Abstract

Background

Insulin-like growth factor-I (IGF-I) plays a role in cancer development, and circulating concentrations of IGF-I have been found to be associated with increased risk of several cancers. However, the relationship between IGF-I and bladder cancer is still unknown, and has yet to be investigated in a large-scale prospective study. The aim of this study was to investigate the association between pre-diagnostic plasma IGF-I and risk of overall bladder cancer in a case-control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.

Method

A total of 843 men and women diagnosed with bladder cancer between 1992 and 2005 were matched with 843 controls by recruitment centre, sex, age at recruitment, date at recruitment, duration of follow-up, time of day and fasting status at blood collection using an incidence density protocol. Plasma IGF-I concentrations were measured using the IDS-iSYS immunoassay system. Odds ratios (ORs) and 95% confidence intervals were calculated using conditional logistic regression with adjustment for smoking status.

Results

No association was found between IGF-I concentration and overall bladder cancer risk (adjusted OR for highest versus lowest fourth: 0.91, 95% CI: 0.66-1.24, P-trend=0.40). There was no significant evidence of heterogeneity in the association with IGF-I by tumour aggressiveness (P-heterogeneity > 0.05).

Conclusion

In this first prospective study, there was no evidence of an association between plasma IGF-I concentrations and bladder cancer risk.