RELATIONSHIP BETWEEN HISTORY OF GESTATIONAL DIABETES AND THE RISK OF BREAST CANCER: A POPULATION BASED COHORT STUDY

Background: Although a positive association between type 2 diabetes and breast cancer has been reported, an association with gestational diabetes mellitus (GDM) is less clear. This study aimed to assess the relationship between the history of GDM and the incidence of BC a long term population based study. Methods: To conduct this research, 4076 women aged 20-50 years who participated in the first phase of Tehran-Lipid-and-Glucose-Study, who had at-least one pregnancy were included. Each participants were asked about the history of GDM every 3 years. They was evaluated about the occurrence of breast cancer (BC). Cox-survival analysis was used to measure the Hazard-ratio (HR) for both groups with and without history of GDM Results: The study population included 886 women with prior GDM and 3,909 women without history of GDM. The median duration of follow-up among women with and without the history of GDM were 12.12 and 11.62 years, respectively. The incidence of BC was 0.64 per 1,000 year-olds with confidence=interval of 95% (0.44-0.91). Among them, 4 cases were reported in women with GDM and 26 cases in women without GDM. (Incidence of 0.36 per 1000 person-years with confidence=interval 95% (0.11-0.99) in women with prior GDM and 0.73 per 1,000 person-years with confidence=interval 95% (0.49-1.1) in women without a history of GDM. Conclusion: Our study showed that the history of GDM is not an independent risk factor for breast cancer.