Investigating the performance and costeffectiveness of the simple ultrasound-based rules compared to the risk of malignancy index in the diagnosis of ovarian cancer (SUBSONiC-study): Protocol of a prospective multicenter cohort study in the Netherlands

Estimating the risk of malignancy is essential in the management of adnexal masses. An accurate differential diagnosis between benign and malignant masses will reduce morbidity and costs due to unnecessary operations, and will improve referral to a gynecologic oncologist for specialized cancer care, which improves outcome and overall survival.