Rising obesity rates may be fueling a global surge in several cancers — and every generation is feeling the impact.Researchers analyzed cancer trends from 42 countries between 2003 and 2017 – focusing on 13 types that have been climbing among younger adults -- ages 20 to 49.They found incidence rates for thyroid, breast, colon, kidney, endometrial cancer and leukemia rose sharply in younger adults in the majority of countries but surprisingly they also increased among older adults – with one exception.Colon cancer increased far more steeply in people under 50, possibly due to exposure to novel carcinogens and better screening among older adults, according to the researchers.They say every cancer type that rose in both younger and older groups has been linked to obesity and the resulting metabolic changes.Meanwhile, liver, oral, esophageal, and stomach cancers declined among younger adults in most countries.The authors say these findings underscore the urgent need for stronger prevention efforts targeting obesity and lifestyle risks — at every age.Source: Annals of Internal MedicineAuthor Affiliations: The Institute of Cancer Research, Imperial College London, National Cancer Institute .Sign up for our weekly HealthDay newsletter