Changes in pre-diagnostic serum C-reactive protein concentrations and ovarian cancer risk: a longitudinal study

Background: Evidence suggests that inflammation may be associated with increased risk of ovarian cancer but there is paucity of studies investigating this association, especially using over-time changes in inflammatory biomarkers. Materials and methods: We conducted a prospective population-based case-control study nested within the Finnish Maternity Cohort (FMC). Within the FMC, 170 women with ovarian cancer who had donated serum samples to the cohort twice, >= 1 year apart, before cancer diagnoses were identified. One control per case was matched for age, parity and sampling date. Results: Comparing the highest with lowest tertiles, the odds ratio (OR) of ovarian cancer using the first set of serum samples (mean lag time to cancer diagnosis 9.0 years) was 1.62 [95% confidence interval (CI) 0.93-2.83]. However, analysis conducted using the second set of serum samples donated closer to cancer diagnosis (mean lag time 6.4 years) revealed a significantly increased risk of ovarian cancer comparing extreme tertiles of C-reactive protein (CRP) concentrations; OR 1.96 (95% CI 1.11-3.4). Over time, increases in individuals' CRP concentrations were also associated with increased risk; OR 1.90 (95% CI 1.12-3.23). Conclusion: The results suggest that inflammation may precede ovarian cancer since increasing CRP concentrations, both across tertiles and longitudinally at the individual level, were associated with increased risk.