Is there a risk of cancer development after Campylobacter infection?

Objective. All Campylobacter jejuni species produce a genotoxin, which induce DNA double strand breaks, could lead to an increased risk of cancer especially in the gastro-intestinal tract. Material and methods. All individuals in Stockholm County who tested positive with C. jejuni between 1989 and 2006 were included. The cohort was followed-up until December 31, 2007 for the occurrence of cancer, overall and site specific. Standard incidence ratios (SIR) with 95% confidence intervals (CI) were calculated by comparisons with the background population. Results. There were 16,276 individuals who tested positive for C. jejuni generating 124,387 person years. Excluding the first year of follow-up the overall risk for cancer did neither differ from that expected SIR = 0.95 (95% CI 0.82-1.09) nor after 10 years or more of follow-up; SIR = 0.91 (95% CI 0.71-1.16). There was no increased risk for cancer in the gastro-intestinal tract, but there were significantly increased risks for melanomas SIR = 1.84 (95% CI 1.27-2.57) and squamous cell skin cancer SIR = 1.52 (95% CI 1.01-2.19) while a significantly decreased risk of respiratory cancers among males SIR = 0.32 (95% CI 0.12-0.70) was observed. Conclusions. Our results indicate no excess risks of malignancies following an infection by C. jejuni at least during the first decade. Furthermore, the finding of a decreased risk of respiratory cancers could be of interest, if the results are reproduced in future studies in other populations.