Prevalence, incidence, and natural history of simple ovarian cysts among women >55 years old in a large cancer screening trial.

<bold>Objective: </bold>The purpose of this study was to measure the occurrence and natural history of simple ovarian cysts in a cohort of older women.<bold>Study Design: </bold>Simple cysts were ascertained among a cohort of 15,735 women from the intervention arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial through 4 years of transvaginal ultrasound screening.<bold>Results: </bold>Simple cysts were seen in 14% of women the first time that their ovaries were visualized. The 1-year incidence of new simple cysts was 8%. Among ovaries with 1 simple cyst at the first screen, 54% retained 1 simple cyst, and 32% had no cyst 1 year later. Simple cysts did not increase risk of subsequent invasive ovarian cancer.<bold>Conclusion: </bold>Simple ovarian cysts are fairly common among postmenopausal women, and most cysts appear stable or resolve by the next annual examination. These findings support recent recommendations to follow unilocular simple cysts in postmenopausal women without intervention. [ABSTRACT FROM AUTHOR]