Effects of Endometriosis and Pelvic Inflammatory Disease on Endometrial Cancer and Uterine Sarcoma Development: A Critical Time Window from a Population-Based Cohort Study in Taiwan

Abstract

Background: The effects of endometriosis and pelvic inflammatory disease (PID) on endometrial cancer and uterine sarcoma development have not yet been compared; moreover, the impact of disease duration on the significantly increased risk of uterine cancer risk warrants investigation. Methods: This population–based cohort study compared uterine cancer risk in 135236 age-matched comparison females, 114726 with PID and 20510 with endometriosis, of 982495 female individuals in Taiwan. Multiple Cox regression was used to adjust the demographic characteristics and comorbidities, conditional Cox regression after propensity score matching (PSM) to deal with the potential confounding, and the landmark analysis to assess the time varying effect. Findings: Uterine cancer risk increased by 194% (95% CI 116–300) in the endometriosis group. The adjusted hazard ratios (aHRs) increased after classifying uterine cancer into endometrial cancer (aHR 2·92 [95% CI 2·12–4·03]) and uterine sarcoma (aHR 5·83 [2·02–16·89]). Moreover, the aHR of uterine cancer in the endometriosis group increased in the PSM cohort (aHR 2·83 [CI 1·70–4·71]). The highest uterine cancer risk was noted in patients from 37 to 60 months after diagnosis and in younger individuals (12 to 35 years) in the endometriosis group. Interpretation: Endometriosis demonstrated a pronounced effect on the development of not only uterine carcinoma but also sarcoma than PID did. The highest uterine cancer risk was noted in female individuals after 3 to 5 years diagnosis. Endometriosis is a crucial factor for developing uterine cancer early in young females. Funding: This study was supported by grants (grant numbers: CSH-2019-C-002 and CSH-2019-C-005) from the Chung Shan Medical University Hospital without interest conflicts. Declaration of Interests: None. Ethics Approval Statement: Approval from Chung Shan Medical University Hospital Institutional Review Board (CSMUH No: CS17129) and informed consent waived.