OBJECTIVE - The objective of the study was to estimate the age-specific incidence of endometrial hyperplasia: simple, complex, and atypical, in order of increasing likelihood of progression to carcinoma.
STUDY DESIGN - Women aged 18-90 years with endometrial pathology specimens (1985-2003) at a large integrated health plan were identified using automated data. Incidence rates were obtained by dividing the number of cases by the estimated number of female health plan enrollees who retained a uterus.
RESULTS - Endometrial hyperplasia peak incidence was: simple, 142 per 100,000 woman-years, complex, 213 per 100,000 woman-years, both in the early 50s; and atypical, 56 per 100,000 woman-years in the early 60s. Age-adjusted incidence decreased over the study period, especially for atypical hyperplasia.
CONCLUSION - Endometrial hyperplasia incidence without and with atypia peaks in the early postmenopausal years and in the early 60s, respectively. Given that some cases of endometrial hyperplasia likely go undiagnosed, the figures provided should be viewed as minimum estimates of the true incidence.