Association of overweight, obesity, and recent weight loss with colorectal cancer risk

Overweight and obesity, conditions with rising prevalence in many countries, are associated with increased colorectal cancer (CRC) risk. However, many patients with CRC lose weight before diagnosis, which may lead to underestimation of the association. A population-based case-control study of 11,887 participants in Germany found an inverse association between overweight and CRC risk when body mass index (BMI) at the time of recruitment was considered. However, recent weight loss was associated with strongly increased CRC risk, and a clear positive association between BMI and CRC risk emerged when looking at earlier points in time, which was particularly pronounced for BMI 8 or more years before diagnosis/interview. The authors conclude that prediagnostisc weight loss bias can lead to a considerable underestimation of the association of BMI with CRC.