5-aminolevulinic acid-induced fluorescence cystoscopy for photodynamic diagnosis of bladder tumors: Oral versus intravesical administration

Abstract

Objective:

This retrospective study aimed at comparing orally administered 5-aminolevulinic acid (5-ALA) to the intravesical (IV) route for the in vivo photodynamic diagnosis (PDD), follow-up, and guided transurethral resection of bladder tumors.

Materials and Methods:

A comparative retrospective review was conducted on adult patients who underwent 5-ALA-assisted cystoscopy for bladder tumor detection. Participants were divided into Group A, who received oral (ALA onco) powder, while Group B received 5-ALA intravesically. A comprehensive assessment, including patient history, physical examination, cytological urine analysis, ultrasound, and computed tomography scans, was performed. The sensitivity and specificity of white light cystoscopy were compared to PDD cystoscopy using both 5-ALA administration routes. Furthermore, the diagnostic accuracy of the oral versus the intarvesical route was directly compared. The associated toxicities were also identified. Patients were further categorized based on the morphological presence of muscle invasion. A further subgroup statistical analysis for the nonmuscle invasive category was carried out. Chi-square test was used to calculate (P) value for statistical significance, while Cohen’s d was used to assess the effect size. The confidence interval (CI) was denoted as 95%.

Results:

A total of 88 participants were included. Group A comprised 10 patients (8 males, aged 40–70 years), while Group B included 78 patients (58 males, aged 29–75 years). Oral 5-ALA demonstrated a sensitivity of 96%, compared to 60% for white light with a statistically significant difference (P = 0.025) with (95% CI 0.201–0.519). In terms of specificity, oral 5-ALA was statistically superior at 94%, compared to 80% with P = 0.024 (95% CI 0.160–0.519). On the other hand, IV 5-ALA showed 85.12% sensitivity compared to 70% for white light, which is statistically significant (P = 0.021) and (95% CI 0.231–0.279). There was no difference between white light and IV 5 ALA with regard to specificity (50% for both). On direct comparison, there was a statistically significant difference in favor of the oral form in terms of specificity (P = 0.008) with (95% CI 0.256, 0.624), whereas the oral 5-ALA showed higher sensitivity with no statistical difference. PDD significantly outperformed white light in detecting nonmuscle-invasive tumors as it picked up 24% additional lesions. During 15–24 months of follow-up, no recurrence was observed in Group A, while 29 patients (approximately one-third) in Group B experienced recurrence. No significant adverse effects were reported. Patients with bilharzia-associated bladder carcinoma did not behave differently.

Conclusion:

PDD using oral 5-ALA demonstrated superior diagnostic accuracy compared to IV administration and white light cystoscopy along with lower recurrence rate, making it the preferable option while larger scale and more powered studies are awaited.

INTRODUCTION

Bladder carcinoma is among the most prevalent urogenital tumors, with the majority being urothelial in origin.[1,2,3] Cystoscopy and biopsy remain the gold-standard diagnostic tools.[4] Over the years, there was a significant enhancements in cystoscopic techniques such as the development of rod lenses system, the Xenon light sources, the use of TV monitors, and contact microscopes.[5,6] More recently, novel technologies have emerged, including photodynamic diagnosis (PDD), narrow-band imaging, and confocal laser endomicroscopy.[7,8,9,10]

The major advantage of these new technologies including PDD is to enhance the detection of the premalignant and early-stage malignant lesions in the lower urinary tract.[11,12]

In particular, the positive impact of PDD using 5-aminolevulinic acid (5-ALA) on tumor recurrence and survival was also reported in well-powered systematic reviews and meta-analyses.[13,14,15]

Initially, intravesical (IV) 5-ALA was the primary pro-drug used for PDD in urology. More recently, a small-molecule form of 5-ALA has been synthesized through bacterial fermentation, leading to the development of an oral formulation by SBI Pharma Japan.[16,17]

5-ALA administration results in the transient formation of endogenous photoactive protoporphyrin IX (PPIX), which is normally converted into heme via Ferrochelatase enzyme activity. Due to the reduced metabolic activity of Ferrochelatase in cancer cells, PPIX accumulates.[18,19] In addition, increased activity of porphobilinogen deaminase and other enzymes involved in PPIX synthesis enhances fluorescence in tumors. Under blue light illumination, PPIX fluoresces red, making bladder tumors visible as red patches against a blue background of the normal mucosa.[20,21]

The data is scarce on direct comparison between the oral and IV routes given the associated significant cost of the oral form. Our study is the first from the region to report on the oral use of 5-ALA to our knowledge. Moreover, another novel aspect to our study is that it contained participants with bilharzia associated bladder carcinoma. This study was designed to assess if there is any superiority of either forms of PDD over each either in terms of diagnostic accuracy for bladder carcinoma in general as well as among the nonmuscle invasive category. It did also assess the associated toxicity from either forms.

MATERIALS AND METHODS

Study design and participants

A retrospective review was conducted on patients undergoing cystoscopic PDD for suspected bladder malignancy. Participants were divided into two groups based on the route of 5-ALA administration:

• Group A: Oral administration of 5-ALA (20 mg/kg, mixed with distilled water, taken 3–4 h before cystoscopy

• Group B: IV administration via Foley’s catheter using a freshly prepared 5-ALA solution instilled 1.5–4 h before cystoscopy.

On the morning of the cystoscopic examination, a Foley’s catheter (14–16 Ch) was inserted into the bladder under local anesthesia (2% Xylocain® gel) using appropriate antiseptic technique. The bladder was completely evacuated of the residual urine and the balloon was inflated with 10 ml of distilled water. One and a half grams of sterile 5-aminolevulenic acid is dissolved in 50 ml of a sterile 1.4% sodium bicarbonate solution. Given that 5-aminolevulenic acid solution can lose its activity by long storage (approximately 5 h); therefore immediate instillation into the bladder is of great consequence to achieve best possible effect. The prepared clear solution has a PH of approximately 4.9 at a concentration of 3% at the time of instillation. The solution is then instilled into the bladder using 50 cc sterile syringes and the catheter is clamped until the time of cystoscopic inspection. The clamping duration ranges between 1.5 and 4 h (2 h on average).

Cystoscopic procedure

For group (a) patients who received the oral ALA onco, the equipment used was ALA duck light source developed by SBI Pharma Japan utilizing LED technology to deliver light (white and blue). The equipment is supplied with pedal switch for excitation of blue light and white light. The procedure is monitored by TV screen and recorded using the attached recording system.

The bladder was first examined using white light, and any presence of a suspicious lesion was documented. The blue violet light is then activated, and with the use of the yellow filter lenses the bladder is examined again systematically. The presence of any suspicious lesion is marked again as red purple fluorescent patch in a blue background.

Complete transurethral resection was undertaken for all suspected areas. All the resected tissues were marked in respect to site and appearance. The resection was accomplished by deep resection with continuous blue/white light screening to achieve complete deep resection of the lesion. The irrigation fluid used for all the procedures is sterile glycine 1.5%. All biopsies taken were sent for histopathological examination.

For Group B, the bladder was evacuated after 2–3 h and the catheter was removed. Richard Wolf® cystoscopy system was used equipped with Xenon® light which delivers both white light and blue violet light which is necessary for the excitation of 5-ALA. The light source used in our study was a Xenon arc lamp with a corresponding band pass filter system. Blue violet light in the wave length range between (375 and 440 nm) was transmitted at maximal power of 260 mW through a bundle of glass fibers with a diameter of 1.8 mm. For endoscopic observation a special filter was incorporated into the lens of the scope. This helps to diminish the position of blue excitation light and provides an increased contrast between red fluorescing urothelial lesion and the nonfluorescing bladder wall that reflects the excitation light. The final diagnosis was obtained from the histopathological examination report.

Data analysis

Diagnostic accuracy was assessed by calculating the sensitivity and specificity of individual 5-ALA groups as well as calculating the sensitivity and specificity of the conventional white light. All groups were compared to each other. A further subgroup analysis was conducted among the nonmuscle invasive category including carcinoma in situ (CIS). We took in consideration the tumor grade, size, and multiplicity as confounders in our analysis. Sensitivity and specificity for tumor detection were calculated as per the usual formula:

• Sensitivity = True Positives/(True Positives + False Negatives)

• Specificity = True Negatives/(True Negatives + False Positives).

All data were tabulated and analyzed using Microsoft Excel spreadsheets. Chi-square test was used to calculate (P) value for statistical significance, while Cohen’s d was used to assess the effect size. Confidence interval (CI) was denoted as 95%.

To compensate for the disparity in the sample size between the oral and intavesical groups, we calculated the effect size for the difference in sensitivity and specificity between the oral and IV form as the effect size using Cohen’s d test. The effect size is not supposed to be affected by the sample size. In this regard, we have also highlighted the necessity of larger scale randomized controlled studies.

To minimize the inter-observer variability, all operating surgeons had a minimum identified level of operative experience with a standardized cystoscopy technique. Adverse reactions were recorded postprocedure.

RESULTS

A total of 88 participants were eligible for the study. Group A consisted of 10 patients, all of whom received the new oral (ALA Onco) powder, representing the first cohort in the Middle East and GCC countries to undergo PDD. The demographic and clinical data for this group are illustrated in Table 1. Conversely, Group B included 78 patients, all of whom received IV 5-ALA.

Table 1.

The first 10 reported cases from the Middle East and the GCC countries with the use of 5ALA Oncopowder provided by SBI-Parma Japan

First diagnosis	Age	Gender	5 ALA dose in (g)	Time to surgery in (h)	Number of tumors	Adjuvant therapy	Tumor clearance	Follow up period in (months)	3 months check outcome
No	64	Male	1.5	3	Large single	BCG MMC	Complete	18	Negative
No	60	Male	1.4	3.5	Multiple	MMC	Complete	24	Negative
Yes	60	Female	1.4	3.5	Multiple	BCG	Partial	22	Negative
Yes	55	Male	1.3	3	solitary	None	Complete	22	Negative
Yes	58	Male	1.5	4	Multiple	None	Complete	24	Negative
Yes	70	Male	1.5	3.5	Multiple	None	Complete	24	Negative
Yes	50	Male	1.5	3	Solitary	None	Complete	15	Positive
Yes	40	Male	1.4	3	Multiple	None	Complete	24	Negative
No	45	Male	1.5	3.5	Multiple	None	Partial	24	Negative
Yes	55	Female	1.5	3	Solitary	None	Complete	22	Negative

The demographic data, tumor characteristics, clearance by resection, and the follow-up outcome. MMC: Mitomycin C, BCG: Bacille Calmette–Guérin (tuberculosis vaccine), 5 ALA: 5-aminolevulinic acid

Patient demographics and clinical presentation

Further analysis of patient demographics showed a peak incidence at a younger age (60–69 years) compared to published literature. The most common presenting symptom was visible painless hematuria (77%). Other symptoms included dysuria, suprapubic masses, incidental findings on ultrasound, and lower urinary tract symptoms due to bladder neck involvement. Nearly 49% of patients had no prior history of malignancy or urethral instrumentation.

Diagnostic performance

For Group A, both the sensitivity and specificity of PDD were significantly higher than white light, as demonstrated in Figure 1. The IV route also showed higher sensitivity, with specificity values comparable to white light [Figure 2].

Figure 1.

Sensitivity and specificity of orally administered 5-aminolevulinic acid compared to white light in the detection and follow-up of bladder carcinoma (urothelial, squamous, and bilharzia related)

Figure 2.

Sensitivity and specificity of intravesically administered 5-aminolevulinic acid compared to white light in the detection and follow-up of bladder carcinoma (urothelial, squamous and bilharzia related)

Oral 5-ALA demonstrated a sensitivity of 96%, compared to 60% for white light which with a statistically significant difference (P = 0.025) with (95% CI 0.201–0.519). In terms of specificity, oral 5-ALA was statistically superior at 94%, compared to 80% with P = 0.024 (95% CI 0.160 –0.519). On the other hand, IV 5-ALA showed 85.12% sensitivity compared to 70% for white light which is statistically significant (P = 0.021) and (95% CI0.231 –0.279). There was no difference between white light and IV 5 ALA with regards to specificity (50% for both).

On direct comparison, there was a statistically significant difference in favor of the oral form in terms of specificity (P = 0.008) with (95% CI 0.256, 0.624) and a large effect size of 0.8, whereas the oral 5-ALA showed higher sensitivity with no statistical difference and small to medium effect size 0.3. The follow-up period was 15–24 months.

On subgroup analysis among nonmuscle-invasive category, PDD picked up 24% more lesions that would have been missed if white light was used alone. These lesions included CIS lesions which is a flat carcinoma that can be treated nonsurgically if diagnosed early enough. Among the muscle-invasive category, both the sensitivity and the specificity were equivalent for PDD and white light. Diagnoses within both groups were confirmed using ultrasound, computed tomography scans, and histopathological examination.

Adverse effects and recurrence

No serious side effects or adverse reactions related to 5-ALA administration were observed in either groups. However, two patients from the oral 5-ALA group experienced mild transient skin photosensitivity due to sunlight exposure.

Histopathological findings

As shown in Figure 3, 92% of tumors were transitional cell carcinomas. Notably, 10% of tumors were bilharzia-associated bladder cancer, a higher proportion than typically reported in the existing literature.

Figure 3.

The distribution of bladder tumor histological types. Around 10% are bilharzia associated

DISCUSSION

There is a high level of evidence in the current literature confirming the significant percentage of residual and recurrent disease among stage T1 bladder tumor patients detected during early check cystoscopy, even in the hands of experienced urologists.[22,23] Therefore, additional optical aids became of great value in enhancing the detection of the early stages of bladder tumors. A large body of evidence has mounted in favor of PDD in improving the detection of NMIBC and CIS,[24,25,26,27] especially after random bladder biopsies became an obsolete practice unless urine cytology is positive.[4]

A study by Inoue et al.[17] in 2011 compared the use of oral 5-ALA to IV PDD, with a design that shares some similarities to our current study as it was retrospective and focused on the diagnostic accuracy. Inoue et al. concurred with our findings of higher sensitivity of both PDD modalities when compared to conventional white light. They also reported minor adverse effects of the PDD. Another advantage of oral 5 ALA is the simultaneous detection of upper tract urothelial carcinoma due to the kidney uptake and excretion of 5 ALA.[28] A very recent study by Taoka et al.[14] reported on a group of patients who were exclusively given oral 5 ALA. The researchers suggested that oral 5-ALA may have a possible therapeutic role given the improvement in the recurrence-free survival. Of note Taoka et al. used a similar dose regimen to what we used in the current study (20 mg/kg).

In addition to its inconvenience for patients, the IV route was anecdotally postulated to negatively influence the accuracy of PDD, as the catheter dwell time was insufficient in around one-third of cases which resulted in reduced 5-ALA diffusion into the cells. Furthermore, the signal in the dome was reported to be fainter. On the other hand the wider use of oral 5-ALA is hindered by its high cost and the variability in pharmacokinetics. Nevertheless, the use of the oral form excludes the cost associated with urethral catheterization and its morbidity.

The main limitation of this study is the fact that the oral and the IV groups were dissimilar in terms of the total number of participants, which was due to the limited availability and higher cost of the oral 5-ALA. Furthermore, the study was retrospective in nature. The assessment of PDD among the morphologically non muscle invasive group and the inclusion of a considerable percentage of bilharzia-associated tumor patients were novel aspects in our study.

CONCLUSION

PDD using oral 5-ALA demonstrated superior diagnostic accuracy compared to IV instillation and white light cystoscopy along with lower recurrence rate making it the preferable option while larger-scale studies are awaited. Any further research should have randomized controlled design while focusing on the oncological outcome, patient-reported experience, and cost-effectiveness of oral and intra-vesical 5-ALA.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.