Denmark-wide cohort study of association between body mass index and colorectal cancer recurrence and mortality

A nationwide cohort study in Denmark investigated the association of body mass index (BMI) wit colorectal cancer (CRC) recurrence and mortality. The cohort included 33,926 patients with a stage I-III CRC diagnosis between 2002 and 2020. The median duration of follow-up was 4.4 years (IQR 1.7-4.6) for recurrence and 4.5 years (2.7-4.6) for mortality. At diagnosis, 3% of patients had underweight, 43% normal weight, 37% overweight, 13% obesity, and 4% class II-III obesity. Overall, 5877 patients (18.4%) experienced CRC recurrence and 6568 (21.8%) died within 5 years from diagnosis. BMI was not associated with recurrence. Underweight and class II-III obesity were associated with increased mortality, especially for rectal cancer. For rectal cancer, class II-III obesity was associated with excess mortality, particularly in younger patients (aged 30-50 years) and males. Type 2 diabetes had minor influence on the associations. The authors conclude that targeted interventions considering the high-risk subgroups may help improve CRC outcomes (visual abstract).