Lasers in Surgery and Medicine 12:114 (1992)
“Photodynamic Therapy in Gastrointestinal Cancer”
4.Hp almost always contains ‘active’ oligomeric porphyrins similar t o those in Photofrin, the standard sensitizer for PDT; 5. The injected dose is 2.5 t o 5.0 times that The above paper by S. Karanov, M. Shopova used in most PDT clinical trials. and H. Getov (LSM 11:395-398, 1991) describes I believe this latter point is correct, since I the use of ‘pure’hematoporphyrin (Hp)to treat six had t o interpret the injected dose 5.1OP6 kg/kg patients with early stage G.I. tumors by PDT. The b.w. t o 5 mg/kg b.w. and the concentration source of the Hp is the same as that reported pre- 5O.1Op6 kg-70.1OP3 1t o 50 mg per 70 ml. Surely viously in certain clinical trials (L. Corti, L. To- it would have been better had the authors used mio, F. Calzavara, et al., Photodynamic Therapy standard units of mg/ml for concentration and of Tumors and Other Diseases, ed. G. Jori and C. mg/kg b.w. for injected dose. Perria, Liberia Progetto Editore Padova, pp 317Also, the dosimetry is impossible to interpret 320, 1985) and almost certainly not ‘pure’. I base as well. Did the investigators really use 0.32 to this on the following: 0.40 kJ/m2, or 0.032 to 0.04 J/cm2 t o treat these 1. No analysis or other verification of purity tumors? This is at least two orders of magnitude of the Hp is provided; less than used typically. No power density is 2. Hp is almost never obtained pure unless stated; total power from the fiber tip as stated in stringent purification steps are used and the ma- this paper is not useful without an area measureterial is stored properly and not degraded when ment to convert to power per unit area. solubilized; Corrections or clarification of this paper 3. Pure Hp is a very ineffective photosensi- would be helpful. tizer as we have shown previously (T. Dougherty, T.J . Dougherty Hematoporphyrin as a Photosensitizer of Tumors. Roswell Park Cancer Institute Photochem. Photobiol. 38:377-379, 1983); Buffalo, New York
0 1992 Wiley-Liss, h e .