Association between Echinococcus granulosus infection and cancer risk - a pilot study in Cyprus.
BACKGROUND
Infections from microorganisms and parasites have been connected with either increased or decreased cancer risk. The objective of this study was to investigate whether infection by Echinococcus granulosus is associated with cancer risk.


METHODS
We assembled a pilot retrospective cohort of patients who were diagnosed as being infected by E. granulosus in Cyprus between 1930 and 2011. Age/gender-matched non-infected family members and neighbors were selected as references. Medical history was ascertained from each study subject through in-person interview. Cox proportional hazards regression analysis was performed to assess the association of being infected by E. granulosus with cancer risk.


RESULTS
Individuals with prior infection by E. granulosus (n=249) were more likely to have cancer compared to those without infection (n=753), 11.65% vs. 8.37% (p=0.0492). Survival analysis also showed that subjects with prior infection had a higher risk for developing cancer. The hazards ratio (HR) was 1.595, [95% confidence interval (CI) between 1.008 and 2.525]. The risk ratio did not change significantly (HR=1.536; 95% CI: 0.965-2.445) after adjusting for gender, year of birth, smoking status, alcohol consumption, and family history of cancer.


CONCLUSIONS
Our study suggests that infection by E. granulosus may increase cancer risk. If this observation can be confirmed independently, further investigation of the mechanisms underlying the association is warranted.
Katerina
K
Oikonomopoulou
Herbert
H
Yu
Zhanwei
Z
Wang
Stella K
SK
Vasiliou
Davor
D
Brinc
Georgios
G
Christofi
Marilena
M
Theodorou
Pavlos
P
Pavlou
Andreas
A
Hadjisavvas
Christiana A
CA
Demetriou
Kyriacos
K
Kyriacou
Eleftherios P
EP
Diamandis
D000368:Aged; D000818:Animals; D015331:Cohort Studies; D003535:Cyprus; D004443:Echinococcosis / Q000150:complications* / Q000469:parasitology; D005260:Female; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000150:complications* / Q000469:parasitology*; D010865:Pilot Projects; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors