Is photodynamic diagnosis ready for introduction in urological clinical practice?

Time to Turn on the Blue Lights: A Systematic Review and Meta-analysis of Photodynamic Diagnosis for Bladder Cancer

Context

White light (WL) cystoscopy and transurethral resection of bladder tumour (TURBT) comprise the current gold standard technique for detecting and grading bladder cancer. However, with WL cystoscopy, recurrence following initial TURBT is high, and identification of smaller tumours and carcinoma in situ is poor. Photodynamic diagnosis (PDD) has been developed to improve the detection of bladder.

Objective

To assess the effect of PDD-guided TURBT compared with WL on recurrence rates (RRs) in non-muscle-invasive bladder cancer (NMIBC).

Evidence acquisition

A systematic review of the literature from inception to April 2020 using Medline, EMBASE, and CENTRAL was undertaken. Randomised control trials comparing TURBT undertaken with PDD to WL that reported RRs of at least 12 mo were included in the analysis. The primary outcomes were RRs at 12 and 24 mo. The secondary outcomes were reported adverse effects. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assess the certainty of the evidence.

Evidence synthesis

Twelve randomised controlled trials (2288 patients) were included for the meta-analysis. PDD was found to reduce RRs at 12 mo (RR 0.73, confidence interval [CI] 0.60-0.88) and 24 mo (RR 0.75, CI 0.62-0.91). There was an increased risk of recurrence for patients undergoing WL at 12 mo (hazard ratio [HR] 1.14, CI 1.05-1.23) and 24 mo (HR 1.25, CI 1.15-1.35). Two studies reported recurrence data at 60 mo showing statistically significant outcomes in favour of PDD: one showed lower RRs for PDD (49% PDD vs 68% WL), whilst the other showed increased recurrence-free survival (68.2% PDD vs 57.3% WL). Adverse effects appeared to be minimal, though poorly reported. A GRADE analysis showed the evidence to be of moderate certainty overall.

Conclusions

This systematic review found that PDD reduced RRs and improved recurrence-free survival compared with WL in NMIBC over at least 2-yr follow-up. These effects may persist up to 5 yr. Further research in a pragmatic study looking at longer-term outcomes beyond 24 mo will help guide recommendations on clinical adoption.

Patient summary

This review suggests that photodynamic diagnosis, compared with white light cystoscopy, improves recurrence-free survival in non-muscle-invasive bladder cancer over at least 2 yr of follow-up. However, confirmatory pragmatic studies with longer-term outcomes are required for its clinical adoption.

Evans blue-mediated white-light detection of non-muscle-invasive bladder cancer: A preclinical feasibility and safety study using a rat bladder urothelial cell carcinoma model

Photodynamic diagnosis (PDD) improves the detection of non-muscle-invasive bladder cancer (NMIBC). However, white-light (WL) cystoscopy remains the technique routinely used in urological clinics. A more cost-effective but equally performant alternative to PDD may encompass the use of an intense tumoritropic dye in combination with WL cystoscopy. Using a preclinical setting, we investigated the practical aspects of the use of Evans blue (EB) dye for the possible future detection of NMIBC using WL cystoscopy. A solution of 1 and 5 mM EB was instilled into healthy and AY-27 tumor-bearing rat bladders. The bladders were then rapidly dissected and the inner walls were inspected for EB using WL stereomicroscopy. EB present in the bladders and the plasma was also quantified using high performance liquid chromatography. To assess the effects of repeated instillations on normal rat bladders, EB was instilled for 7 consecutive days, after which time the bladder wall was investigated histologically. To gain insight into the mechanisms underlying the selective accumulation of EB in malignant urothelium, RNA sequencing of urothelial tissue and subsequent comparative analysis were performed, with a specific focus on cell adhesion. The concentrations of EB were substantially higher in malignant bladders compared with those in healthy bladders, matching the blue staining of the inner bladder wall observed by stereomicroscopy. EB was equally present in the plasma of healthy and tumor-bearing subjects, although at low concentrations. Importantly, EB did not cause any abnormalities in the urothelium after 7 days of repeated instillation in normal rats. RNA sequencing of the urothelium indicated an abnormal expression of several genes related to cell adhesion in malignant urothelium compared with the normal urothelium. Our findings may be important for future clinical developments in the field of diagnostics for bladder cancer. Implementing the more cost-effective protocol of EB instillations in combination with WL cystoscopy may offer a benefit to patients as well as the healthcare system.

Results of a prospective randomized study assessing the efficacy of fluorescent cystoscopy-assisted transurethral resection and single instillation of doxorubicin in patients with non-muscle-invasive bladder cancer

OBJECTIVES

To assess the efficacy of two treatment options for non-muscle-invasive bladder cancer (NMIBC): (1) transurethral resection (TUR) guided by fluorescence cystoscopy (FC) with the use of 5-aminolevulinic acid (5-ALA) and (2) single early instillation of doxorubicin in a single-center open-label prospective randomized study with a 2 × 2 factorial design.

PATIENTS AND METHODS

Patients with clinical suspicion of primary or recurrent NMIBC were randomized into four study arms: FC-assisted TUR with 5-ALA and single instillation of doxorubicin, FC-assisted TUR without instillation, TUR in white light (WL) with single instillation of doxorubicin, and WL-TUR only. The study was designed to assess recurrence-free survival in arms with and without any of two interventions.

RESULTS

Of 525 patients included, 377 (72 %) were eligible for primary outcome assessment. The median follow-up was 54.8 months. FC statistically significantly decreased the risk of disease recurrence and progression with hazard ratio (HR) 0.56 (95 % CI 0.39-0.80, p = 0.001) and 0.33 (95 % CI 0.12-0.91, p = 0.031), respectively. The HRs for recurrence and progression for single instillation of doxorubicin were 0.76 (95 % CI 0.54-1.07, p = 0.11) and 0.65 (95 % CI 0.28-1.52, p = 0.32), respectively. The overall and cancer-specific survival rates did not differ significantly based on the therapeutic interventions.

CONCLUSIONS

In patients with NMIBC, FC-assisted TUR with 5-ALA results in a substantial recurrence and progression risk reduction as compared to WL-TUR. The single early postoperative instillation of doxorubicin did not have a statistically significant impact on recurrence and progression risks.

Biodistribution of Evans blue in an orthotopic AY-27 rat bladder urothelial cell carcinoma model: implication for the improved diagnosis of non-muscle-invasive bladder cancer (NMIBC) using dye-guided white-light cystoscopy

OBJECTIVES

To investigate the possibility of using Evans blue (EB) as a novel diagnostic tool to detect bladder tumours with white-light (WL) cystoscopy, in this preclinical study we examine the biodistribution of EB in the different layers (urothelium, submucosa, muscle) of a normal rat bladder and a rat bladder bearing a malignant urothelium composed of syngeneic AY-27 tumour cells.

MATERIALS AND METHODS

EB was instilled into both normal as well as tumour-bearing rat bladders. After instillation, bladders were removed and snap frozen in liquid nitrogen. The distribution of EB in the different layers was quantified using fluorescence microscopy. To gain more insight into the mechanism underlying the selective accumulation of EB in tumour tissue, bladder sections were prepared for ultrastructural investigations by means of transmission electron microscopy (TEM). In addition, we also examined the expression of E-cadherin, claudin-1 and desmoglein-1 by immunohistochemistry to study the integrity of the bladder wall, as these molecules are key constituents of adherens junctions, tight junctions and desmosomes, respectively.

RESULTS

In most cases, the accumulation of EB in malignant bladders was substantially higher than in healthy bladders, at least when 1 mm EB instillations were used. In case of a 1 mm EB instillation for 2 h, the EB-associated fluorescence in malignant urothelial tissue was 55-times higher than the fluorescence found in normal urothelium. Ultrastructurally, malignant tissue displayed wider intercellular spaces and a decreased number of cell junction components compared with normal tissue, pointing to defects in the urothelial barrier. There were no differences in the expression of E-cadherin, whereas desmoglein-1 staining was stronger in the membranes of healthy bladder urothelium compared with tumour tissue. Claudin-1 expression was negative in all samples tested.

CONCLUSION

EB is selectively taken up by tumour tissue after intravesical instillations in rats bearing bladder tumours. The lower expression of desmoglein-1 in tumour samples, together with the reduced presence of desmosomes seen with TEM, likely imply that desmosomes play an important role in the ultrastructural differences between healthy rat urothelium and tumour tissue, and secondary to that, to the differential uptake of EB in both tissues. We consider that our findings could be useful for future clinical developments in the field of diagnostics for bladder cancer.