Abstract
Experiments were performed on six batches of Wistar inbred rats with Walker-256 carcinosarcoma 7 days post-transplantation. Animals from batches I and II were exposed to photofrin II (20 mg/kg body mass) or HeNe laser (10 mW; 632.8 nm), respectively; the animals in the batches III-V were given photofrin II, intraperitoneally, 24 h before 60-min laser treatment; one, three and six photofrin/laser treatments, respectively, were applied at an interval of 3 days. The control batch (batch VI) consisted of animals presenting with untreated Walker-256 tumours. The results were as follows: photofrin II or HeNe laser alone (photoexposure to low doses of 15 J/cm2) had no significant effects on tumoural volume and the survival of the rats. Photoexposure to multiple doses of PDT led to complete regression of tumoural volume (65.8%); the cure rate was 31.5% and concomitantly survival rates increased, Cell-mediated immunity tests (performed at 7 and 28 days post-treatment) underlined superior values in batch IV and V animals photoexposed to multiple PDT doses, in comparison with immuno-suppression noticed in batches I-III and the control batch VI. Data presented in this work demonstrate that photodynamic treatment exposure using multiple doses stimulates cell-mediated antitumoural activity. Induces modifications in tumoural histological structure, increases survival rates and reduces tumoural incidence in Walker-256 carcinosarcoma in the rat model.
