Lifestyle risk factors for serrated colorectal polyps: a systematic review and meta-analysis

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Aims

Certain categories within the classification of colorectal serrated polyps (SP) are now understood to carry malignant potential. The aim of this systematic review was to investigate the association between modifiable lifestyle factors and SP risk.

Methods

A search was conducted systematically within Medline, Embase and Web of Science, for relevant literature published by June 2015. Adjusted relative risks (RR) and 95% confidence intervals (CI) were combined using random effects meta-analyses to assess the risk of SP, where possible.

Results

Forty-four papers were identified, analysing SP risk and seven different lifestyle factors: smoking, alcohol, body fatness, diet, physical activity, medication and/or hormone replacement therapy (HRT) use. When comparing the highest and lowest categories of exposure, significant elevated risks of SP were identified for tobacco smoking (RR 2.54, 95% CI 2.18-2.97); alcohol intake (RR 1.38, 95% CI 1.23-1.55), body mass index (RR 1.35, 95% CI 1.18-1.53), and high fat and meat intakes. Direct associations for smoking and alcohol, but not body fatness, tended to be stronger for sessile serrated adenomas/polyps than hyperplastic polyps. Contrastingly, significant decreased SP risks were observed for non-steroidal anti-inflammatory drug and aspirin users (RR 0.78, 95% CI 0.69- 0.88), and high folate, calcium and fiber intakes. No significant associations

Conclusion

Several lifestyle factors, most notably smoking and alcohol, are associated with SP risk, subgroups of which have recently been implicated in carcinogenesis. These findings enhance our understanding of potential mechanisms involved, and suggest that serrated pathway colorectal neoplasms could be prevented via changes in lifestyle.