Photodynamic therapy of colorectal cancer using a new light source: from in vitro studies to a patient treatment

Abstract

Photodynamic therapy (PDT) is a relatively new alternative modality for palliation of rectal cancer. We evaluate a new light source for PDT. In vitro PDT: CT26 murine colon carcinoma cells were incubated with aluminum phthalocyanine (AlPcS4) for 48 hours, subjected to photoradiation using Versa-Light and viability was assessed. There was a significant decrease in viability of treated cells as compared with controls. In vivo PDT: Balb/C mice were injected either subcutaneously or intrarectally with CT26 cancer cells. IP AlPcS4 2.5 mg/kg was injected when tumors were visible. After 24 hours mice were subjected to photoradiation. Massive tumor necrosis in response to PDT was observed. PDT also prolonged survival of the treated mice. Patient treatment: A 70 year old woman with recurrent local rectal carcinoma received IV Photofrin II 2 mg/kg. After 48 and 96 hours she was subjected to direct photoradiation. After the first light session there was complete macroscopic disappearance of the tumor. Biopsies up to 10 weeks after the treatment showed no cancer cells in the treated area. We believe that Versa-Light is a good light source for PDT. It was effective in both in-vitro and animal studies. It can also be safely used for clinical PDT.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.