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PC-SPES Effects on Patients With Androgen Dependent Prostate Cancer
FROM ASCO 2000 asco online genitourinary cancer
New York. May 20, 2000 -- PC-SPES, a mixture of eight herbs sold as a nutritional supplement for the treatment of prostate cancer, has been shown to have estrogenic activity, although other mechanisms of activity have been reported.
Investigators at University of San Francisco, CA. and Memorial Sloan-Kettering, New York have studied the efficacy and toxicity of PC-SPES in two groups of prostate cancer patients showing disease progression. One group was made up of men with hormone naive cancer and normal testosterone levels. The others had taken hormonal therapy and had developed androgen independent disease.
Effects of the herbs on the hormone "naive" men summarized below were tabulated for this year's ASCO meeting. Results from this trial on men resistant to hormonal therapy will follow. A report from Dana-Farber indicates responses of 2-3 months.
Thirty-three patients with hormone naive prostate cancer were treated with PC-SPES. Patients received 9 capsules a day of PC-SPES. Median follow-up is 50 weeks. Median PSA was 7.9 (ranging from 0.9 to 81).
Thirteen of the 33 patients had untreated localized disease, 12 had local recurrence, 5 PSA only recurrence, and 2 untreated bone metastases.
PSA fell by more than 80% in 100% of patients, and to undetectable in 21 out of 33 (64%).
The median duration of PSA decline was 46.5 weeks+, and no patient has come off therapy because of disease progression.
Fourteen out of 19 patients (74%) who had disease assessable by transrectal ultrasound (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 below 50ng/ml in 31 patients out of 33 (94%). Of twenty five patients who had libido (sexual desire) on entering the study, all twenty-five lost libido with therapy, and fifteen out of 15 patients who were potent at study entry lost potency.
Breast swelling and tenderness was observed in 100% of patients.
Two out of 33 patients (6%) experienced a deep vein thrombosis (DVT).
Grade 1,2 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).
PC-SPES, the researchers conclude "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." This is consistent with earlier reports.
Related Links
ASCO abstract 11316 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, William F. Kelly, David M. Reese, Univ of CA, San Francisco, CA; Memorial Sloan-Kettering, New York, NY.
ASCO Report from Dana-Farber on effects of PC-SPES on men who have already become resistant to conventional hormonal blockade
Earlier PC-SPES Update -- May 6- July 9, 1999PC-SPES website http://www.pc-spes.com
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