Risk of endometrial cancer in women with pelvic inflammatory disease: a nationwide population-based retrospective cohort study
Teng-Kai Yang 1, Shiu-Dong Chung2, Chih-Hsin Muo3, Chao-Hsiang Chang4 Chao-Yuan Huang5, Chi-Jung Chung6
1Surgery department, Yonghe Cardinal Hospital, New Taipei city, Taiwan;
2Division of Urology Department of Surgery, Far Eastern Memorial Hospital, New Taipei, Taiwan;
3Department of Public Health, China Medical University, Taichung, Taiwan;
4Department of Urology, China Medical University and Hospital, Taichung, Taiwan;
5Department of Urology, National Taiwan University Hospital, Taipei, Taiwan;
6Department of Health Risk Management, College of Public Health, China Medical University, Taichung, Taiwan;
Endometrial cancer (EC) is fatal with rising incidence and mortality. Pelvic inflammatory disease (PID), a common gynecologic disease, had been connected to EC, but the evidence was scarce. We aimed to investigate the association between PID and EC.
Materials and Methods:
We constituted a nationwide population-based cohort study and data were obtained from the National Health Insurance Research Database (NHIRD). We defined 41065 patients with PID as the PID group, and 82130 randomly selected patients as the comparison group through frequency matching by age and index year. Diagnosis of related diseases was conducted according to the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). Each patient was individually tracked to identify those who developed EC. Cox proportional hazards regression and the Kaplan-Meier method were used in the analysis.
Overall, the incidence rate of 9.6 and 16.1 per 100000 person-year and mean follow-up duration of 4.84 and 6.63 years were observed among patients in the PID and non-PID cohorts, respectively. After adjusting for potential risk factors, PID women were observed to have a 1.78-fold higher risk of developing endometrial cancer compared with the non-PID cohort. Consideration for other potential risk factors, the incidence of EC increased with ageing, particular for those aged over 50 years (HR = 2.44, 95% CI = 1.28-4.63). In addition, for women with hypertension, the increased EC risk was also shown in PID patients compared to non-PID cohort.
In the large-scale population-based study, we indicated the increased EC risk in PID patients, particular for patients with older age or those with hypertension. Future, large-scale clinical trial would be required to clarify the role of medication played in PID-related EC progress.