Anti-tumor effects of PC-SPES, an herbal formulation in prostate cancer

Prostate cancer is the most common cancer amongst males in developed countr ies. Surgical removal of the prostate effectively cures the primary disease but the metastatic disease is refractory to most forms of chemotherapy. Th ere is a clinical need to develop novel treatment strategies that exploit t he mode of action of both conventional and alternative drugs/medicinal plan ts. We have been investigating the antiproliferative and anti-tumor effects of an herbal preparation termed PC-SPES (patent pending, US serial number 08/697, 920) which is a refined powder of eight different medicinal plants. PC-SPES administered as a food supplement caused a dramatic decrease in pr ostate specific antigen levels in some prostate cancer patients with advanc ed disease. These preliminary clinical findings laid the foundation for a p rogram to examine the in vitro and in vivo effects of PC-SPES, and identify the active component in this mixture so that a standardized treatment regi men can be formulated. In this communication, we report the anti-tumor effe cts of PC-SPES incorporated in the diet utilizing a well studied Dunning R3 327 rat prostate cancer model. Dietary PC-SPES at levels of 0.05% and 0.025 % did not exhibit any toxicity and no significant difference in food intake was noted at the end of six weeks. Dose dependent inhibitory effect of die tary PC-SPES was observed on both tumor incidence (P=0.01) and rate of tumo r growth when tumors were induced in syngeneic Copenhagen rats by intraderm al injections of MAT-LyLu cells that are known to metastasize in the lung a nd lymph nodes. The number of pulmonary metastases in animals on PC-SPES th at showed no primary tumor growth had no metastatic lesions in the lung, ho wever, in animals that did not respond to PC-SPES, the number of pulmonary metastases was not significantly different from the nontreated controls. Th e significant anti-tumor effects of PC-SPES on MAT-LyLu induced tumorigenes is and metastasis in Copenhagen rats, in general refractory to most convent ional therapy, suggests a therapeutic benefit of this herbal food supplemen t and may be a useful adjuvant to conventional therapeutic modalities.