The idea behind Perfect Health is that you can positively affect your level of health, immune system, and recovery from illness when you direct your mind and body to good health and well-being. Your mind is an amazing and powerful ally to your overall health. Your friend might also consider Spring Forest Qigong for health, a form of visualization, exercise, and meditation. Although I have not heard from anyone with cancer about their results while using Perfect Health, perhaps someone on the forum has an experience to share. I also suggest checking out the Spring Forest Qigong forum where you can do a search on cancer.
Our best to you and your friend!