INTRODUCTION/OBJECTIVES: PC-SPES is an herbal mixture available over the counter for the treatment of prostate cancer. It was re-called in January 2002 due to alleged contamination with warfarin. Other laboratories, including our own, claim that the potent synthetic estrogen, diethylstilbestrol (DES) which has been used for many years to treat hormone dependent prostate cancer, could be detected in the herbal mixture. Recent clinical studies report objective responses in men with hormone dependent and na?ve prostate cancer, and also describe isolated cases of estrogenic side effects. A lack of effective conventional treatments for advanced hormone refractory prostate cancer has led to a widespread use of PC-SPES by patients across the North America continent. The presence of DES in PC-SPES might explain both clinical response and observed side effects in men taking 6-9 capsules per day.
METHODS: We tested five batches of commercially available PC-SPES using gas chromatography (GC) and high performance liquid chromatography (HPLC) upon methanolic extraction. Duplicate aliquots were tested for each batch and the results compared to standard curves generated using DES (99% purity).
RESULTS AND CONCLUSIONS: We detected significant levels of DES in three out of five tested batches. The presence of a synthetic steroid in PC-SPES is not likely to have occurred as a result of its extraction from a herbal source. The implications of this finding highlight the necessity of regulated quality control and standardization of natural health products.