Now I'll give you a heads up here -- I'm not a health professional. However, I have a vested interest in anything that is used to fight cancer cells. Doesn't everyone know someone with cancer these days?
My son is an acupuncturist and he is also someone who has researched the health benefits of local plants and fungi. Mushrooms, especially certain kinds, he tells me, are good at boosting your immune system and can even be used in an anti-cancer diet when you are facing the dreaded disease.
The man in the "How to Grow Gourmet Mushrooms" video says that some mushrooms kill cancer cells. I can't say for sure whether that statement is true, but in my way of looking at things, if you can alter your diet to promote good health, you'd be foolish not to at least try that method, even if you are receiving medical treatments.
Of course, if you have cancer, you'd want to check with your doctor first to make sure whatever natural methods you are using to combat the disease don't interfere with whatever pharmaceuticals you are taking. Some substances may interact, as plants can have powerful agents in them, too.
Mushrooms, however, so I am told, do not cause a problem in this way, but as I've said already, be sure to check with your doctor before you mess around too much. I had a friend once who almost died because he didn't inform his doctor he was taking herbal supplements and there was a drug interaction that he wasn't expecting.