A large scale population-based cohort study on the risk of ovarian neoplasm in patients with type 2 diabetes mellitus

Abstract

Objective: To investigate whether the risk of developing ovarian cancer is elevated in women with diabetes mellitus.

Methods: The study is a population-based cohort study. Women with type 2 diabetes (n=319,310) and age-matched controls (n=319,308) were selected from the ambulatory care claims and beneficiary registry in 2000, respectively. Selected patients were linked to the in-patient claims (2000-2008) to identify admissions due to ovarian (ICD-9-CM: 183.xx) cancer. The person-year approach with Poisson assumption was used to estimate the incidence density rate. The age-specific hazard ratios (HRs) of ovarian cancer in relation to diabetes were calculated using multivariate Cox proportional hazard regression model.

Results: The overall incidence density rate of ovarian cancer was estimated at 1.87 (95% confidence interval (CI) 1.70-2.05) per 10,000 patient-years for patients with diabetes. The corresponding figures for controls were slightly lower at 1.79 per 10,000 patient-years. The incidence density of ovarian cancer was increased with age in diabetes but not in controls. The covariate-adjusted HR for ovarian cancer was statistically compared with null (adjusted HR=1.06, 95% CI=0.92-1.22) in women with diabetes. Moderately elevated HR was noted in women with diabetes aged <50 (adjusted HR=1.17, 95% CI=0.82-1.65) and in women with diabetes aged >65 (adjusted HR=1.10, 95% CI=0.92-1.42). The null association between diabetes and ovarian cancer remains true regardless of the disease duration of diabetes.

Conclusion: This large-scale cohort study provides little support on the putative association between type 2 diabetes and the risk of ovarian cancer.

Keywords: Cohort studies; Cox model; Diabetes; Incidence rate; Ovarian cancer; Relative risk.