Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. Individuals with an overweight or obese body mass index (BMI) are at increased risk for developing colorectal cancer and non-colorectal gastrointestinal cancers.

Evidence Rating Level: 2 (Good)

Colorectal cancer (CRC) is the 5th most common cancer diagnosed in the United States. Though screening programs have improved the early detection and treatment of CRC, it remains an important public health concern. Obesity rates are rising globally, and obesity is a known risk factor for developing GI cancers. This retrospective cohort study used data from the Prostate, Lung, Colorectal, and Ovarian (PCLO) Cancer Screening Trial to investigate the association between BMI and the risk of developing CRC and non-colorectal GI cancers. The PCLO trial included participants aged 55 to 74, enrolled between November 8, 1993, and July 2, 2001. Analysis of the trial data initially occurred after 13 years of follow-up or December 2009, whichever came first, with the option to opt-in for further follow-up until December 2014. There were 135,161 participants included in the study population. 34,946 of these individuals were diagnosed with cancer during the trial, of which 5088 were GI cancers, including 2803 colorectal, 376 esophageal, 485 gastric, 348 liver, and 1076 pancreatic. Researchers determined that there was an increased risk of colorectal cancer for individuals with overweight BMI (HR, 1.23; 95% CI, 1.10-1.37) in early adulthood, overweight (HR, 1.23; 95% CI, 1.13-1.34) and obese (HR, 1.55; 95% CI, 1.38-1.75) BMI in middle adulthood, and overweight (HR, 1.21; 95% CI, 1.10-1.32) and obese (HR, 1.39; 95% CI, 1.25-1.54) BMI in later adulthood. They also found an increased risk of non-colorectal GI cancer associated with obese BMI (HR, 1.37; 95% CI, 1.04-1.80) in early adulthood, overweight (HR, 1.13; 95% CI, 1.03-1.24) and obese (HR, 1.44; 95% CI, 1.27-1.65) BMI in middle adulthood, and overweight (HR, 1.13; 95% CI, 1.03-1.24) and obese (HR, 1.36; 95% CI, 1.21-1.53) BMI in later adulthood. The researchers postulate that this relationship may be related to the state of chronic inflammation associated with increased BMI. Future research may assess whether weight loss is effective for reducing the risk of developing GI cancers for those with overweight or obese BMI at different stages of life.

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