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In Vivo Fluence Rate Effect in Photodynamic Therapy of Early Cancers with Tetra( m ‐hydroxyphenyl)chlorin
Author(s) -
Blant Snezana Andrejevic,
Woodtli Alain,
Wagnières Georges,
Fontolliet Charlotte,
Bergh Hubert,
Monnier Philippe
Publication year - 1996
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1996.tb01862.x
Subject(s) - photodynamic therapy , chlorin , tetra , in vivo , fluence , chemistry , cancer research , photochemistry , medicine , biology , medicinal chemistry , ion , organic chemistry , microbiology and biotechnology
Abstract— Several parameters affect clinical trials in photodynamic therapy and influence the therapeutic outcome. Beside drug dose, light dose, drug‐light interval and other variables, the fluence rate is a parameter that can influence the therapeutic results. In this study we have evaluated the fluence rate effect with a second‐generation photosensitizer, tetra( m ‐hydroxyphenyl)chlorin (mTHPC) using a 7,12‐dimethylbenz(a)anthracene induced early squamous cell carcinoma of the Syrian hamster cheek pouch as a tumor model. Following injection of 0.5 mg/kg of mTHPC, irradiation tests were performed at two drug‐light intervals, 4 and 8 days. Wavelength and light dose were adapted from those applied routinely in clinical trials. Irradiations at 652 nm were carried out with fluences ranging from 8 to 20 J/cm 2 delivered at fluence rates of 15 and 150 mW/cm 2 . Similar tests were also performed at 514 nm with a fluence of 80 J/cm 2 delivered at fluence rates ranging from 25 to 125 mW/cm 2 . At both wavelengths and drug‐light intervals for a given fluence, the higher fluence rates resulted in less tissue damage in tumor and healthy mucosae. However, the lower fluence rates yielded slightly less therapeutic selectivity. This study confirms that the fluence rate is of major importance in clinical PDT.