Thinking logically can be exhausting.....

[Colanth]

And relieving stress and relaxing can help get rid of minor illnesses just because your body is running at it's best capabilities. But cancer? Replacement for chemotherapy? I don't think so. Maybe if they mean that it will relieve some of the ailments that go along with treatment / cancer?

Replacement for chemo, of course not.  But it's been shown that if you're calm and relaxed through the treatment (was it Norman Mailer who credited Groucho Marx's movies for his cancer cure?), you have a better chance of survival.  Whether that's due to the actual effect of "alternative medicine" or the placebo effect is irrelevant.