INTRAPERITONEAL PHOTODYNAMIC THERAPY OF THE RAT CC531 ADENOCARCINOMA

The goal of this study was to investigate the efficacy of photodynamic therapy (PDT) of a single tumour growing intraperitoneally. For this purpose the CC531 colon carcinoma, implanted in an intraperitoneal fat pad of Wag/RijA rats, was treated with intraperitoneal photodynamic t herapy (IPPDT) using Photofrin as the photosensitiser. Two illuminatio n techniques have been compared. An invasive illumination technique us ing Perspex blocks to illuminate 30 cm(2) of the lower abdomen gave a significant delay in tumour growth with 25 J cm(-2) applied 1 day afte r Photofrin. A minimally invasive illumination technique using a ballo on catheter to illuminate 14 cm(2) resulted in an equivalent growth de lay with 75 J cm(-2). The route of administration of the photosensitis er did not influence regrowth times of the tumour. Mitomycin C (MMC), a bioreductive agent, was used to exploit the known PDT-induced hypoxi a. The combination of IPPDT with MMC resulted in an increased tumorici dal effect. In conclusion, IPPDT led to a significant growth delay for a single tumour implanted intraperitoneally and repetition of the PDT treatment was possible using a minimally invasive illumination techni que. Repeated treatments resulted in increased tumour response.