Association between adult weight gain and colorectal cancer: a dose-response meta-analysis of observational studies.
This study investigated the association between adult weight gain and risk of colorectal cancer (CRC). Using terms related to weight gain and CRC, we searched PubMed, Embase and Web of Science for relevant studies published before June 2014. Two evaluators independently selected studies according to the selection criteria, and eight studies were included (three case-control and five cohort studies). Summary estimates were obtained using fixed- or random-effects models. The relative risk (RR) of the association between adult weight gain and CRC was 1.25 (95% confidence interval [CI], 1.10-1.43); the RR was 1.30 (95% CI, 1.14-1.49) for colon cancer (CC) and 1.27 (95% CI, 1.02-1.58) for rectal cancer (RC) for the highest versus lowest category. For every 5-kg increase in adult weight, the risk increased by 5% (RR, 1.05; 95% CI, 1.02-1.09) for CRC, 6% (RR, 1.06; 95% CI, 1.02-1.11) for CC and 6% (RR, 1.06; 95% CI, 1.03-1.08) for RC. The subgroup analyses showed a positive association between adult weight gain and risk of CRC only in men, and the RR was 1.65 (95% CI, 1.42-1.92) for the highest versus lowest category of adult weight gain and 1.10 (95% CI, 1.06-1.15) for a 5-kg increase in adult weight. In conclusion, there is evidence that adult weight gain is associated with an increased risk of CRC. However, the positive association between adult weight gain and risk of CRC is stronger among men than among women.