ATLANTA, Jun 01 (Reuters Health) - Prostate specific antigen (PSA) levels declined by more than 50% in all patients with androgen-dependent prostate cancer who received an herbal compound, according to findings presented at the 35th annual meeting of the American Society of Clinical Oncology.
Dr. Eric Small and colleagues at the University of California San Francisco treated 61 men, aged 43 to 90 years, with confirmed adenocarcinoma of the prostate. Twenty-seven men had androgen-dependent prostate cancer while 34 had hormone-resistant disease.
The treatment protocol involved PC-SPES, a compound that consists of eight Chinese herbs, titrated up to 960 mg t.i.d. by the third week of the study. Saw palmetto is the primary ingredient. Dr. Small notes that "PC" stands for prostate cancer and "SPES" is the Latin word for hope.
In 56% of the 27 androgen-dependent patients, PSA levels fell to undetectable levels. PSA levels fell more than 50% in all men with hormone-dependent disease, Dr. Small reported. Transrectal ultrasound showed that 8 of 16 androgen-dependent patients had a greater than 50% reduction in tumor volume with PC-SPES, he added.
Of the 34 androgen-independent patients treated with PC-SPES, 19 (56%) had a greater than 50% decline in PSA. Nearly half of patients in this group had previously undergone second-line hormone treatment, Dr. Small said. "Of these, 62% had a response to PC-SPES."
Baseline bone scans revealed that 22 of the androgen-independent patients had positive bone metastases. Of the 12 available for evaluation, Dr. Small told Reuters Health in an interview that "...two have had dramatic improvement in their bone scans."
The researchers reported mild nausea in 38% and mild leg cramps in 33% of the patients treated. Testosterone levels dropped to levels consistent with conventional hormonal therapy in 81% of the PC-SPES treated patients, and 92% of the patients reported gynecomastia.
"We think the patients do better [with PC-SPES] in terms of side effects than with conventional hormone therapy," Dr. Small said.
"This herbal treatment appears to have activity against prostate cancer, and it is promising activity," Dr. Small told Reuters Health. He acknowledged that he and his colleagues have not been able to pinpoint the estrogenic or anticancer component of PC-SPES.
Follow-up to evaluate durability of response and long-term side effects of PC-SPES treatment is under way.