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Turkey Tail Mushroom Mycelium Is Safe and May Enhance Immune Response in Women with Breast Cancer in Phase I Trial

Reviewed: Torkelson CJ, Sweet E, Martzen MR, et al. Phase I clinical trial of Trametes versicolor in women with breast cancer. Oncology. May 30, 2012; [epub ahead of print]. doi:10.5402/2012/251632.

The mushroom known as turkey tail (Trametes versicolor, Polyporaceae; referred to as Tv below) is prevalent in traditional Asian medicine. Hot-water extracts of turkey tail fruitbody containing various polysaccharides have been shown to be active against a number of cancers and are commonly used by cancer patients in Japan. Also, Tv mycelium-based products are sometimes prescribed to breast cancer patients in the United States by physicians trained in botanical medicine. Previous studies have suggested that the immunomodulatory mechanisms of action of Tv include Toll-like receptor agonist activity, the alleviation of immune-system dampening as a result of cancer treatment, immune system amplification, and defeating tumor tolerance of antigens.

Recent studies have suggested that breast cancer patients undergoing chemotherapy, surgery, and radiation treatment (RT) also suffer from a compromised immune system; thus, the investigation of treatment effects on the immune system may lead to the discovery of adjuvant agents that enhance the immune response to cancer. This dose-escalation study in breast cancer patients — who had completed surgery and chemotherapy and were about to begin radiation treatment — addressed the safety and tolerability of Tv use.

This study was conducted at the Cancer Center at the University of Minnesota in Minneapolis, MN, and Bastyr University in Kenmore, WA. Enrolled patients were women between 21 and 75 years old, diagnosed with stages I-III breast cancer, who had completed surgery and chemotherapy and were about to begin RT. Participants had normal laboratory values at baseline and agreed to avoid taking mushrooms and immunomodulatory herbs during the study. In total, 11 women were enrolled in the study; 2 women dropped out due to transportation problems, leaving 9 women who completed the study. The patients were between 38 and 68 years of age with both estrogen receptor (ER) negative and ER positive stage I-III breast cancer, and one patient did not have chemotherapy treatment before radiation.

In this study, the primary outcomes were the safety and tolerability of Tv use for breast cancer patients after RT. Adverse side effects were reported each week by patients during clinical visits or by telephone. Secondary outcomes were the comparison of pre- and post-radiation concentrations of immune system markers including complete blood count, natural killer (NK) cell activity, T/B/NK cell subset assay, phagocytic index, and cytokine concentrations. Where possible, the authors combined the data from this Tv study with data from a separate observational study (n=14) to increase sample size to n=23.1 The paper notes that the inclusion criteria for the 2 studies are identical.

The freeze-dried, powdered turkey tail mycelium was produced by Fungi Perfecti, Inc. in Olympia, WA, a leading producer of fungal extracts and preparations. The Tv capsules (500 mg) were processed by Beehive Botanicals; Hayward, WI. Patients took 3 g, 6 g, or 9 g per day in 2 daily doses with a total of n=3 in each dosage group. After finishing radiation treatment, patients began the 9-week study consisting of 6 weeks of treatment and 3 weeks of wash-out. Patients were asked to attend 6 clinical visits; the first visit served as a baseline and occurred before radiation treatment. The second visit was after the RT was completed, and the remaining visits were 2 weeks apart with the final visit occurring at the end of the wash-out period.

In total, 7 mild, 1 moderate, and 1 severe (anxiety attack) adverse side effects were reported. These included heartburn, chest pain, and cold and flu symptoms. Notably, no nausea was observed despite being reported previously from fruitbody-based extracts. Red blood cell, hemoglobin, hemocrit, white blood cell, and neutrophil counts were at normal concentrations both before and after RT; however, NK activity decreased significantly after RT (19.941 ± 18.959 lytic units [LU] vs. 9.872 ± 13.454 LU, P=0.043). The lymphocyte count also decreased in all patients (n=23) after RT (1.027 ± 0.298 cells vs. 0.681 ± 0.254 cells, P<0.001). After 2 weeks of Tv treatment, the 9 g dosage group had significantly more lymphocytes than the observational group (P<0.042).

Only the immunological markers of the dose-responsive patients were assessed (n=9). The CD8+ cytotoxic T cells (lymphocytes) were significantly greater in the 9 g dosage group as compared with the 3 g and 6 g groups (P=0.0003). In addition, CD19+ B cells (lymphocytes) were significantly greater in the 6 g group as compared to the 3 g group (P=0.0334). The actual cell count of CD16+56+NK cells did not significantly change in response to either RT or Tv supplementation, despite the decrease of NK cell activity after RT.

This study shows that Tv dosages of 3 g, 6 g, and 9 g daily are generally safe and tolerable in breast cancer patients with few moderate or severe adverse side effects. In addition, this study reports a decrease in immune system markers (lymphocyte counts and NK cell activity) after RT, suggesting a dampening effect of this treatment. Patients taking 9 g of Tv showed a significant increase in lymphocyte numbers, and those taking 6 g trended towards an increase. These findings suggest that a daily Tv dosage of 6 g and 9 g may be worthy of further investigation for immune support in breast cancer patients.

There are a few methodological problems with this study. Primarily, the statistics used to analyze the immune markers are not well described, and there are no figure legends to clarify specifics of the data presented. Also, a one-way analysis of variance (ANOVA) was used to analyze the different dosages at various time points; a 2-way ANOVA would have been more appropriate, as there is no mention that the duration of treatment was taken into account in the analysis. A second criticism is the inclusion of historic controls. The 14 subjects in the observational study were not recruited or analyzed as an arm of the present dose-response study, making the combination and comparison of these data questionable. Also, adverse side effects will need to be assessed with a larger sample size. Despite these problems, this study suggests a rationale for the relative safety of Tv as a potential adjuvant for breast cancer treatment that should be studied in more rigorous, randomized, placebo-controlled trials designed to assess the efficacy of Tv in supporting immune system function in breast cancer patients.

—Amy C. Keller, PhD


  1. Standish LJ, Torkelson C, Hamill FA, et al. Immune defects in breast cancer patients after radiotherapy. J Soc Integr Oncol. 2008;6(3):110-121.