Researchers link weight gain to higher cancer risk

Researchers at Lund University said on May 13 that adults who gained the most weight across adulthood faced higher risks of several obesity-related cancers, according to findings presented at the European Congress on Obesity in Istanbul. The analysis used Swedish cohort data covering weight records from 1911 to 2020 and cancer follow-up through 2023. The researchers said the pattern held for men and women, with the sharpest increases seen in several site-specific cancers. The results were presented at ECO 2026, a medical meeting that ran from May 12 to May 15. ### How large was the study behind the new findings? The Swedish ODDS study included 251,041 men and 378,981 women, with each participant contributing an average of four weight measurements between ages 17 and 60, the conference release said. The researchers then linked those records to cancer outcomes through 2023. Anton Nilsson and Tanja Stocks, both at Lund University’s Department of Translational Medicine, were listed as the study’s lead researchers. (e3.eurekalert.org) The release said most earlier studies had focused on body weight at a single point in time or on change between only two time points, rather than weight trajectories across adult life. ### What did the researchers find when they compared the biggest gainers with the smallest? (e3.eurekalert.org) The top 20% of adult weight gain was linked to a 7% higher risk of all cancers combined in men and a 17% higher risk in women, compared with the lowest 20%, according to the ECO release. For established obesity-related cancers, the increase was 46% in men and 43% in women. (e3.eurekalert.org) Specific cancers showed larger jumps. Men in the highest weight-gain group had a 2.67-fold higher risk of liver cancer and a 2.25-fold higher risk of oesophageal cancer, while women had a 3.78-fold higher risk of endometrial cancer, the release said. Smaller increases were also reported for gastric cardia and rectal cancer in men, postmenopausal breast cancer and meningioma in women, and colon cancer and renal cell carcinoma in both sexes. (e3.eurekalert.org) ### Which cancers count as obesity-related in the broader evidence base? The National Cancer Institute says overweight and obesity are linked to an increased risk of 13 types of cancer. Those include cancers of the breast after menopause, colon and rectum, endometrium, esophagus, kidney, liver, ovary, pancreas, stomach cardia, thyroid, gallbladder and meningioma, as well as multiple myeloma. (e3.eurekalert.org) The U.S. Centers for Disease Control and Prevention says excess weight can lead to long-lasting inflammation and higher-than-normal levels of insulin, insulin-like growth factor and sex hormones. The agency says cancer risk rises with the more excess weight a person gains and the longer a person is overweight. ### How does this fit into the wider U.S. health burden? (cancer.gov) The U.S. Department of Agriculture’s National Institute of Food and Agriculture says diet-related illnesses, including cardiovascular disease, type 2 diabetes and certain cancers, are a leading source of poor health in the United States. The agency says those illnesses also weigh on healthcare spending, worker productivity, military readiness and health disparities. (cdc.gov) The American Cancer Society said its 2026 annual report provides updated estimates of new cancer cases, deaths, survivors and prevention statistics for the United States. That report does not itself measure the Lund study’s findings, but it places the new results in a country where cancer burden remains large and closely tracked by public health agencies. (nifa.usda.gov) ### What should readers keep in mind about these results? The May 13 findings were presented at a scientific congress, not in a peer-reviewed journal paper cited in the conference release. Conference findings can change as researchers complete peer review, add analyses or revise methods. ECO 2026 ended on May 15 in Istanbul, and the Lund University researchers were identified in the conference materials as the named authors to watch for any subsequent paper or updated presentation materials. (cancer.org) (e3.eurekalert.org)