Oral shiitake (Lentinula edodes) mycelia extract strengthened the immune response to radiotherapy by increasing key tumor-fighting cells from 44% with radiation alone to 62% when combined with the extract, while shrinking tumors from ~1613 mm³ to ~632 mm³ in treated models. The extract worked through the gut, activating dendritic cells that “train” cytotoxic T cells to recognize and attack cancer more effectively. In practical terms, shiitake acted as an oral immune amplifier, helping radiation therapy trigger a stronger and more coordinated anti-tumor response.