Risk of uterine, ovarian and breast cancer following pelvic inflammatory disease: A nationwide population-based retrospective cohort study

Background: Pelvic inflammatory disease (PID) is characterized by infection and inflammation of the upper genital tract in women and is associated with health sequelae. We used a nationwide population-based retrospective cohort study to explore the relationship between PID and the subsequent development of gynecological cancers including ovarian, breast or uterine cancer. Methods: We identified subjects diagnosed with PID between January 1^st, 2000 and December 31^st, 2002 in the Taiwan National Health Insurance Research Database. A comparison cohort constructed for patients without PID were matched according to age and sex. All PID patients and control groups were observed until diagnosed with ovarian, breast or uterine cancer, or until death, withdrawal from the NHI system, or until December 31^st, 2009. Results: The PID cohort consisted of 32,268 patients, and an equal number of matched controls without PID. The adjusted hazard ratio (HR) of ovarian, breast or uterine cancer in subjects with PID were: HR 1.326 (95 % confidence interval: 0.775-2.269), HR: 1.039 (95 % confidence interval: 0.862-1.252), and HR: 1.439 (95 % confidence interval: 0.853-2.426) respectively in comparison with controls during follow-up. Conclusions: This large nationwide population-based cohort study suggests that there is no increased risk for ovarian, breast or uterine cancer among women who have PID compared to a matching population.