While the cornerstone of managing patients with nonmuscle invasive bladder cancer (NMIBC) is white light (WL) cystoscopy with transurethral resection of bladder tumor (TURBT), WL cystoscopy has limited accuracy in differentiating benign from malignant lesions, particularly in the case of carcinoma in situ.¹ Blue light (BL) cystoscopy (BLC) utilizes preoperative instillation of protoporphyrins that accumulate in neoplastic cells and provide differential fluorescence at wavelengths of 360–450 nm. BLC has been shown to improve the detection of bladder tumors and its use is associated with improved clinical outcomes.²

BLC was approved for use in the United States in 2010 and is recommended by many society guidelines. Despite this, the clinical uptake of BLC since its approval has been limited. As of 2019 there are only 233 BL platforms installed in the U.S.³ While the widespread use of BLC may be hindered by several factors including initial capital investment, training and practical obstacles including the need for prolonged instillation time, there are limited data regarding how practicing urologists perceive the clinical usefulness of BLC. A recent publication in Urology Practice^® by Stout et al evaluated the perceived clinical utility of BLC for the perspective of practicing urologists.⁴ This study also evaluated changes in attitudes towards BLC over time and assessed factors associated with higher perceived utility.

Methods

Patients from 14 institutions across the U.S. with known or suspected NMIBC were included in the study, which took place from 2014–2019. Patients underwent rigid cystoscopy with BL and WL and all suspicious lesions were resected. Immediately following cystoscopy, the participating urologist assessed the utility of BLC in that specific case on a 4-point scale, with response options including 1–“of no real clinical utility over standard WL,” 2–“of some clinical utility over standard WL,” 3–“of moderate assistance over WL” or 4–“essential for identification and/or elimination of lesions that would otherwise have been missed by standard WL.” Outcomes included the perceived clinical utility among high-volume and low-volume urologists, changes in perceived utility over time and factors associated with high perceived clinical utility (defined by a rating of 3 or 4 on the 4-point scale).

Results and Discussion

Over the course of the 6-year study period, 1,702 cystoscopies were performed by 65 urologists in 1,336 patients. Of the cystoscopies 67% were performed in patients with recurrent disease and, not surprisingly, the majority (65%) had received prior intravesical therapy. Of the 3,771 lesions biopsied 60.6% were identified on both WL and BL, followed by 23% identified with BL only and 11.2% identified with WL only. Among all post-cystoscopy surveys, urologists perceived BLC to be of some utility (38.1%), moderate assistance (25.4%), essential (19%) and no real utility (17.5%).

Figure 1. Perceived utility of BLC over time among 1,243 low-volume users (A) and 459 high-volume users (B).

Figure 2. Multivariable logistic regression of factors associated with high perceived utility of BLC (rating BLC to be either of moderate assistance or essential).

The percentage of users who perceived BLC to be essential significantly increased from 11.5% in 2014 to 28.3% in 2019 (p=0.006). Due to the learning curve associated with BLC, it was proposed that the perceived utility of BLC may be higher in high-volume urologists (upper quartile of the number of BLC performed) compared to low-volume urologists (lower 3 quartiles). There was no significant change in perceived utility among low-volume urologists over the study period (p=0.227; fig. 1, A). Among high-volume urologists, however, there was significantly higher perceived utility over time (p = 0.013). In 2017, 34.0% of high-volume urologists perceived BLC to be of moderate assistance or essential, and this increased to 55.2% by 2019 (fig. 1, B). On multivariable regression factors associated with a significantly higher perceived utility were more lesions seen only with BLC (LR 4.88, CI 2.27–8.78), malignant pathology from biopsies taken during the cystoscopy (LR 3.31, CI 2.10–5.23) and total number of lesions seen with BLC (LR 1.36, CI 1.19–1.55; fig 2).

In 1,702 rigid BLCs, this study found that the perceived clinical utility of BLC has been increasing over time, particularly among high-volume urologists. As high-volume urologists likely have the greatest proficiency with BLC they can better utilize the technology and find it more clinically useful. Urologists who identify more lesions with BLC, particularly if such lesions are only visible on BL, also find BLC to be more helpful. To increase uptake of BLC across the U.S., efforts should be placed towards adequately training urologists to best utilize the technology, as that will hopefully increase perceived utility, and therefore adoption into clinical practice.