Does exercise really help prevent cancer or is that not true ?

Exercise and cancer: Good question. In large scale observational studies those who exercise seem to have less cancer. But there has never been a proper trial in which say 100,000 folks were randomized to exercise or not and then a long term follow up showed less cancer in those who exercised. Probably will never be such a trial as too expensive. We do know that stopping smoking reduces risk as does regular colonsocpy