The first time my wife had cancer, we were using the AOS-1MP from www.appliedozone.com We just turned it on and left it on in the bedroom while we slept. We would take it downstairs and put it in the living area and leave it on a lot of the day. It doesn't use an oxygen tank, but worked.
The second time my wife got cancer we had bought the "beta" model from www.plasmafire.com We mostly just breath the residual ozone from making water each night for 2-4 hours. We drink at least 2 glasses of water a day. When she had cancer she would drink up to about a 1/2 gallon a day. Most of the time it was just 2 glasses though.
I forgot to mention ozone works good on joint pains also. I had a really screwed up neck and started funneling it and I'm amazed at how much of the pain is gone. My wife also had a bad back and got a depo-medrol shot. (don't ever get one! they use the same thing that's in anti-freeze, and inject it in or near your spinal cord. makes sense.) After that she had burning pains in the feet. After just 1 funneling session the burning was gone. It really helpd the pain in her back too. I think like most alternative treatments, it's really a lifestyle change. You have to keep doing it the rest of your life.