence and progression. Emerging preclinical technologies with potential application were reviewed.

RESULTS

Photodynamic diagnosis and narrow band imaging improve nonmuscle invasive bladder cancer detection, including carcinoma in situ. Photodynamic diagnosis identifies more papillary lesions than white light cystoscopy, enabling more complete resection and fewer residual tumors. Despite improved treatment current data on photodynamic diagnosis do not support improved high risk diathetic detection and characterization or correlation with disease progression. Prospective recurrence data are lacking on narrow band imaging. Confocal laser endomicroscopy and optical coherence tomography potentially grade and stage lesions but data are lacking on diagnostic accuracy. Several emerging preclinical technologies may enhance the diagnostic capability of endoscopic imaging.

CONCLUSIONS

New optical imaging technologies may improve bladder cancer detection and characterization, and transurethral resection quality. While data on photodynamic diagnosis are strongest, the clinical effectiveness of these technologies is not proven. Prospective studies are needed, particularly of narrow band imaging, confocal laser endomicroscopy and optical coherence tomography. As each technology matures and new ones emerge, cost-effectiveness analysis must be addressed in the context of the various bladder cancer types.

Cross-polarization optical coherence tomography for early bladder-cancer detection: statistical study

The capabilities of cross-polarization optical coherence tomography (CP OCT) for early bladder-cancer detection are assessed in statistical study and compared with the traditional OCT. Unlike the traditional OCT that demonstrates images only in copolarization, CP OCT acquires images in cross-polarization and copolarization simultaneously. 116 patients with localized flat suspicious lesions in the bladder were enrolled, 360 CP OCT images were obtained and analyzed. CP OCT demonstrated sensitivity 93.7% (vs. 81.2%, <0.0001), specificity 84% (vs. 70.0%, <0.001) and accuracy 85.3% (vs. 71.5%, <0.001) in detecting flat malignant bladder lesions, which is significantly better than with the traditional OCT. Higher diagnostic efficacy of CP OCT in detecting early bladder cancer is associated with the ability to detect changes in epithelium and connective tissues.

Dynamic real-time microscopy of the urinary tract using confocal laser endomicroscopy

OBJECTIVES

To develop the diagnostic criteria for benign and neoplastic conditions of the urinary tract using probe-based confocal laser endomicroscopy (pCLE), a new technology for dynamic, in vivo imaging with micron-scale resolution. The suggested diagnostic criteria will formulate a guide for pCLE image interpretation in urology.

METHODS

Patients scheduled for transurethral resection of bladder tumor (TURBT) or nephrectomy were recruited. After white-light cystoscopy (WLC), fluorescein was administered as contrast. Different areas of the urinary tract were imaged with pCLE via direct contact between the confocal probe and the area of interest. Confocal images were subsequently compared with standard hematoxylin and eosin analysis.

RESULTS

pCLE images were collected from 66 participants, including 2 patients who underwent nephrectomy. We identified key features associated with different anatomic landmarks of the urinary tract, including the kidney, ureter, bladder, prostate, and urethra. In vivo pCLE of the bladder demonstrated distinct differences between normal mucosa and neoplastic tissue. Using mosaicing, a post hoc image-processing algorithm, individual image frames were juxtaposed to form wide-angle views to better evaluate tissue microarchitecture.

CONCLUSIONS

In contrast to standard pathologic analysis of fixed tissue with hematoxylin and eosin, pCLE provides real time microscopy of the urinary tract to enable dynamic interrogation of benign and neoplastic tissues in vivo. The diagnostic criteria developed in this study will facilitate adaptation of pCLE for use in conjunction with WLC to expedite diagnosis of urinary tract pathology, particularly bladder cancer.

Comparison of 2.6- and 1.4-mm imaging probes for confocal laser endomicroscopy of the urinary tract

INTRODUCTION

Probe-based confocal laser endomicroscopy (pCLE) is an emerging technology for dynamic, in vivo imaging of the urinary tract with micron-scale resolution. We conducted a comparative analysis of pCLE with a 2.6-mm probe and a 1.4-mm probe that is compatible with flexible endoscopes.

MATERIALS AND METHODS

Sixty-seven patients scheduled for bladder tumor resection were recruited. pCLE imaging was performed using 2.6- and 1.4-mm probes. Image quality with the different probes was examined and further compared with standard histopathology.

RESULTS

Images with the 2.6-mm probe have better resolution of cell morphology. The 1.4-mm probe has a wider field of view and better view of microarchitecture. While image quality with the 2.6-mm probe is superior, the 1.4-mm probe is compatible with flexible cystoscopy and maneuverability is maintained, enabling imaging of areas of the bladder that were previously challenging to access with the larger probe.

CONCLUSIONS

The optical specifications of the 2.6-mm probe are more suitable for distinguishing urinary tract histopathology. Further design optimization to improve resolution and additional validation of the diagnostic accuracy of the smaller probe are needed to help extend application of pCLE for optical biopsy of the upper and lower urinary tract.

Hexyl aminolevulinate fluorescence cystoscopy in bladder cancer

Although bladder cancer occurs frequently, early diagnosis and complete removal of malignant lesions usually lead to good clinical outcomes. In the USA, white light cystoscopy (WLC) is commonly used for bladder cancer diagnosis and guidance of the surgical resection. However, with WLC malignant and precancerous lesions may be missed, resulting in a high rate of disease recurrence. Monitoring for and treating these recurrences carry high direct and indirect costs. Because hexyl aminolevulinate (HAL; 5-ALA-hexylester) fluorescence cystoscopy has greater sensitivity than WLC, especially for detecting early stage lesions, and its use provides more complete resection and lower disease recurrence, it has been recommended in European clinical guidelines. This article reports our own HAL experiences and first time recurrence data, describes how HAL was developed, provides key clinical trial results, and discusses how HAL, which has revolutionized fluorescence cystoscopy and bladder cancer care in Europe, may ultimately revolutionize bladder cancer care in the USA.

Recurrence and progression of disease in non-muscle-invasive bladder cancer: from epidemiology to treatment strategy

CONTEXT

This review focuses on the prediction of recurrence and progression in non-muscle invasive bladder cancer (NMIBC) and the treatments advocated for this disease.

OBJECTIVE

To review the current status of epidemiology, recurrence, and progression of NMIBC and the state-of-the art treatment for this disease.

EVIDENCE ACQUISITION

A literature search in English was performed using PubMed and the guidelines of the European Association of Urology and the American Urological Association. Relevant papers on epidemiology, recurrence, progression, and management of NMIBC were selected. Special attention was given to fluorescent cystoscopy, the new World Health Organisation 2004 classification system for grade, and the role of substaging of T1 NMIBC.

EVIDENCE SYNTHESIS

In NMIBC, approximately 70% of patients present as pTa, 20% as pT1, and 10% with carcinoma in situ (CIS) lesions. Bladder cancer (BCa) is the fifth most frequent type of cancer in western society and the most expensive cancer per patient. Recurrence (in < or = 80% of patients) is the main problem for pTa NMIBC patients, whereas progression (in < or = 45% of patients) is the main threat in pT1 and CIS NMIBC. In a recent European Organisation for Research and Treatment of Cancer analysis, multiplicity, tumour size, and prior recurrence rate are the most important variables for recurrence. Tumour grade, stage, and CIS are the most important variables for progression. Treatment ranges from transurethral resection (TUR) followed by a single chemotherapy instillation in low-risk NMIBC to, sometimes, re-TUR and adjuvant intravesical therapy in intermediate- and high-risk patients to early cystectomy for treatment-refractory high-risk NMIBC.

CONCLUSIONS

NMIBC is a heterogeneous disease with varying therapies, follow-up strategies, and oncologic outcomes for an individual patient.

Single postoperative instillation of gemcitabine in patients with non-muscle-invasive transitional cell carcinoma of the bladder: a randomised, double-blind, placebo-controlled phase III multicentre study

BACKGROUND

Recurrence prophylaxis with intravesical gemcitabine (GEM) was effective and safe in patients with non-muscle-invasive bladder cancer (NMIBC); efficacy as single-shot instillation remains to be proved.

OBJECTIVE

To compare the efficacy of a single GEM instillation versus placebo (PBO) immediately after transurethral resection (TUR) of tumour in patients with histologically confirmed NMIBC (pTa/pT1,G1-3).

DESIGN, SETTING, AND PARTICIPANTS

This was a double-blind, randomised, PBO-controlled study in patients with clinical evidence of primary or recurrent NMIBC (Ta/T1,G1-3). Of 355 patients randomised at 24 urologic centres, 328 underwent TUR and received instillation (92.4%; GEM/PBO: 166/162). In case of nonmalignancy, carcinoma in situ (CIS), > or = pT2 disease, or intraoperative complications, patients were discontinued.

INTERVENTION

We used a single, postoperative 30-40-min instillation of GEM (2000 mg/100 ml of saline) or PBO (100 ml of saline) followed by continuous bladder irrigation for > or = 20 h. A second TUR (no instillation) and adjuvant bacillus Calmette-Guérin (BCG) instillations were allowed.

MEASUREMENTS

Primary outcome was recurrence-free survival (RFS). Secondary outcomes included type of recurrence and adverse events. To detect a difference in RFS, 191 recurrences were required (80% power, log-rank-test, alpha = 0.050).

RESULTS AND LIMITATIONS

Two hundred forty-eight patients (69.9%, GEM, PBO: 124, 124) had histologically confirmed pTa/pT1 G1-3 Gx tumour and were eligible for efficacy (GEM: 76.6% male; median age: 65 yr; PBO: 83.1% male; median age: 67 yr). Treatment groups were balanced (pTa: 75.0%, 71.0%; G1-G2: 85.5%, 87.9%; recurrent tumour: 24.2%, 21.0%; BCG: 10.5%, 16.9%). After a median follow-up of 24 mo, there were only 94 recurrences and 11 deaths. The study was terminated early based on predefined decision criteria. RFS was high in both groups (12-mo RFS [95% confidence interval (CI)]: GEM: 77.7% [68.8-84.3]; PBO: 75.3% [66.3-82.3]). There was no significant group difference (hazard ratio [HR]: 0.946 [0.64-1.39], log-rank test, p=0.777).

CONCLUSIONS

In this study of NMIBC, the immediate single instillation of GEM 2000 mg/100 ml of saline after TUR was not superior to PBO in terms of RFS. Rigid continuous irrigation and improved TUR/cystoscopy techniques may have contributed to the high RFS in both groups.

Human bladder cancer diagnosis using Multiphoton microscopy

At the time of diagnosis, approximately 75% of bladder cancers are non-muscle invasive. Appropriate diagnosis and surgical resection at this stage improves prognosis dramatically. However, these lesions, being small and/or flat, are often missed by conventional white-light cystoscopes. Furthermore, it is difficult to assess the surgical margin for negativity using conventional cystoscopes. Resultantly, the recurrence rates in patients with early bladder cancer are very high. This is currently addressed by repeat cystoscopies and biopsies, which can last throughout the life of a patient, increasing cost and patient morbidity. Multiphoton endoscopes offer a potential solution, allowing real time, non-invasive biopsies of the human bladder, as well as an up-close assessment of the resection margin. While miniaturization of the Multiphoton microscope into an endoscopic format is currently in progress, we present results here indicating that Multiphoton imaging (using a bench-top Multiphoton microscope) can indeed identify cancers in fresh, unfixed human bladder biopsies. Multiphoton images are acquired in two channels: (1) broadband autofluorescence from cells, and (2) second harmonic generation (SHG), mostly by tissue collagen. These images are then compared with gold standard hematoxylin/eosin (H&E) stained histopathology slides from the same specimen. Based on a "training set" and a very small "blinded set" of samples, we have found excellent correlation between the Multiphoton and histopathological diagnoses. A larger blinded analysis by two independent uropathologists is currently in progress. We expect that the conclusion of this phase will provide us with diagnostic accuracy estimates, as well as the degree of inter-observer heterogeneity.