Used in photodynamic diagnosis of bladder cancer, hexaminolevulinate hydrochloride is administered directly into the bladder during cystoscopy. It leads to the accumulation of fluorescent compounds in cancerous cells. When exposed to blue light, these cells emit a red fluorescence, making tumors easier to detect compared to standard white-light cystoscopy. This improves the accuracy of tumor identification, especially for non-muscle-invasive cancers, leading to more complete resection and reduced recurrence rates. It is particularly effective in detecting carcinoma in situ, which is often difficult to visualize with conventional methods.