Effects of PC-SPES, an Herbal Compound, in Patients with Androgen Dependent Prostate Cancer
Eric J. Small, Michele Corry, Mark A.
Frohlich, Robert A. Bok, Katsuto Shinohara,
INTRODUCTION -- PC-SPES, a nutritional supplement consisting of 8 different herbs used for the treatment of prostate cancer, has been shown to have estrogenic activity, although other mechanisms of activity have been reported.
METHODS -- We studied the efficacy and toxicity of PC-SPES in two cohorts of prostate cancer patients demonstrating disease progression: a) hormone naive patients with normal testosterone levels (the basis of this report), and b) androgen independent patients. Thirty-three patients with hormone na´ve prostate cancer were treated. Patients received 9 capsules a day of PC-SPES. Median follow-up is 50 weeks. Median PSA was 7.9 (0.9-81). Thirteen patients had untreated localized disease, 12 had local recurrence, 5 PSA only recurrence, and 2 untreated bone metastases.
RESULTS -- PSA fell by more than 80% in 100% of patients, and to undetectable in 21/33 (64%). The median duration of PSA decline was 46.5 weeks+, and no patient has come off therapy because of disease progression. 14/19 patients (74%) who had disease assessable by TRUS had significant (greater than 50%) decrease in tumor volume. Of 2 patients with positive bone scans, 1 improved and 1 was stable. Testosterone levels declined to < 50ng/ml in 31/33 (94%). 25/25 patients with libido present at study entry lost libido with therapy, and 15/15 patients who were potent at study entry lost potency. Gynecomastia/gynecodymia was observed in 100% of patients. 2/33 patients (6%) experienced a deep vein thrombosis. Grade1,2 diarrhea was seen in 33%, and leg cramps in 64%. Five patients have come off therapy (2 for DVT, 1 for breast tenderness, 1 for leg cramps, and 1 to pursue definitive local therapy).
CONCLUSIONS -- PC-SPES is able to produce ongoing lasting PSA declines in virtually all patients with hormone naive prostate cancer. In some patients a decline in PSA correlates with objective measures of tumor response. Testosterone declines and side effect profile suggest that the mechanism of action is estrogenic in nature.