Out of Korea comes a new and increasingly popular medicinal mushroom known as Phellinus linteus. It does have a rarely used English common name, Black Hoof Fungus. But you are more likely to hear it referred to by its Japanese name as Mesima.
Common to southern United States and Southeast Asia, Phellinus linteus is a polypore on hardwood trees such as poplar, oak and mulberry. 
Unlike most medicinal mushroom species, which were originally used in China or Japan, Phellinus linteus first became popular in Korea as a complement to traditional cancer therapies such as radiation and chemotherapy.
The reputation of Phellinus linteus as a powerful medicinal mushroom has rapidly spread across the world and today it is increasingly popular with medical professionals from the U.S. and Japan to Turkey and Israel as an immune booster [2-11], especially for the prevention of cancer metastasis. [5,10,12-17]
Perhaps it all got started when one of the first Korean studies on Phellinus linteus in 1996 reported that it exhibited a wider range of immunostimulation and antitumor activity than polysaccharides isolated from other medicinal mushroom species. 
Years later, American world-renown mycologist Paul Stamets helped deepen our understanding of Phellinus linteus when he published a comparative analysis with the most common medicinal mushroom species: Agaricus blazei, Lion's Mane, Chaga, Reishi, Maitake and Cordyceps. 
Among the seven species of medicinal mushrooms compared in this study, Phellinus linteus had the most powerful effect on enhancing macrophage activity, by 5,700%. Macrophages are an important part of the immune system's cancer fighting arsenal. The amount of Phellinus linteus extract used was equal to 3,750 mg for an adult of average weight (165 lbs). 
Although human macrophage cells have been known to both induce and inhibit cancer growth, the published research on Phellinus linteus shows that it promotes the anti-cancer properties of macrophages rather than their potential cancer-inducing properties. [8,14,19,20]
In addition to these studies, there are at least three published cases of spontaneous regression of cancers after patients of their own accord used Phellinus linteus extract:
1. A 2004 paper out of Japan reported "a hormone refractory prostate cancer patient with rapidly progressive bone metastasis who showed dramatic response to intake of an extract from the mushroom, Phellinus linteus." 
2. A Korean journal published a paper in 2005 which reported on a "spontaneous regression of a large hepatocellular carcinoma with skull metastasis." The 65-year-old patient had "ingested mushroom called Phellinus linteus for one and a half years." 
3. Finally, an article published 2006 in the Japanese journal Radiation Medicine told of a "patient with hepatocellular carcinoma with multiple lung metastases in whom malignancy spontaneously regressed after taking Phellinus linteus Mycelium." The 79-year old patient reportedly "took extract from Phellinus linteus Mycelium for one month, and 6 months later the tumors appeared to be in complete regression." 
This article is for informational purposes only. It is not intended to diagnose, treat, cure or prevent any disease. The mushroom Phellinus linteus has not been approved by the FDA for medicinal use. Always consult a licensed medical practitioner before using any herb or mushroom medicinally.