Human papillomavirus infection and colorectal cancer risk: a meta-analysis

Aim Human papillomavirus (HPV) infection is associated with cervical cancer, but whether it is involved in colorectal carcinogenesis is controversial. We conducted a meta-analysis to evaluate the association between HPV and colorectal adenocarcinoma. Method A search of the MEDLINE database was performed using the MESH terms 'HPV', 'human papillomavirus', and 'colon cancer', 'rectal cancer', 'colorectal cancer'. The prevalence of HPV infection in colorectal cancer was estimated by pooling data from 16 studies (involving 1436 patients) published up to July 2012, taking into consideration methodological heterogeneity between studies. The association of HPV with colorectal cancer risk was estimated from case-control studies. Results The HPV overall prevalence was 31.9% (95% CI: 19.3-47.9). It was lowest in Europe (14.1%, 95% CI: 4.9-34.1) and highest in South America (60.8%, 95% CI: 42.7-76.4). Eight studies presented the results of HPV typing in 302 HPV-positive colorectal carcinomas. HPV 18 was the virus more frequently found in colorectal cancer cases from Asia (73.34%, 95% CI: 44.9-90.7) and Europe (47.3%, 95% CI: 34.5-60.4). In contrast, HPV 16 was more prevalent in colorectal tumours from South America (58.3%, 95% CI: 45.5-69.9). The analysis of five case-control studies showed an increase in colorectal carcinoma risk with HPV positivity (OR = 10.04; 95% CI: 3.7-27.5). Conclusion The results provide quantitative evidence for an association between HPV infection and colorectal cancer risk.