Lifestyle modification can prevent almost half of all cancers, says Leslie Kohman, MD, left, the Upstate Cancer Center's associate director for community outreach. In this interview, she goes over the things people can do -- or avoid -- to help prevent cancer. The first is not to use tobacco, followed closely by maintaining a healthy weight. Kohman discusses diet, sun protection, immunizations and environmental factors and explains the difference between early detection of cancer and the ability for some screenings to catch cancers before they even develop.