RESUMEN
Classifying endometrial hyperplasia (EH) according to the severity of glandular crowding (simple hyperplasia (SH) vs complex hyperplasia (CH)) and nuclear atypia (simple atypical hyperplasia (SAH) vs complex atypical hyperplasia (CAH)) should predict subsequent endometrial carcinoma risk, but data on progression are lacking. Our nested case-control study of EH progression included 138 cases, who were diagnosed with EH and then with carcinoma (1970-2003) at least 1 year (median, 6.5 years) later, and 241 controls, who were individually matched on age, date, and follow-up duration and counter-matched on EH classification. After centralised pathology panel and medical record review, we generated rate ratios (RRs) and 95% confidence intervals (CIs), adjusted for treatment and repeat biopsies. With disordered proliferative endometrium (DPEM) as the referent, AH significantly increased carcinoma risk (RR=14, 95% CI, 5-38). Risk was highest 1-5 years after AH (RR=48, 95% CI, 8-294), but remained elevated 5 or more years after AH (RR=3.5, 95% CI, 1.0-9.6). Progression risks for SH (RR=2.0, 95% CI, 0.9-4.5) and CH (RR=2.8, 95% CI, 1.0-7.9) were substantially lower and only slightly higher than the progression risk for DPEM. The higher progression risks for AH could foster management guidelines based on markedly different progression risks for atypical vs non-atypical EH.