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

- Investigations on the risk of ovarian cancer in type 2 diabetes are inconclusive due to certain methodological concerns.
- A recent meta-analysis suggested a 17% increase in risk of ovarian cancer in type 2 diabetes.
- This large study provides little support for the association of type 2 diabetes with risk of ovarian cancer.

ObjectiveTo investigate whether the risk of developing ovarian cancer is elevated in women with diabetes mellitus.MethodsThe 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.ResultsThe 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.ConclusionThis large-scale cohort study provides little support on the putative association between type 2 diabetes and the risk of ovarian cancer.