Cancer cases under 50 rose globally in Europe, US, and Asia. Millennials born 80s-90s hit hardest by early-onset cancers. US saw sharpest rises in colorectal, pancreatic, and stomach cancers 2010-2019. Gen X and millennials have higher risk for many cancer types than prior generations. Genetics plays a role but lifestyle and environment drive the surge. Alcohol classified as top carcinogen fueling colorectal and breast cancers in youth. Diet changes and inactivity blamed for gastrointestinal cancer boom. Early screening like colonoscopy recommended before age 45. Maintaining healthy weight slashes cancer risk. Cutting alcohol and boosting exercise prevents most cases. Independent studies confirm the young adult cancer epidemic.