Evaluation of ALA-PDT of ovarian cancer in the Fisher 344 rat tumor model

SummaryObjectiveThis study aimed to evaluate aminolevulinic acid-photodynamic therapy (ALA-PDT) in an experimental tumor model to expand the use of PDT in the treatment of ovarian cancer with peritoneal carcinosis.Materials and methods5-Aminolevulinic acid (ALA) (Photocure ASA, Norway) 60 mg/kg was injected in the peritoneum cavity of 45 female rats Fisher with induced peritoneal metastases of ovarian cancer. ALA-PDT was performed 4 h later with two different lasers: (1) laser diode (Diomed, Cambridge, UK), at 630 nm, 100 mW/cm2, or (2) KTP laser (Laser Quantum, Stockport, UK), 532 nm, 30 mW/cm2. The animals were divided into five groups: LASER ALONE group, CTRL group (no cancer), NO LASER group, 1 DOSE group (PDT during 1 s) and 1.5 DOSE group (PDT during 1.5 s). Biopsies were taken 24 h after treatment. A semi-quantitative score called necrosis value (NV) was assigned to each sample that reflected the depth of the peritoneal necrosis.ResultsIn the first two groups, the peritoneum remained intact irrespective of the wavelength. In the 1 DOSE group, necrosis was observed for 532 nm and 630 nm. In the 1.5 DOSE group, necrosis was observed for 532 nm (NV: 3.22 ± 0.83) and 630 nm (NV: 2.67 ± 1.00) (p < 0.05). The mesothelium strongly thinned out in the diffuse shape of the tumor.ConclusionOnly ALA-PDT induces tumor necrosis with either 532 nm and 630 nm and should be considered an effective therapy for micrometastasis of ovarian cancer. This preliminary study deserves further experiments.