1. The original Simple Rules (2008)

The Simple Rules are a preoperative classification system for ovarian tumors, consisting of five features typical for benign tumors (B-features) and five features typical for malignant tumors (M-features), see Figure 1. The Simple Rules can be used to diagnose ovarian cancer in women who have at least one persistent adnexal (ovarian, para-ovarian, and tubal) tumor and are considered to require surgery. Based on which of the B- and M-features that apply, tumors are classified as Benign, Malignant or Inconclusive:

  • Benign - Only B-features apply
  • Malignant - Only M-features apply
  • Inconclusive - no features apply, or both B- and M-features apply

Figure 1. The 10 features from the Simple Rules

The Simple Rules were developed by clinicians and statisticians from the International Ovarian Tumor Analysis (IOTA) group, based on clinical and ultrasound data from 1066 women recruited at 9 centers in 5 countries (Italy, Belgium, Sweden, France, and UK). All patients included required surgery as judged by a local clinician. All current diagnostic models for adnexal tumors (e.g. IOTA models, RMI, ROMA) have been created for patients undergoing surgery, i.e. patients selected for expectant management were excluded when creating the model.

The manuscript describing the Simple Rules is published in Ultrasound in Obstetrics and Gynecology (Timmerman et al, 2008).1The Simple Rules have been successfully validated in several studies.2-13

The Simple Rules cannot replace training and experience in ultrasonography and cannot compensate for poor quality ultrasound equipment. The parameters used in the Simple Rules are based on the terms and definitions as published by the IOTA group.14

The original SR is implemented electronically in various formats:

By installing this software you agree to the terms of the License Agreement.

2. The Simple Rules risk (SRrisk) calculation (2016)

The Simple Rules have the important drawback that they do not give a predicted risk, and hence not a level of confidence in the classification. This was overcome by the development of the SRrisk calculation tool15. This is based on a logistic regression model with the ten features and the type of center (oncology center vs other) as predictors. Oncology centers were defined as tertiary referral centers with a specific gynecological oncology unit.

The model was developed by clinicians and statisticians from the International Ovarian Tumor Analysis (IOTA) group, and is based on clinical and ultrasound data from almost 6000 women recruited at 24 center in 10 countries (Italy, Belgium, Sweden, Czech Republic, Poland, France, UK, China, Spain, and Canada). All patients included required surgery as judged by a local clinician. All current diagnostic models for adnexal tumors (e.g. IOTA models, RMI, ROMA) have been created for patients undergoing surgery, i.e. patients selected for expectant management were excluded when creating the model. As a consequence the Simple Rules risk calculation cannot be applied to conservatively treated adnexal tumors.

The manuscript describing the SRrisk model is published in American Journal of Obstetrics and Gynecology (Timmerman, Van Calster, et al, 2016).15

The Simple Rules risk calculation cannot replace training and experience in ultrasonography and cannot compensate for poor quality ultrasound equipment. The parameters used in the Simple Rules risk calculation are based on the terms and definitions as published by the IOTA group.14

References

  1. Timmerman D, et al. Ultrasound Obstet Gynecol 2008;31:681-90.
  2. Timmerman D, et al. BMJ 2010;341:c6839.
  3. Testa AC, Kaijser J, et al. Br J Cancer 2014;111:680-8.
  4. Fathallah K, et al. Gynecol Obstet Fertil 2011;39:477-81.
  5. Hartman CA, et al. Ultrasound Obstet Gynecol 2012;40:360-6.
  6. Alcázar JL, et al. Ultrasound Obstet Gynecol 2013;42:467-71.
  7. Sayasneh A, et al. Br J Cancer 2013;108:2448-54.
  8. Tantipalakorn C, et al. Asian Pac J Cancer Prev 2014;15:5123-6.
  9. Nunes N, et al. Ultrasound Obstet Gynecol 2014;44:503-14.
  10. Tinnangwattana D, et al. Asian Pac J Cancer Prev 2015;16:3835-8.
  11. Ruiz de Gauna B, et al. Eur J Obstet Gynecol Reprod Biol 2015;191:10-4.
  12. Knafel A, et al. Ultraschall Med 2015 Jun 30. [Epub ahead of print].
  13. Alcázar JL, et al. Ultrasound Obstet Gynecol 2016;48:397-402.
  14. Timmerman D, et al. Ultrasound Obstet Gynecol 2000;16:500-505.
  15. Timmerman D, Van Calster B, et al. Am J Obstet Gynecol 2016;214:424-437.