Phellinus linteus is a medicinal mushroom traditionally used in East Asian countries for its purported health benefits, including immune support. In the context of chemotherapy, there is some preliminary scientific evidence suggesting that Phellinus linteus extracts may help reduce side effects associated with cancer treatment, such as immunosuppression and fatigue. Laboratory and animal studies have demonstrated that its polysaccharides and other bioactive compounds can modulate immune responses by stimulating macrophage activity and enhancing cytokine production. In limited clinical research, small studies and case reports have explored its adjunctive use in cancer patients, suggesting potential improvements in quality of life and reductions in chemotherapy-induced side effects. However, these studies are often not well controlled or are too small in scale to draw definitive conclusions.

Most of the current evidence comes from in vitro and animal models, with a few early-phase human trials. As a result, while there is scientific interest and some validation for its use as a supportive therapy during chemotherapy, the evidence is not robust or consistent enough to recommend it as a standard adjunct treatment. Further large-scale, placebo-controlled clinical trials are needed to fully establish efficacy and safety. Until then, its use should be considered experimental and discussed with healthcare providers.