Abstract

The effectiveness of photodynamic therapy (PDT) as an adjuvant treatment for diverse malignant tumors has been investigated in numerous studies. The therapeutic success and extent of side effects of PDT is mainly determined by the applied photosensitizer (PS) and laser energy. Adjuvant intraoperative photodynamic therapy (AIOPDT) using the PS mTHPC (meso-Tetrahydroxyphenylchlorin) causes selective tumor cell death when combined with laser irradiation of a PS specific wavelength (652 nm). Our study proved AIOPDT as an efficient modality to significantly increase postoperative recurrence-free survival after R1/R2 resection of a subcutaneously implanted soft tissue sarcoma in mice. We used mTHPC in a dose of (0,3 mg/kg BW) and a laser light energy of 5 Joule (irradiation time: 50 seconds). First results showed an increase of postoperative recurrence-free survival (Median: 103 days) in 5 animals treated with AIOPDT compared to a control group of 7 animals (Median: 20 days). The tissue specific accumulation of mTHPC was determined by point spectrofluorometry and showed a 2.28 higher PS-accumulation in the tumor center, tumor bed (1.5) and overlying skin (3.8) compared to muscle tissue (1.0) as reference parameter. Our first experimental data recommend AIOPDT to be an efficient adjuvant method to prolonge recurrence-free survival after tumor resection.

© 2001 OSA/SPIE