Regular physical exercise has not been clinically proven to reduce the chances of having a later diagnosis of cancer. yes or no?

Exercise is good: It is difficult to do a controlled trial for such an issue. However, there is plenty of evidence that exercise is good for health, e.g., it prolongs life, prevents diabetes and heart disease, it likely protects against cancer by avoiding weight gain, better balance prevents falls and fractures. Though not applicable to you exercise prevents breast cancer. See this site: http://www.cancer.gov/cancertopics/pdq/prevention/breast/Patient/page3