Protoporphyrin IX induced by 5-aminolevulinic acid in bladder cancer cells in voided urine can be extracorporeally quantified using a spectrophotometer.

We evaluated the feasibility of photodynamic diagnosis of bladder cancer by spectrophotometric analysis of voided urine samples after extracorporeal treatment with 5-aminolevulinic acid (ALA). Sixty-one patients with bladder cancer, confirmed histologically after the transurethral resection of a bladder tumor, were recruited as the bladder cancer group, and 50 outpatients without history of urothelial carcinoma or cancer-related findings were recruited as the control group. Half of the voided urine sample was incubated with ALA (ALA-treated sample), and the rest was incubated without treatment (ALA-untreated sample). For detecting cellular protoporphyrin IX levels, intensity of the samples at the excitation wavelength of 405 nm was measured using a spectrophotometer. The difference between the intensity of the ALA-treated and ALA-untreated samples at 635 nm was calculated. The differences in the bladder cancer group were significantly greater than those in the control group (p < 0.001). These differences were also significantly greater in patients with high-grade tumors than in those with low-grade tumors (p = 0.004), and also in patients with invasive bladder cancer than in those with noninvasive bladder cancer (p = 0.007). The area under the curve was 0.84. Sensitivity and specificity of the method were 82% and 80%, respectively. We demonstrated that protoporphyrin IX levels in urinary cells treated with ALA could be quantitatively detected by spectrophotometer in patients with bladder cancer. Therefore, this cancer detection system has a potential for clinical use.