GO02 : Markedly increased risk of malignancies for females with endometriosis: A nationwide population-based cohort study

Objective: Endometriosis is correlated with various cancers. However, the risk of cancer has not been established in a nationwide, population-based cohort of patients newly diagnosed with endometriosis. Methods: A retrospective population-based cohort study was performed using claims database of the Korean National Health Insurance from January 2008 to December 2018. Patients diagnosed with endometriosis between 2010 and 2013 were included; those who underwent appendectomy but were not diagnosed with endometriosis during the study period served as controls. None of these participants had been diagnosed with cancer prior to enrollment. ICD-10 cancer diagnoses were compared between these groups. Results: A total of 179,865 patients with endometriosis and 87,408 controls were analyzed, and the incidence rates of cancer were 644.3 and 543.8 per 100,000 person-years, respectively. Compared with controls, patients with endometriosis had a significantly increased overall risk of cancer (hazard ratio [HR], 1.34; 95% confidence interval [CI], 1.281.40; P < 0.001) after adjustment for age, insurance type, and comorbidities. They showed significantly increased risk of uterine (HR, 4.59; 95% CI, 3.565.91; P < 0.001), ovarian (HR, 2.51; 95% CI, 1.993.16; P < 0.001), cervical (HR, 1.84; 95% CI, 1.492.28; P < 0.001), breast (HR, 1.44; 95% CI, 1.311.58; P < 0.001), and thyroid (HR, 1.34; 95% CI, 1.241.45; P < 0.001) cancers. The median age at diagnosis was <50 years for all cancer types. Conclusion: Endometriosis was correlated with an increased risk of cancer, specifically uterine, ovarian, cervical, breast, and thyroid cancers. Patients with endometriosis should begin cancer screening early.