Role of 5-aminolevulinic acid in the diagnosis and treatment of superficial bladder cancer: improvement in diagnostic sensitivity

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.

Photodynamic Diagnosis and Therapy in Non-Muscle-Invasive Bladder Cancer

Bladder cancer (BC) possesses distinct molecular profiles that influence progression depending on its biological nature and delivered treatment intensity. Muscle-invasive BC (MIBC) and non-MIBC (NMIBC) demonstrate great intrinsic heterogeneity regarding different prognoses, survival, progression, and treatment outcomes. Transurethral resection of bladder tumor (TURBT) is the standard of care in treating NMIBC and serves both diagnostic and therapeutic purposes despite the prevalent recurrence and progression among many patients. In particular, flat urothelial carcinoma in situ and urothelial carcinoma with lamina propria invasion are the major precursors of MIBC. A new-generation photosensitizer, 5-Aminolevulinic acid (5-ALA), demonstrates high tumor specificity by illuminating the tumor lesion with a specific wavelength of light to produce fluorescence and has been studied for photodynamic diagnosis to detect precise tumor areas by TURBT. Additionally, it has been applied for treatment by producing its cytotoxic reactive oxygen species, as well as screening for urological carcinomas by excreting porphyrin in the blood and urine. Moreover, 5-ALA may contribute to screening before and after TURBT in NMIBC. Here, we summarize the updated evidence and ongoing research on photodynamic technology for NMIBC, providing insight into the potential for improving patient outcomes.

Development of a Pocket Nomogram to Predict Cancer and Disease Specific Survival After Radical Cystectomy For Bladder Cancer: The CRAB Nomogram

OBJECTIVES

To develop an easy tool to predict cancer specific (CSS) and disease-free survival (DFS) in patients with bladder cancer treated with radical cystectomy.

METHODS

Data from a consecutive series of 2395 patients with primitive or progression to muscle invasive bladder cancer (MIBC) undergone to radical cystectomy and lymph nodes dissection in 5 centers were evaluated. Using Cox proportional hazards analyses, the Cancer of the bladder risk assessment (CRAB) nomogram was generated. Accuracy of the nomogram was evaluated by Harrell's C test. Internal validation of the model was performed using 200 bootstraps.

RESULTS

Median age was 66 (IQR 58/73) years; 612/2395 (26%) patients presented an advanced pathological stage (≥pT3a); 478/2395 (20%) presented positive lymph nodes. Overall, 729/2395 (30%) presented local or distant recurrence with a median DFS of 42 (IQR 14/89) months. Overall, 642/2395 (27%) died of bladder cancer with a median follow up of 48 (IQR 22/92) months. On univariate Cox proportional hazards analyses, age, stage, and lymph nodes density were a significant predictor of 3 and5 years CSS and DFS. Accuracy of the CRAB nomogram was 0.73 and 0.71 respectively.

CONCLUSION

CRAB nomogram can be a practical and easily applicable tool that may help urologists to classify the long-term CSS and DFS of patients treated with radical cystectomy and to predict the oncological outcome.

Comparison between 5-aminolevulinic acid photodynamic diagnosis and narrow-band imaging for bladder cancer detection

BACKGROUND

To compare 5-aminolevulinic acid (5-ALA)-mediated photodynamic diagnosis (PDD) with narrow-band imaging (NBI) for cancer detection during transurethral resection of bladder tumour (TURBT).

METHODS

Between June 2018 and October 2020, 114 patients and 282 lesions were included in the analysis. Patients were orally administered 5-ALA (20 mg/kg) 2 h before TURBT. The bladder was inspected with white light (WL), PDD, and NBI for each patient, and all areas positive by at least one method were resected or biopsied. The imaging data were then compared to the pathology results.

RESULTS

The sensitivities of WL, PDD, and NBI for detecting urothelial carcinoma were 88.1%, 89.6%, and 76.2%, respectively. The specificity, positive predictive value, and negative predictive value for detecting urothelial carcinoma were 47.5%, 80.9%, and 61.3%, respectively, for WL; 22.5%, 74.5%, and 46.2%, respectively, for PDD; and 46.3%, 78.2%, and 43.5%, respectively, for NBI. PDD was significantly more sensitive than NBI for all lesions (p < 0.001) and carcinoma in situ (CIS) lesions (94.6% vs. 54.1%, p < 0.001).

CONCLUSIONS

PDD can increase the detection rate of bladder cancer, compared to NBI, by greater than 10%. Therefore, 100% of CIS lesions can be detected by adding PDD to WL.

Validation of the COBRA nomogram for the prediction of cancer specific survival in patients treated with radical cystectomy for bladder cancer: An international wide cohort study

BACKGROUND

Recently, the Cancer of the Bladder Risk Assessment (COBRA) score has been introduced to estimate cancer specific survival (CSS) after radical cystectomy for bladder cancer.

OBJECTIVES

Aim of our study was to validate the COBRA score, assessing the effect of age, tumor stage and lymph-nodes status on CSS after cystectomy in patients with bladder cancer.

DESIGN, SETTING, AND PARTICIPANTS

A consecutive series of 2395 patients with primitive or recurrent bladder cancer treated with radical cystectomy in 4 centers were evaluated.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The role of COBRA score as predictor of CSS was assessed using the Kaplan Meier and Cox proportional hazards analyses. Accuracy of COBRA score was evaluated by Harrell's C test.

RESULTS AND LIMITATIONS

Median age was 66 (IQR 58/73) years. Overall, at a median follow-up of 48 (IQR 22/92) months, 642 patients (27%) died of bladder cancer. On Cox proportional hazards analyses, COBRA score was a significant predictor of CSS (HR 1.54, 95%CI 1.47-1.61) (Table 1). The predictive accuracy of the COBRA score was 0.71. A sub analysis including pooled COBRA score (0 vs 1-3 vs 4 vs 5-7) improved the clinical applicability with the same accuracy.

CONCLUSION

In our experience, the COBRA score is an excellent tool to predict cancer specific survival. The COBRA Score represents a practical and easy tool that may help urologists to classify the CSS of patients treated with radical cystectomy, to predict the oncological outcome and finally to counsel bladder cancer patients.

Diagnostic accuracy of photodynamic diagnosis with 5-aminolevulinic acid, hexaminolevulinate and narrow band imaging for non-muscle invasive bladder cancer

Objective: To assess the diagnostic test accuracy (DTA) of photodynamic diagnosis with 5-aminolaevulinic acid (5-ALA), hexylaminolevulinate (HAL) and narrow band imaging (NBI) for non-muscle-invasive bladder cancer (NMIBC), with white light-guided cystoscopy (WLC) as reference standard. Materials and Methods: A systematic review and narrative synthesis was performed in accordance with PRISMA. Major electronic databases were searched until 20th May 2019. All studies assessing the DTA of 5-ALA, HAL and NBI compared with WLC at patient and lesion-level were included. Relevant sensitivity analyses and risk of bias (RoB) assessment were undertaken. Results: 26 studies recruiting 3979 patients were eligible for inclusion. For patient-level analysis, NBI appeared to be the best (median sensitivity (SSY) 100%, median specificity (SPY) 68.45%, median positive predictive value (PPV) 90.75%, median negative predictive value (NPV) 100% and median false positive rate (FPR) 31.55%), showing better DTA outcomes than either HAL or 5-ALA. For lesion-level analysis, median SSY across NBI, HAL and 5-ALA were 93.08% (IQR 87.04-98.81%), 93.16% (IQR 91.48-97.04%) and 94.42% (IQR 82.37-95.73%) respectively. As for FPR, median values for NBI, HAL and 5-ALA were 20.40% (IQR 13.68-27.36%), 17.43% (IQR 12.79-22.40%) and 28.12% (IQR 22.08-42.39%), respectively. Sensitivity analyses based on studies with low to moderate RoB and studies with n>100 patients show similar findings. Conclusions: NBI appears to outperform 5-ALA and HAL in terms of diagnostic accuracy. All three modalities present high FPR, hence indicating the ability to detect additional cases and lesions beyond WLC.

Diagnostic performance of image technique based transurethral resection for non-muscle invasive bladder cancer: systematic review and diagnostic meta-analysis

OBJECTIVE

To explore the diagnostic performance of image technique based transurethral resection for bladder cancer, with white light-guided cystoscopy (WLC) as the reference standard.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed/MEDLINE, Web of Science, the Cochrane Library, Central Register of Controlled Trials and Embase from inception to 31 March 2018.

METHODS

Included studies reported the diagnostic performance of photodynamic diagnosis (PDD) with 5-aminolevulinic acid (5-ALA), PDD with hexaminolevulinic acid (HAL) or narrow band imaging (NBI), with WLC as the reference standard at the patient or lesion level. The studies' risk of bias (RoB) was assessed using Quality Assessment of Diagnostic Studies-2. Data were pooled using a random effect diagnostic meta-analysis, and subgroup analyses were performed.

RESULTS

Twenty-six studies comprising a total of 3979 patients were included in this diagnostic meta-analysis. Pooled sensitivity (SSY), specificity (SPY), diagnostic OR (DOR) and area under the receiver operating characteristic curve (AUROC) values were calculated per group for NBI, HAL and 5-ALA at the lesion or patient level. NBI showed significant diagnostic superiority compared with WLC at the lesion level (SSY 0.94, 95% CI 0.82 to 0.98; SPY 0.79, 95% CI 0.73 to 0.85; DOR 40.09, 95% CI 20.08 to 80.01; AUROC 0.88, 95% CI 0.85 to 0.91). NBI presented the highest DOR (358.71, 95% CI 44.50 to 2891.71) in the patient level. Subgroup analyses were performed on studies with low to moderate RoB and at least 100 patients at the lesion level. These results were consistent with those of the overall analysis.

CONCLUSIONS

Pooled data indicated that image technique based transurethral resection (NBI, HAL and 5-ALA) showed diagnostic superiority compared with WLC. Moreover, NBI is potentially the most promising diagnostic intervention, showing the best diagnostic performance outcomes. Further prognostic outcomes of novel imaging technologies compared with those WLC should be explored in addition to current diagnostic performance analysis.

Application of novel targeted molecular imaging probes in the early diagnosis of upper urinary tract epithelial carcinoma

Imaging techniques of upper tract urothelial carcinoma (UTUC) are presently limited. Upconversion particles (UCPs) could be used to target tumors for imaging. The present study aimed to assess the value of a nano-UCP as a diagnostic probe for deep tumor tissue, including UTUC. Polymer-coated water-soluble UCPs were synthesized. The pH Low Insertion Peptide (pHLIP) polypeptide was synthesized using the solid phase method. The silane shell surface was modified to present amino or carboxyl groups. Succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate was used for the coupling of the polypeptide to the UCPs. An animal model of subcutaneous tumor was established in 4-week old nude mice using UTUC cells. Urinary tract epithelial cancer T₂₄ cells were injected into the diaphragm below the heart. PHLIP-UCP solution (1 ml) was injected into the abdominal cavity of each animal. Optical detection was performed using a small animal living body multispectral imaging system. UCPs dispersed in chloroform emitted no light under natural light, while they emitted a green light when excited with a 980-nm laser. The maximum emission wavelength of Ho³⁺-doped UCPs was ~550 nm and the red emission region was ~650 nm. As the coated UCPs possessed a tendency to agglomerate and precipitate, the yield of the UCPs in the aqueous phase was reduced. Tumors could be successfully imaged in tumor-bearing mice. NaYF₄: Yb, Ho³⁺ UPCs could be used for the detection of UTUC, thus further studies are required to determine if it could be used in larger animals with deeper tumors.

Recommendations for the improvement of bladder cancer quality of care in Canada: A consensus document reviewed and endorsed by Bladder Cancer Canada (BCC), Canadian Urologic Oncology Group (CUOG), and Canadian Urological Association (CUA), December 2015

This initiative was undertaken in response to concerns regarding the variation in management and in outcomes of patients with bladder cancer throughout centres and geographical areas in Canada. Population-based data have also revealed that real-life survival is lower than expected based on data from clinical trials and/or academic centres. To address these perceived shortcomings and attempt to streamline and unify treatment approaches to bladder cancer in Canada, a multidisciplinary panel of expert clinicians was convened last fall for a two-day working group consensus meeting. The panelists included urologic oncologists, medical oncologists, radiation oncologists, patient representatives, a genitourinary pathologist, and an enterostomal therapy nurse. The following recommendations and summaries of supporting evidence represent the results of the presentations, debates, and discussions. Methodology

Is photodynamic diagnosis ready for introduction in urological clinical practice?

The aim of this review is to provide an up-to-date review of the available literature on photodynamic diagnosis (PDD) for nonmuscle-invasive bladder cancer, to present the technique in a comprehensive approach and, finally, to discuss the relevance of PDD in clinical practice in terms of indications, outcomes and its development trend. A literature search was conducted up to July 2012, using MEDLINE and EMBASE via Ovid databases to identify published studies on PDD for nonmuscle-invasive bladder cancer. Only English-language and human-based full manuscripts that reported on case series and studies with >40 participants, concerning clinical evidence of the technique, its efficacy and safety data were included. Evidence showed that PDD significantly improves detection of bladder cancer compared with standard white-light cystoscopy, having proven to be more effective for the diagnosis of carcinoma in situ. This condition seems to facilitate more complete resections, resulting in a lower residual tumor rate, which, in turn consecutively leads to higher recurrence-free survival rates. The literature search demonstrated that for mid- and long-term follow-up, PDD showed acceptable outcomes in terms of tumor detection, as well as lower residual tumor and lower recurrence rates compared with white-light cystoscopy. It has proven to be safe and well tolerated; the major limitations of PDD are its low specificity and elevated costs.

Hexyl aminolevulinate-guided fluorescence cystoscopy in the diagnosis and follow-up of patients with non-muscle-invasive bladder cancer: a critical review of the current literature

CONTEXT

Controversy exists regarding the therapeutic benefit and cost effectiveness of photodynamic diagnosis (PDD) with 5-aminolevulinic acid (5-ALA) or hexyl aminolevulinate (HAL) in addition to white-light cystoscopy (WLC) in the management of non-muscle-invasive bladder cancer (NMIBC).

OBJECTIVE

To systematically evaluate evidence regarding the therapeutic benefits and economic considerations of PDD in NMIBC detection and treatment.

EVIDENCE ACQUISITION

We performed a critical review of PubMed/Medline, Embase, and the Cochrane Library in October 2012 according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. Identified reports were reviewed according to the Consolidated Standards of Reporting Trials (CONSORT) and Standards for the Reporting of Diagnostic Accuracy Studies (STARD) criteria. Forty-four publications were selected for inclusion in this analysis.

EVIDENCE SYNTHESIS

Included reports used 5-ALA (in 26 studies), HAL (15 studies), or both (three studies) as photosensitising agents. PDD increased the detection of both papillary tumours (by 7-29%) and flat carcinoma in situ (CIS; by 25-30%) and reduced the rate of residual tumours after transurethral resection of bladder tumour (TURBT; by an average of 20%) compared to WLC alone. Superior recurrence-free survival (RFS) rates and prolonged RFS intervals were reported for PDD, compared to WLC in most studies. PDD did not appear to reduce disease progression. Our findings are limited by tumour heterogeneity and a lack of NMIBC risk stratification in many reports or adjustment for intravesical therapy use in most studies. Although cost effectiveness has been demonstrated for 5-ALA, it has not been studied for HAL.

CONCLUSIONS

Moderately strong evidence exists that PDD improves tumour detection and reduces residual disease after TURBT compared with WLC. This has been shown to improve RFS but not progression to more advanced disease. Further work to evaluate cost effectiveness of PDD is required.

New imaging techniques for non-muscle invasive bladder cancer: ready for primetime

Treatment of non-muscle invasive bladder cancer (NMBIC) requires direct visual appreciation of the tumor. Transurethral resection that is dependent solely on white light cystoscopy (WLC) often fails to accurately stage or completely resect NMIBC. These deficiencies of WLC are significant contributors to the high rates of recurrence and eventual progression to muscle invasive disease. This article looks at technologies that are being used in adjunct to WLC to augment the urologist's ability to identify, stage, and treat NMIBC.

Recent advances in microbial production of δ-aminolevulinic acid and vitamin B12

δ-aminolevulinate (ALA) is an important intermediate involved in tetrapyrrole synthesis (precursor for vitamin B12, chlorophyll and heme) in vivo. It has been widely applied in agriculture and medicine. On account of many disadvantages of its chemical synthesis, microbial production of ALA has been received much attention as an alternative because of less expensive raw materials, low pollution, and high productivity. Vitamin B12, one of ALA derivatives, which plays a vital role in prevention of anaemia has also attracted intensive works. In this review, recent advances on the production of ALA and vitamin B12 with novel approaches such as whole-cell enzyme-transformation and metabolic engineering are described. Furthermore, the direction for future research and perspective are also summarized.

Photodynamic diagnosis in non-muscle-invasive bladder cancer: a systematic review and cumulative analysis of prospective studies

CONTEXT

The clinical benefit of photodynamic diagnosis (PDD) with 5-aminolevulinic acid or hexaminolevulinate in addition to white-light cystoscopy (WLC) in bladder cancer has been discussed controversially.

OBJECTIVE

To assess in a systematic review the effect of PDD in addition to WLC on (1) the diagnosis and (2) the therapeutic outcome of primary or recurrent non-muscle-invasive bladder cancer investigated by cystoscopy or transurethral resection.

EVIDENCE ACQUISITION

An electronic database search of Medline, Embase, the Cochrane Library, and CancerLit was undertaken, plus hand searching of relevant congress abstracts and urologic journals. Trials were included if they prospectively compared WLC with PDD in bladder cancer. The review process followed the guidelines of the Cochrane Collaboration. Two reviewers evaluated independently both trial eligibility and methodological quality and data extraction.

EVIDENCE SYNTHESIS

The primary end point of diagnostic accuracy was additional detection rate. The primary end points of therapeutic outcome were residual tumour at second resection and recurrence-free survival (RFS). Seventeen trials were identified. Twelve diagnostic trials used WLC and PDD with the same patients. Seven reported results for the subgroup of patients with carcinoma in situ (CIS). Five randomised trials studied therapeutic outcome. The results were combined in random effects meta-analyses if end points, designs, and populations were comparable. Twenty percent (95% confidence interval [CI], 8-35) more tumour-positive patients were detected with PDD in all patients with non-muscle-invasive tumours and 39% (CI, 23-57) more when only CIS was analysed. Heterogeneity was present among diagnostic studies even when the subgroup of patients with CIS was investigated. Residual tumour was significantly less often found after PDD (odds ratio: 0.28; 95% CI, 0.15-0.52; p<0.0001). RFS was higher at 12 and 24 mo in the PDD groups than in the WLC-only groups. The combined p value of log-rank tests of RFS was statistically significant (0.00002).

CONCLUSIONS

PDD detects more bladder tumour-positive patients, especially more with CIS, than WLC. More patients have a complete resection and a longer RFS when diagnosed with PDD.

Raman spectroscopy of bladder tissue in the presence of 5-aminolevulinic acid

Raman spectroscopy has the ability to provide differential diagnosis of different cancers with high sensitivity and specificity. A major limitation in its clinical application is the weak nature of Raman signal, which inhibits scanning large surface areas of tissues. In bladder cancer diagnosis, fluorescence-guided endoscopy with 5-aminolevulinic acid (5-ALA) has gained interest as a technique that can provide such spatial differentiation, thus improving early detection and more complete removal of superficial tumors. However, several studies have demonstrated the poor specificity of this modality. Combining fluorescence with Raman spectroscopy could improve its diagnostic capability. However, little is known about the effect of agents such as 5-ALA on Raman spectra of tissue. In this paper, we present measuring Raman spectroscopy from benign and malignant bladder tissues in the presence of 5-ALA and attempt to evaluate the potential to discriminate between different pathologies. Raman spectra were recorded from 92 bladder biopsies without 5-ALA and 38 biopsies with 5-ALA using a Raman microspectrometer system at 830nm excitation. Empirical and multivariate statistical techniques were used for data analysis. Algorithms were developed to determine the effect of 5-ALA on tissue and its influence on the prediction ability of a preliminary benign/malignant prediction model. In samples with 5-ALA, an overall decrease in Raman intensity was observed when compared to the Raman spectra from samples without 5-ALA. Additionally, differences in relative intensities at 1270 and 1330cm(-1) were also noted. However, significant differences were observed in the Raman spectra of benign and malignant samples with 5-ALA indicating the potential of using Raman spectroscopy for discriminating bladder cancer in the presence of 5-ALA. The Principal-Component fed Linear-Discriminant Analysis (PCA/LDA) algorithm derived from biopsies in the absence of 5-ALA used to predict biopsies in the presence of 5-ALA resulted in an overall sensitivity and specificity of 42.6% and 71.1%, respectively. This suggests the presence of 5-ALA in tissue affects the Raman spectra. A PCA/LDA algorithm based on fluorescence information (i.e. PpIX fluorescence positive or negative) and the Raman spectrum of 5-ALA biopsies, had a sensitivity and specificity of 100% and 80.8%, respectively. This study demonstrates that applying 5-ALA affects the Raman spectra of bladder tissues. However, benign/malignant differentiation can be accomplished with a preliminary PCA/LDA algorithm, suggesting the potential of a combined diagnostic modality in vivo.

Photodynamic diagnosis for superficial bladder cancer: do all risk-groups profit equally from oncological and economic long-term results?

OBJECTIVE

Photodynamic diagnosis (PDD) of superficial bladder cancer decreases recurrence rates. We present oncological results of a randomized, prospective study, comparing transurethral resection (TUR) performed under conventional white light (WL) with PDD. The follow-up period is the longest reported to date. As costs might be reimbursed by prolonged recurrence-free survival in certain patients cost analysis in regard to risk-groups was performed.

MATERIAL AND METHODS

Using chi-square test and log-rank test we compared recurrence rates of 103 patients after WL-TUR and of 88 patients after PDD-TUR. Cost analysis was performed according to risk-groups of recurrence.

RESULTS

Mean follow-up was 99 months. Recurrence rate was 57% in WL vs. 28% in PDD (p < 0.001). Costs incurred by subsequent TUR averaged euro 2310 per WL patient vs. euro 713 per PDD patient. Savings per patient by PDD amounted to euro 1597. PDD costs were reimbursed in low, intermediate and high risk patients, respectively.

CONCLUSIONS

PDD-TUR is significantly superior to conventional WL-TUR in terms of recurrence rate. While economic benefit is most prominent in intermediate risk patients, PDD related costs are reimbursed in all risk-groups.

Expression of a hemA gene from Agrobacterium radiobacter in a rare codon optimizing Escherichia coli for improving 5-aminolevulinate production

The 5-aminolevulinate (ALA) synthase gene (hemA) from Agrobacterium radiobacter zju-0121, which was cloned previously in our laboratory, contains several rare codons. To enhance the expression of this gene, Escherichia coli Rosetta(DE3), which is a rare codon optimizer strain, was picked out as the host to construct an efficient recombinant strain. Cell extracts of the recombinant E. coli were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under the appropriate conditions. The results indicated that the activity of ALA synthase expressed in Rosetta(DE3)/pET-28a(+)-hemA was about 20% higher than that in E. coli BL21(DE3). Then the effects of precursors (glycine and succinate) and glucose, which is an inhibitor for ALA dehydratase as well as the carbon sources for cell growth, on the production of 5-aminolevulinate were investigated. Based on an optimal fed-batch culture system described in our previous work, up to 6.5 g/l (50 mM) ALA was produced in a 15-l fermenter.

Clinically Relevant Reduction in Risk of Recurrence of Superficial Bladder Cancer Using 5-Aminolevulinic Acid-Induced Fluorescence Diagnosis: 8-Year Results of Prospective Randomized Study

OBJECTIVES

Several studies have shown that 5-aminolevulinic acid (5-ALA)-induced fluorescence cystoscopy improves the detection of superficial bladder cancer. The results have suggested a reduced rate of recurrent tumors with the use of 5-ALA fluorescence before bladder tumor resection. We performed a prospective, randomized trial to investigate whether the long-term tumor recurrence and residual tumor rates can be decreased using 5-ALA fluorescence diagnosis (FD).

METHODS

A total of 301 patients with suspected superficial bladder carcinoma were randomized to transurethral resection (TUR) using conventional white light (WL) or FD. TUR was repeated to evaluate the residual tumor rate. In addition, patients were followed up for a median of 83 (WL) and 86 (FD) months to evaluate recurrence-free survival (RFS).

RESULTS

Of the 301 patients, 191 were available for the efficacy analysis. The residual tumor rate was 25.2% in the WL arm versus 4.5% in the FD arm (P <0.0001). The RFS rate after 2, 4, 6, and 8 years was 73%, 64%, 54%, and 45% in the WL group and 88%, 84%, 79%, and 71% in the FD group, respectively, revealing a statistically significant difference in favor of fluorescent TUR (P = 0.0003).

CONCLUSIONS

5-ALA-induced FD is significantly superior statistically to conventional WL TUR with respect to the residual tumor rate and RFS. This advantage of decreased bladder tumor recurrence risk was maintained with high statistical significance for at least 8 years. The differences in RFS imply that FD offers a clinically relevant procedure to reduce the incidence of tumor recurrence.

5-Aminolevulinate production with recombinant Escherichia coli using a rare codon optimizer host strain

The 5-aminolevulinate (ALA) synthase gene (hemA) containing several codons rarely used by Escherichia coli was cloned from the genome of Rhodobacter sphaeroides and optimized in two strains of Escherichia coli: BL21(DE3) and Rosetta(DE3), which is a rare codon optimizer strain. The effects of initial isopropyl-beta-D: -thiogalactopyranoside (IPTG) concentration, induction time, and temperature on enzyme activity were studied and compared for two strains. The results indicated that the ALA synthase expressed by Rosetta(DE3)/pET-28a(+)-hemA was higher than that by BL21(DE3)/pET-28a(+)-hemA. The initial precursors, glycine and succinate, and initial glucose, which is an inhibitor for both ALA synthase and dehydratase, were observed to be the key factors affecting ALA production. ALA synthase activity was generally higher with Rosetta(DE3) than with BL21(DE3), so was ALA biosynthesis. Based on the optimal culture system using Rosetta(DE3), the yield of ALA achieved 3.8 g/l (29 mM) under the appropriate conditions in fermenter.

Seven Years’ Experience with 5-Aminolevulinic Acid in Detection of Transitional Cell Carcinoma of the Bladder

OBJECTIVES

Photodynamic diagnosis (PDD) using 5-aminolevulinic acid has proved to be a procedure with an outstanding sensitivity for the detection of transitional cell carcinoma of the bladder, in particular in the detection of flat urothelial lesions. We report on our clinical results with 875 patients (1713 PDD procedures) between March 1995 and March 2002.

METHODS

A total of 1713 PDD procedures were done in 875 patients. Fluorescence imaging was performed 2 to 3 hours after instillation of 50 mL of a 3% solution of 5-aminolevulinic acid into the bladder by an incoherent light source. In total, specimens from 4630 lesions (2.7 lesions/PDD) were taken.

RESULTS

In 34.8% of all biopsies, the histologic finding was malignant; 23.7% of these biopsies had been taken only because of positive fluorescence. In 28.5% of the positive biopsies, flat lesions had been identified. Also, 43.4% of carcinoma in situ and 30.7% of dysplasia II degrees were detected only by positive fluorescence. Of all tumor lesions, 92.0% were detected by PDD compared with 76.3% detected by white light endoscopy.

CONCLUSIONS

PDD has proved to be an effective detection device for superficial bladder cancer.

Bladder cancer: Epidemiology, staging and grading, and diagnosis

Bladder cancer is a heterogeneous disease with a variable natural history. At one end of the spectrum, low-grade Ta tumors have a low progression rate and require initial endoscopic treatment and surveillance but rarely present a threat to the patient. At the other extreme, high-grade tumors have a high malignant potential associated with significant progression and cancer death rates. In the Western world, bladder cancer is the fourth most common malignancy in men and the eighth most common in women. In Europe and the United States, bladder cancer accounts for 5% to 10% of all malignancies in men. The risk of developing bladder cancer at <75 years of age is 2% to 4% for men and 0.5% to 1% in women compared with the risk of lung cancer, for example, which is 8% in men and 2% in women. For the geographic and temporal comparison of bladder cancer incidence, it is crucial to separate the low-grade from the high-grade tumors. In epidemiologic studies on risk factors for bladder cancer, it is important to distinguish the low-grade Ta tumors from high-grade carcinoma in situ (CIS) and tumors >T1. Current studies do not support the routine screening for bladder cancer. However, prospective long-term studies are required to evaluate the benefits of bladder cancer screening, particularly in those at high risk. After assessing all available evidence, the Epidemiology and Diagnosis Committee has made recommendations on various diagnostic issues, including pathologic evaluation, urinary cytology, and imaging studies. Optimal resection techniques, role of repeat transurethral resection in high-grade T1 tumors, random bladder biopsy, and prostatic urethral biopsy are discussed, and appropriate recommendations are made according to the strength of available evidence.

Reduced specificity of 5-ALA induced fluorescence in photodynamic diagnosis of transitional cell carcinoma after previous intravesical therapy

OBJECTIVE

Photodynamic diagnosis (PDD) for the detection of bladder cancer has become a diagnostic tool in several hospitals. Several studies have reported different rates of false positive biopsies using 5-aminolevulinic acid induced fluorescence. In this study we evaluated the effect of previous intravesical therapy on the false positive biopsy rate.

METHODS

Two hours prior to endoscopy 1.5g ALA dissolved in 50ml 1.4% NaHCO(3) solution was instilled intravesically. For fluorescence excitation a blue light source (D-light, Karl Storz) was used. Under white and fluorescence light guidance, tumor locations were recorded, cold cup biopsies were taken and tumors were resected. Patients were divided into 3 groups, last intravesical therapy (IVT) less than 6 months prior to PDD, last IVT longer than 6 months before PDD and no previous IVT.

RESULTS

In total 917 biopsies were taken in 249 procedures of fluorescent and non-fluorescent areas. White light endoscopy revealed 270 and PDD 378 of in total 390 tumors, resulting in a sensitivity of 97% and specificity of 49% for PDD. Pathologic evaluation considered 270 fluorescent biopsies as false positive. The rate of false positive biopsies was 25.7% in the group No IVT, 30.6% in the group PDD-IVT >6 months, whereas in the group "within 6 months after intravesical therapy" the rate was 39.6% (p<0.025). When premalignant lesions such as dysplasia II are considered tumor the difference between the groups is even more significant (p<0.001).

CONCLUSIONS

The procedure has a high sensitivity for superficial bladder cancer and decreases the number of overlooked lesions. Recent intravesical therapy results in significantly more false positive fluorescent biopsies. Since patient outcome might predominantly be determined by the early detection and subsequent treatment of (pre)malignant tissue we suggest that PDD is justified even shortly after intravesical therapy.

Do patients profit from 5-aminolevulinic acid-induced fluorescence diagnosis in transurethral resection of bladder carcinoma?

OBJECTIVES

To evaluate in a prospective study the influence of fluorescence diagnosis (FD) controlled transurethral resection of bladder tumors on therapeutic consequences. The aim was to determine in how many patients FD led to a change in treatment strategy compared with conventional white light (WL) cystoscopy.

METHODS

A total of 279 patients with suspected bladder tumors underwent transurethral resection using FD in addition to WL cystoscopy. The number of additional tumor-positive patients, staging change, number of multilocular tumors exclusively detected by FD, and resulting therapeutic consequences compared with the results after WL cystoscopy were investigated. In addition a biopsy-based evaluation was performed.

RESULTS

Tumor or dysplasia II degrees (moderate dysplasia) was detected in 177 patients. In 168 patients, tumor was detected by WL cystoscopy, and in 9 (5.1%) of the patients, tumor was completely overlooked by WL cystoscopy and diagnosed exclusively by FD (n = 3 TaG1-G2, n = 2 carcinoma in situ, n = 1 greater than T1, and n = 3 dysplasia II degrees ). Multilocular tumor involvement was detected in 10 cases using FD, and a change in the stage by detection of coexisting dysplasia II degrees and carcinoma in situ occurred in 8 patients. In 27 patients (15.3%), additional information was obtained by exclusive detection of tumors by FD. This resulted in a change in the treatment strategy for 16 patients (9%).

CONCLUSIONS

FD leads to an improvement in the diagnosis of bladder carcinoma. It allows the early selection of the best treatment option and thus has a potentially positive effect on the prognosis of the affected patients.

Fluorescence detection of bladder cancer: a review

An effective therapeutic outcome in the treatment of bladder cancer is largely defined by its early detection. In this context, big expectations have been placed on the fluorescence-guided diagnosis of bladder cancer. This paper reviews the applications of endo- and exogenous fluorescence for early diagnosis of in situ carcinoma of the bladder. Despite certain advantages of autofluorescence, exogenous fluorescence, based on the intravesical instillation of fluorophores with the following visible light excitation, has been shown to be more effective in terms of sensitivity and specificity for detecting carcinoma in situ. The equipment consists of a slightly modified light source in order to choose between white (conventional endoscopy) or blue light (fluorescence endoscopy) excitation, and specific lenses, in order to enhance maximally the contrast between normal (blue) autofluorescence and red fluorescence from malignancies. Among exogenous fluorophores, a particular emphasis will be put on the 5-aminolevulinic acid (ALA), its ester derivative (h-ALA) and hypericin. These dyes demonstrated an excellent sensitivity above 90% and specificity ranging from 70% to 90%.