Background and study aims: Obesity is a risk factor for colorectal neoplasia. Lifestyle modifications, including weight loss, have been advocated to reduce the risk. However, no prospective study has evaluated whether weight loss actually affects adenoma recurrence. The aim of this study was to examine whether weight change (loss or gain) over 4 years is associated with adenoma recurrence. Patients and methods: A total of 1826 patients with colorectal adenoma in the Polyp Prevention Trial had their height and weight measured at baseline. Adenoma recurrence was determined by end of trial colonoscopy 4 years after study entry when patients' weights were re-measured. Poisson regression models were used to evaluate body mass index (BMI), weight change over 4 years, and the risk of any adenoma and advanced adenoma recurrence. Results: Adenoma recurrence was observed in 723 patients (39.6 %), 118 (6.5 %) of whom had advanced adenoma recurrence. Among those with baseline BMI < 25 kg/m (n = 466), BMI 25 - 29 kg/m (n = 868), and BMI 30 kg/m (n = 492), the recurrence rate was 34.5 %, 41.0 %, and 41.9 %, respectively. Obesity was associated with an increased risk of adenoma recurrence (RR = 1.19; 95 %CI 1.01 - 1.39) and advanced adenoma recurrence (RR = 1.62; 95 %CI 1.01 - 2.57). However, when compared with those with relatively stable weight (weight change < 5 lb) over the 4-year trial, weight gain or loss was not associated with adenoma recurrence. This was consistent, regardless of the baseline BMI. Conclusions: Weight loss or gain over 4 years does not affect adenoma recurrence. This study does not support weight loss alone as an effective intervention for reducing adenoma recurrence.
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