title: Investigating the performance and cost-effectiveness 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.
abstract: BACKGROUND
  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. The Risk of Malignancy Index is currently the most commonly used method in clinical practice, but has a relatively low diagnostic accuracy (sensitivity 75-80% and specificity 85-90%). Recent reports show that other methods, such as simple ultrasound-based rules, subjective assessment and (Diffusion Weighted) Magnetic Resonance Imaging might be superior to the RMI in the pre-operative differentiation of adnexal masses.
  
  
  METHODS
  A prospective multicenter cohort study will be performed in the south of The Netherlands. A total of 270 women diagnosed with at least one pelvic mass that is suspected to be of ovarian origin who will undergo surgery, will be enrolled. We will apply the Risk of Malignancy Index with a cut-off value of 200 and a two-step triage test consisting of simple ultrasound-based rules supplemented -if necessary- with either subjective assessment by an expert sonographer or Magnetic Resonance Imaging with diffusion weighted sequences, to characterize the adnexal masses. The histological diagnosis will be the reference standard. Diagnostic performances will be expressed as sensitivity, specificity, positive and negative predictive values and likelihood ratios.
  
  
  CONCLUSIONS
  We hypothesize that this two-step triage test, including the simple ultrasound-based rules, will have better diagnostic accuracy than the Risk of Malignancy Index and therefore will improve the management of women with adnexal masses. Furthermore, we expect this two-step test to be more cost-effective. If the hypothesis is confirmed, the results of this study could have major effects on current guidelines and implementation of the triage test in daily clinical practice could be a possibility.
  
  
  BACKGROUND
  ClinicalTrials.gov: registration number NCT02218502.
authors.affiliation: Department of Obstetrics and Gynecology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. evelyne.meys@mumc.nl.|GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. evelyne.meys@mumc.nl.
authors.forename: Evelyne M J
authors.initials: EM
authors.lastname: Meys
authors.affiliation: Department of Obstetrics and Gynecology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. iris.rutten@mumc.nl.|GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. iris.rutten@mumc.nl.
authors.forename: Iris J G
authors.initials: IJ
authors.lastname: Rutten
authors.affiliation: Department of Obstetrics and Gynecology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. r.kruitwagen@mumc.nl.|GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. r.kruitwagen@mumc.nl.
authors.forename: Roy F P M
authors.initials: RF
authors.lastname: Kruitwagen
authors.affiliation: Department of Obstetrics and Gynecology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. brigitte.slangen@mumc.nl.|GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. brigitte.slangen@mumc.nl.
authors.forename: Brigitte F
authors.initials: BF
authors.lastname: Slangen
authors.affiliation: Department of Obstetrics and Gynecology, Laurentius Ziekenhuis Roermond, Mgr. Driessenstraat 6, PO Box 920, , 6040 AX, Roermond, The Netherlands. m.bergmans2@lzr.nl.
authors.forename: Martin G M
authors.initials: MG
authors.lastname: Bergmans
authors.affiliation: Department of Obstetrics and Gynecology, Orbis Medical Centre Sittard, Dr. H. van der Hoffplein 1, PO Box 5500, , 6130 MB, Sittard, The Netherlands. h.mertens@orbisconcern.nl.
authors.forename: Helen J M M
authors.initials: HJ
authors.lastname: Mertens
authors.affiliation: Department of Obstetrics and Gynecology, St. Jans Gasthuis Weert, Vogelsbleek 5, PO Box 29, , 6000 AA, Weert, The Netherlands. e.nolting@sjgweert.nl.
authors.forename: Ernst
authors.initials: E
authors.lastname: Nolting
authors.affiliation: Department of Obstetrics and Gynecology, VieCuri Venlo, Tegelseweg 210, PO Box 1926, , 5900 BX, Venlo, The Netherlands. dboskamp@viecuri.nl.
authors.forename: Dieuwke
authors.initials: D
authors.lastname: Boskamp
authors.affiliation: GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. r.beets.tan@mumc.nl.|Department of Radiology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. r.beets.tan@mumc.nl.
authors.forename: Regina G H
authors.initials: RG
authors.lastname: Beets-Tan
authors.affiliation: Department of Obstetrics and Gynecology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. toon.van.gorp@mumc.nl.|GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre (MUMC+), P. Debyelaan 25, 6202 AZ, Maastricht, The Netherlands. toon.van.gorp@mumc.nl.
authors.forename: Toon
authors.initials: T
authors.lastname: van Gorp
mesh_terms: D000328:Adult; D003362:Cost-Benefit Analysis; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D009426:Netherlands; D010051:Ovarian Neoplasms / Q000000981:diagnostic imaging / Q000191:economics / Q000473:pathology; D011446:Prospective Studies; D012107:Research Design; D012306:Risk; D014463:Ultrasonography; D055815:Young Adult