Is inguinal hernia associated with an increased risk of colon cancer? A systematic review and meta-analysis

The presence of an inguinal hernia has been associated with an increased risk of identifying colon cancer, and therefore colonoscopy is recommended prior to inguinal hernia repair. However, the evidence on the association between the presence of an inguinal hernia and colon cancer is conflicting and uncertain. We performed a systematic review and meta-analysis to synthesize all available evidence on this topic.

A comprehensive search of PubMed and EMBASE was performed. Any comparative study (case-control or cohort study) comparing the rate of colon cancer detection in patients with and without inguinal hernias who underwent screening colonoscopy or flexible sigmoidoscopy was eligible for inclusion. Data were extracted and pooled under a random effects model.

The initial search identified 692 references, of which 4 comparative studies (1462 patients) met the inclusion criteria. The overall risk of bias in the included studies was low. Pooled results showed a statistically non-significant difference in the incidence of detection of colon cancer, with patients with inguinal hernia having a 1.26 times increased likelihood of colon cancer diagnosis compared with patients without inguinal hernia (odds ratio (OR) 1.26; 95% confidence interval (CI) 0.63-2.51; P = 0.51). Although patients with inguinal hernia were also 1.23 times more likely to be diagnosed with colon polyps compared to patients without inguinal hernia, this difference was statistically non-significant (OR 1.23; 95% CI 0.94-1.60; P = 0.12).

The findings from this first systematic review and meta-analysis show that there is no difference in the incidence of either colon cancer or colon polyps in patients presenting with inguinal hernias compared to those without. Nevertheless, larger prospective studies are needed to further investigate the relationship between the risk of colon cancer or polyps and the presence of inguinal hernia.