Objectives: To determine whether supplemental amounts of a polysaccharide/oligosaccharide complex obtained from a shiitake mushroom extract (SME) would lower the prostate-specific antigen (PSA) level in patients with prostate cancer.
Methods: A total of 62 men (mean age 73.2 years, range 53.6 to 85.5) with histologically proven prostate cancer who had two consecutive elevated PSA readings were accrued to the study during a 3-month period. This was an open-label study in which the patients received oral administration of capsules containing SME given three times daily for 6 months. The endpoint for the trial was the lowering of the PSA levels.
Results: Of the 62 men enrolled in the study, 61 were assessable. At 4 months, 1 patient withdrew because of unrelated surgery and 7 withdrew because of disease progression; none had responded with a decrease of greater than 50% in the PSA level. By 6 months, a total of 23 patients had progression and none had responded. Thirty-eight patients had stable PSA levels after 6 months. Although not the primary endpoint of the study, in other studies these patients could have been included as responders. When the patients' rates of PSA rise before study entry were analyzed, 4 (7%) had stabilized disease while taking SME. Thus, the final results for our study patients were 0 with a complete response, 0 with a partial response, 4 (7%) with stable disease, and 23 of 61 with progression while taking SME.
Conclusions: SME alone is ineffective in the treatment of clinical prostate cancer.