I've never heard anyone saying yoga can cure cancer. I have heard them saying it can improve your core stability and balance and strength, which can help prevent back injuries and posture-induced problems and reduce the risk of falls and resulting injuries. It can help with stress. There are some excellent yoga teachers around. There are others who are quite bonkers, but they may suit other people who aren't me.
I do like a regular massage, too, but I know others who hate it. When I've been on yoga retreats and I don't have to do all the cooking, I tend to eat at more healthily, too, though there's already a lot of vegetables in my diet.
It's known that obesity can make some cancers more likely, and if someone finds juicing helps them lose weight and consume more veg, that's not a bad thing (though if they contain lots of tropical fruit, then they can be too sugary.) If people are fitter through doing yoga or swimming or gym classes, that is no bad thing, either.
I like the Kur system in Germany. My German boyfriend spent time there after he had a stroke, and I stayed for a week (we paid for my bit.) He was there with someone preparing for a hip op (physiotherapy to build strength before), and people recovering from accidents, operations and illnesses. One of my German colleagues, his wife is currently in for about 5 weeks, to manage her depression better. As a visitor, I enjoyed salt water swimming pools open air heated pools, beautiful grounds and a healthy canteen. But countries like Germany pay out a lot more for health care, as we should. They have a big Wellness industry, but it looked effective me, with a focus on prevention, with a lot more pre- and post-care. I don't know how much different levels of health insurance can affect what you get.
But there is also a lot of woo around, and my father getting terminal cancer diagnosis brought them out of the woodwork. It's fed by people wanting to do whatever they can to keep hold of the people they love, but it can give false hope and cost money - for all those who are well-meaning but deluded, there are also those who are just scammers.