Role of blue light cystoscopy to detect bladder cancer
"Numerous clinical studies have exhibited significantly improved tumor detection rates with BLC," write Zachary L. Smith, MD, and Norm D. Smith, MD.
Photographs courtesy of Zachary L. Smith, MD, and Norm D. Smith, MD
Transurethral resection of bladder tumor (TURBT) is one of the most frequently performed procedures by urologists. However, for such a common procedure, rates of residual/understaged disease on restaging TURBT are startlingly high. Additionally, there remain high rates of persistent disease following intravesical therapy in those who did not receive a restaging TURBT. Both of these findings raise questions over the quality of TURBT many patients are receiving.
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Accordingly, great effort has been put forth to develop more advanced techniques for the detection and eradication of tumors. Blue light cystoscopy (BLC) is one such technique, and carries many benefits over the historical standard of care, white light cystoscopy (WLC). Currently, the joint AUA and Society of Urologic Oncology (SUO) guidelines on nonmuscle-invasive bladder cancer (NMIBC) recommend offering BLC to all patients with NMIBC.
How BLC works
BLC involves instillation of a photosensitizer into the bladder prior to cystoscopy. This photosensitizer induces accumulation of protoporphyrins in rapidly proliferating cells (ie, malignant tumor cells). These protoporphyrins are then converted to photoactive porphyrins, which fluoresce red when illuminated with blue light (wavelength of 360–450 nm) (figure). Despite the multiple photosensitizing agents evaluated in clinical studies, the only agent currently approved for use in the United States by the FDA is hexaminolevulinate (HAL, marketed as Cysview).
Improved detection of tumors
Numerous clinical studies have exhibited significantly improved tumor detection rates with BLC. Meta-analyses and systematic reviews reveal a 7% to 29% increased rate of identifying small papillary tumors with BLC over WLC alone
However, the increased detection is substantially improved with carcinoma in situ (CIS), with a 15% to 41% increased rate of detection over WLC alone