Effects of human papillomavirus infection on prevalence of colorectal cancer: a systematic review and meta-analysis of global data

Background
Several studies have emerged in the past two decades investigating the role of human papillomavirus infection in colorectal cancer development. To better inform global prevention strategies for colorectal cancer, we reviewed available evidence on the associations between human papillomavirus infection and colorectal cancer.
Methods
In this systematic review and meta-analysis, we searched PubMed, Embase, Cochrane Library, Web of Science, and websites of international conferences for studies published before Dec 31, 2019. Interventional or observational studies containing original quantitative data describing associations between human papillomavirus and incidence or prevalence of colorectal cancer were included. We calculated pooled odds ratios (ORs) and their 95% CIs using random-effect models. We assessed risk of bias using the Newcastle-Ottawa scale.
Findings
We identified 20 observational studies including 1424 cases of colorectal cancer or adenoma and 1363 controls. The prevalence of human papillomavirus was 34·5% in the group with colorectal cancer or adenoma and 17% in the control group. Human papillomavirus was associated with a three-fold increase in colorectal cancer overall (OR 3·05, 95% CI 2·01–4·62; heterogeneity I2 63·5%). In the subgroup analysis, human papillomavirus was associated with increased colorectal cancer prevalence in controls (2·96, 1·16–7·61; I2 75·3%) and in the group with adjacent normal tissues (3·05, 2·12–4·40; I2 31·2%).
Interpretation
We found evidence that human papillomavirus is likely to be associated with increased colorectal cancer prevalence. Prevention of human papillomavirus infection could be considered for inclusion in campaigns promoting prevention strategies for colorectal cancer.