There is an element of truth in it. It is better to avoid unnecessary X-rays, to exercise and to eat a healthy diet that favors fruits and vegetables. I don't know that that will prevent breast cancer, but it will improve your health and quality of life in many other ways.
As to the rest, it's wishful thinking, and even worse, yet another way of blaming the victim. I've seen at least two of my patients who treated their breast cancer with diet and herbs, and avoided any other medical treatment die. Horrible, ugly, completely preventable deaths. If they'd come in for treatment the moment they found a lump instead of dicking around with crystals and a macrobiotic diet, they'd likely be still walking around spreading their noxious gospel of positive thinking.
And FYI, numerous studies have shown that a "positive attitude" doesn't do squat to improve the odds of beating cancer. It may improve the quality of the remaining time, but it doesn't cure anything. I'm all in favor of allowing patients to explore other options in treating disease, but not if it means rejecting the best evidence-based medical practice. And not if it means making dying people think that the reason they're in such terrible shape is because they did something wrong.
What you're advocating isn't just silly. It's downright dangerous.
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