Recent studies have shown that
cancer risk related to
overweight and
obesity is mediated by time and might be better approximated by using life years lived with excess weight. In this study we aimed to assess the impact of
overweight duration and intensity in older adults on the risk of developing different forms of
cancer. Study participants from seven European and one US cohort study with two or more weight assessments during follow-up were included (n = 329,576). Trajectories of body mass index (BMI) across ages were estimated using a quadratic growth model;
overweight duration (BMI ≥ 25) and cumulative weighted
overweight years were calculated. In multivariate Cox models and random effects analyses, a longer duration of
overweight was significantly associated with the incidence of
obesity-related
cancer [overall hazard ratio (HR) per 10-year increment: 1.36; 95 % CI 1.12-1.60], but also increased the risk of postmenopausal breast and
colorectal cancer. Additionally accounting for the degree of
overweight further increased the risk of
obesity-related
cancer. Risks associated with a longer
overweight duration were higher in men than in women and were attenuated by smoking. For postmenopausal
breast cancer, increased risks were confined to women who never used
hormone therapy. Overall, 8.4 % of all
obesity-related
cancers could be attributed to
overweight at any age. These findings provide further insights into the role of
overweight duration in the etiology of
cancer and indicate that weight control is relevant at all ages. This knowledge is vital for the development of effective and targeted
cancer prevention strategies.