Effect of 514.5-nm argon ion laser radiation on hematoporphyrin derivative-treated bladder tumor cells in vitro and in vivo.

The therapeutic effect of hematoporphyrin derivative (HpD) plus 514.5-nm argon ion laser radiation was compared to HpD plus 630-nm argon ion laser-pumped dye laser radiation in experimental urinary bladder transitional cell carcinoma models. Cultured human bladder cancer cells (EJ) containing HpD were 2.8-fold more sensitive to 514.5-nm radiation than to 630-nm radiation as measured by clonogenic capacity. The relative effectiveness of 514.5-nm versus 630-nm light was approximately proportional to the spectral absorbance for cell-bound HpD at these wavelengths. HpD-sensitized photoirradiation was studied in solid tumors produced by a) the subcutaneous inoculation of cells from murine bladder tumors induced by N-[4-(5-nitro-2-furyl)-2-thiazoyl]formamide (CAS: 24554-26-5) into female C3H mice (MBT-2 tumor) and b) the intravesical instillation of N-methyl-N-nitrosourea (CAS: 684-93-5) into the urinary bladders of female Wistar rats. The tumors were exposed to 144 J/cm2 laser light 24-48 hours following ip injection of 20 mg HpD/kg body weight. By 24-48 hours, animals that received HpD and light of either wavelength had partially or completely necrosed tumors. Control groups showed no necrotic changes. Regression of MBT-2 tumors was also investigated. Seven of 14 and 6 of 12 animals had nonpalpable tumors 1 week after treatment with 514.5-nm and 630-nm light, respectively. Tumors in control groups demonstrated no regression. Spectral transmittance from 630 nm to 514.5 nm decreased by about 4% for 130- to 160-micron-thick sections of canine urothelium and bladder submucosa-muscularis. The results of this study indicate that HpD plus 514.5-nm laser radiation may be an effective treatment for small or superficial malignant lesions of the urinary bladder.