As a physician, I have encountered many people who believe that heart disease, which is the single biggest cause of death among Americans, is largely controllable. After all, if people ate better, were physically active and stopped smoking, then lots of them would get better. This ignores the fact that people can't change many risk factors of heart disease like age, race and family genetics. People don't often seem to feel the same way about cancer. They think it's out of their control. A ... recent study published in Nature argues that there is a lot we can do. Many studies have shown that environmental risk factors and exposures contribute greatly to many cancers. Diet is related to colorectal cancer. Alcohol and tobacco are related to esophageal cancer. HPV is related to cervical cancer, and hepatitis C is related to liver cancer. And you'd have to be living under a rock not to know that smoking causes lung cancer and that too much sun can lead to skin cancer. Using sophisticated modeling techniques, the researchers argued that less than 30 percent of the lifetime risk of getting many common cancers was because of intrinsic risk factors, or the "bad luck." The rest were things you can change. [More] recently, in JAMA Oncology, researchers sought to quantify how a healthful lifestyle might actually alter the risk of cancer. They [found that] about 25 percent of cancer in women and 33 percent in men was potentially preventable.