A Strategy Using Photodynamic Therapy and Clofibric Acid to Treat Peritoneal Dissemination of Ovarian Cancer

Background: The current study examined the effectiveness of concurrent therapy using photodynamic therapy (PDT) and clofibric acid (CA) to treat peritoneal carcinomatosis resulting from ovarian cancer. Materials and Methods: Nude rats were used to create a model of peritoneal carcinomatosis resulting from ovarian cancer and the effectiveness of PDT with 5-aminolevulinic acid methyl ester hydrochloride (methyl-ALA-PDT) was determined. The survival time of rats receiving that therapy was compared to the survival time of a control group. Rats with peritoneal carcinomatosis resulting from ovarian cancer were divided into 3 groups: a group that received debulking surgery (DS) alone, a group that received DS+methyl-ALA-PDT, and a group that received DS+methyl-ALA-PDT+CA. The survival time of the 3 groups was compared. Protoporphyrin, a metabolite of methyl-ALA, produces a photochemical action when activated by light. The level of protoporphyrin (the concentration) that reached organs in the abdomen was measured with HPLC. Results: Rats receiving methyl-ALA-PDT had a significantly longer survival time compared to the controls. Rats with peritoneal carcinomatosis that received DS+methyl-ALA-PDT+CA had a significantly longer survival time compared to the rats that received DS alone. Some of the rats that received concurrent therapy survived for a prolonged period. Protoporphyrin was highly concentrated in peritoneal metastases, but only small amounts reached major organs in the abdomen. PDT was not found to result in necrosis in the intestines. Conclusions: The results indicated that concurrent therapy consisting of PDT with methyl-ALA and CA is effective at treating peritoneal carcinomatosis resulting from ovarian cancer without damaging organs.