Aren't mushrooms fungus, a growing environment for growing cancer???

Answer 1

Yes. "Mushrooms" are the sporulating 'cap and stalk' structure of agaricales, an order of fungi.
However any cancer causing agents that are made by mushrooms is rare. Monomethyhydrazine (MMH) from certain Gyromitras is about the only possible carcinogen that comes to mind.

But as an environment for other carcinogens to land, live and breed is not something that sounds likely at all. Carcinogens aren't a living organism that roots and breeds. "Cancer" is a general term for a vast number of conditions where ones own cells multiply out of sequence with surrounding tissue, living longer than usual and forming lumps of tissue that spread and eventually kill. If a fungus started to develop a "cancer", then too bad for the fungus, but since cancer isn't contagious, there's really nothing that need concern you.
Perhaps some chemicals cause tumours in both human and fungus, but the danger is from the original chemical only, not the resulting cancerous growth on the fungus. Indeed, should you find such a growth, keep it and send it to a lab. They would be very interested in determining if the mechanism involved has a medical application.

Answer 2

No, in-fact certain mushrooms are being tested for use in combatting cancer such as the Mitake mushroom (especially the 'D-Fraction' version) due to their beta glucans which have been shown in lab tests to attack tumors and they also increase the immune system response (NK killer cells, etc.). It all depends on the mushroom, however, and Mitake is being given more attention nowadays because it can be taken effectively orally.

Answer 3

There is no scientific basis to link fungus and cancer-but if it bothers you that much, don't eat mushrooms. Also avoid vinegar or anything pickled, soy sauce. beer, wine and cheese, since all these items are produced by utilizing natural fungi.
A bit more problematic might be avoiding breathing, since air can contain billions of fungi and their spores.
Good luck.

Answer 4

They are fungus but cancer does not "grow" anywhere. There are many factors that cause cancer such as enviroment, genetics, certain viruses, etc.