Life Course Trajectories of Body Mass Index and Risk of Cancer in Adulthood: Systematic Review and Meta-Analysis.

[OBJECTIVE] This systematic review and meta-analysis aimed to identify common life-course body mass index (BMI) trajectories (childhood/adulthood to adulthood) and their impact on risk of cancer overall and cancer at different sites in adulthood.

[METHODS] Observational studies were identified that assessed the association of BMI trajectories with cancer risks from databases published in English. The pooled effect sizes were estimated using a random-effects model.

[FINDINGS] A total of 24 eligible studies were included in the meta-analysis. Transitioning from normal weight to obesity was significantly associated with an increased risk of colorectal cancer (effect size [ES] = 1.170, 95% CI: 1.096, 1.245), pancreatic cancer (ES = 1.337, 95% CI: 1.247, 1.426), kidney cancer (ES = 2.122, 95% CI: 1.619, 2.624), and liver cancer (ES = 1.777, 95% CI: 1.261, 2.293), compared to those in the stable normal weight trajectory. No significant difference in the risk of breast or prostate cancer was observed when comparing various BMI trajectories to a stable normal BMI trajectory.

[CONCLUSION] The findings suggest that lifetime BMI trajectories influence cancer risk, with a transition from normal BMI to higher levels associated with an increased risk of cancer. The impact varied by trajectory and cancer type. Further studies are needed to confirm these findings.