The blend of eight herbs, used by an estimated 10,000 men and sold over the counter, appears to reduce signs of tumor growth in patients who have exhausted all conventional treatments, according to studies in two well-regarded medical journals. The new studies, including one by Katz, on the effect of the supplement are almost certain to spark widespread demand. Almost 180,000 new cases of prostate cancer are diagnosed each year in the United States, with 40,000 deaths. The product's potency, and the likelihood that its use will grow, sharply highlight the disparity between the heavy regulation that traditional drugs undergo and the virtual absence of regulation of supplements. But for something like this, we have no oversight.
Physicians are also worried because the supplement carries the risk of serious side effects.
Most common are breast tenderness and enlargement because of herbs that act like estrogen. Similar results, reported by Small, will appear in the November issue of the Journal of Clinical Oncology. Although there have been a handful of earlier papers on PC SPES, the two new studies are the first to examine the product in a large number of men. Both studies also found that the herbal remedy reduced prostate specific antigen levels in men who had received hormone therapy, a standard approach to halt advanced disease, but who were still experiencing cancer growth. There is a subset of patients where the hormone therapy does not work and the cancer continues to grow.