A number of studies suggest that turkey tail mushroom (Trametes versicolor) shows promise as a complementary treatment for people with cancer. In 2012, a small phase I clinical trial looked at the effects of turkey tail mushrooms on nine women with stages I-III breast cancer who had completed radiation therapy or chemotherapy. Results showed that immune function was enhanced in those who took daily doses of turkey tail in pill form. (The actual product used in the study was Host Defense Turkey Tail from Fungi Perfecti.) The researchers reported that the improved immune response was dose dependent and that none of the subjects suffered any adverse effects.