The immune system does attack cancerous cells daily. A good example would be a mole and how it stops growing. Otherwise it would continue to expand indefinitely.

Some people have taken Reishi mushroom at super high doses to super charge killer t cells*immune related), some have had success in wiping out lung cancer. Doctors baffled as usual...

Also lack of circulation can play a role in diseased states

The immune system does attack cancerous cells daily. Also lack of circulation can play a role in diseased states