ECO 2026
Timing, pace of weight gain shape cancer risk
Clinical Takeaway: Tracking weight over time, not just at a single visit, may better flag patients who could benefit from prevention discussions. Early adult obesity carried especially heavy risk, suggesting opportunities for cancer-focused conversations decades before most screening starts.
One BMI reading is the standard input for most obesity-related risk assessments, but it can miss the steepness and timing of weight gain that may matter most to cancer risk. This study followed weight from age 17 through 60 in a Swedish pooled cohort of more than 630,000 adults to see how life-course trajectories shape cancer incidence at specific sites. Findings come from a conference abstract and preprint and have not yet been peer reviewed.
Comparing the top with the bottom quintile of weight change from ages 17 to 60, risk of established obesity-related cancers was 46% higher in men and 43% higher in women. Site-specific signals were larger: liver cancer risk was 2.67 times higher in men, esophageal adenocarcinoma 2.25 times higher, and endometrial cancer 3.78 times higher in women. Pituitary tumors, an emerging signal in obesity-cancer research, were 3.13 times higher in men and 2.13 times higher in women.
Weight at age 17 was independently associated with several cancers, often with effects similar to later weight gain. Men who became obese before age 30 had five times the risk of liver cancer and roughly double the risk of pancreatic and renal cell cancers. Women with obesity before 30 had a 4.5-fold higher risk of endometrial cancer and a 76% higher risk of meningioma.
In women, weight gain after age 30 was most strongly tied to endometrial cancer, postmenopausal breast cancer, and meningioma. In men, weight gain before age 45 drove most of the link with esophageal and liver cancer.
The analysis pooled data from the Obesity and Disease Development Sweden study, with 251,041 men and 378,981 women followed through 2023 and a median of four weight measurements per person between ages 17 and 60.
"Both early adult body weight and weight gain across adulthood were associated with the risk of most established and some potentially obesity-related cancers, with differences by cancer site, sex, and timing of weight gain," said lead author Anton Nilsson, PhD, associate professor in the Department of Translational Medicine at Lund University.
Source: Nilsson A. medRxiv (preprint). 2026 Apr 24. Weight Trajectories and Cancer Risk: A Pooled Cohort Study. Presented at the European Congress on Obesity 2026