External validation of diagnostic models to estimate the risk of malignancy in adnexal masses

Diagnosis, treatment, and follow-up of borderline ovarian tumors

Borderline ovarian tumors represent a heterogeneous group of noninvasive tumors of uncertain malignant potential with characteristic histology. They occur in younger women, are present at an early stage, and have a favorable prognosis, but symptomatic recurrence and death may be found as long as 20 years after therapy in some patients. The molecular changes in borderline ovarian tumors indicate linkage of this disease to type I ovarian tumors (low-grade ovarian carcinomas). The pathological stage of disease and subclassification of extraovarian disease into invasive and noninvasive implants, together with the presence of postoperative macroscopic residual disease, appear to be the major predictor of recurrence and survival. However, it should be emphasized that the most important negative prognostic factor for recurrence is just the use of conservative surgery, but without any impact on patient survival because most recurrent diseases are of the borderline type-easily curable and with an excellent prognosis. Borderline tumors are difficult masses to correctly preoperatively diagnose using imaging methods because their macroscopic features may overlap with invasive and benign ovarian tumors. Over the past several decades, surgical therapy has shifted from a radical approach to more conservative treatment; however, oncologic safety must always be balanced. Follow-up is essential using routine ultrasound imaging, with special attention paid to the remaining ovary in conservatively treated patients. Current literature on this topic leads to a number of controversies that will be discussed thoroughly in this article, with the aim to provide recommendations for the clinical management of these patients.

Ultrasound criteria and CA 125 as predictive variables of ovarian cancer in women with adnexal tumors

OBJECTIVES

To evaluate the capacity to predict malignancy in women with adnexal tumors using CA 125 measurement and ultrasound criteria.

METHODS

This was a cross-sectional study including 103 women with a total of 110 adnexal tumors. CA 125 level was measured in a sample of peripheral blood. Lesions were classified by ultrasound, using standardized predetermined criteria, as benign (B) or malignant (M). Those that could not be classified by these criteria were assessed subjectively. Histopathologic examination of surgical specimens was used as the gold standard.

RESULTS

Of 110 tumors, 79 (71.8%) were benign and 31 (28.2%) were malignant on histopathology. Ultrasound criteria could be applied to 91 (82.7%) tumors, resulting in a sensitivity of 90%, specificity of 87%, positive predictive value (PPV) of 69% and negative predictive value (NPV) of 97%. In tumors not classifiable according to ultrasound criteria, subjective sonographic assessment gave a sensitivity of 67%, specificity of 80%, PPV of 75% and NPV of 73%. At a cut-off point of 37.4 U/mL, CA 125 had a sensitivity of 69%, a specificity of 87.8%, a PPV of 69% and a NPV of 88% for detection of malignancy. When CA 125 was associated with age and ultrasound criteria in a logistic regression model, the sensitivity and specificity increased in the subset of sonographically malignant tumors.

CONCLUSION

The majority of tumors were correctly classified using ultrasound criteria. CA 125 alone performed worse than did ultrasound in discriminating malignant from benign adnexal tumors. CA 125 measurement contributed to the diagnosis of malignancy, improving overall specificity, only in sonographically malignant tumors.

Key findings from the International Ovarian Tumor Analysis (IOTA) study: an approach to the optimal ultrasound based characterisation of adnexal pathology

The principal aim of the IOTA project has been to develop approaches to the evaluation of adnexal pathology using ultrasound that can be transferred to all examiners. Creating models that use simple, easily reproducible ultrasound characteristics is one approach.

Discrimination ability of prediction models for ordinal outcomes: relationships between existing measures and a new measure

In this paper, we focus on measures to evaluate discrimination of prediction models for ordinal outcomes. We review existing extensions of the dichotomous c-index-which is equivalent to the area under the receiver operating characteristic (ROC) curve--suggest a new measure, and study their relationships. The volume under the ROC surface (VUS) scores sets of cases including one case from each outcome category. VUS considers sets as either correctly or incorrectly ordered by the model. All other existing measures assess pairs of cases. We propose an ordinal c-index (ORC) that is set-based but, contrary to VUS, scores sets more gradually by indicating the closeness of the model-based ordering to the perfect ordering. As a result, the ORC does not decrease rapidly as the number of outcome categories increases. It turns out that the ORC can be rewritten as the average of pairwise c-indexes. Hence, the ORC has both a set- and pair-based interpretation. There are several relationships between the existing measures, leading to only two types of existing measures: a prevalence-weighted average of pairwise c-indexes and the VUS. Our suggested measure ORC positions itself in between as it is set-based but turns out to equal an unweighted average of pairwise c-indexes. The measures are demonstrated through a case study on the prediction of six-month outcome after traumatic brain injury. In conclusion, the set-based nature and graded scoring system make the ORC an attractive measure with a simple interpretation, together with its prevalence-independence that is a natural property of a discrimination measure.

Triaging women with ovarian masses for surgery: observational diagnostic study to compare RCOG guidelines with an International Ovarian Tumour Analysis (IOTA) group protocol

OBJECTIVE

To compare guidelines from the Royal College of Obstetricians and Gynaecologists (RCOG) based on the Risk of Malignancy Index (RMI) with a protocol based on logistic regression model LR2 developed by the International Ovarian Tumour Analysis (IOTA) group for triaging women with an ovarian mass as low, moderate, or high risk of malignancy.

DESIGN AND SETTING

Observational diagnostic study conducted between 2005 and 2007 at 21 oncology referral centres, referral centres for ultrasonography and general hospitals.

SAMPLE

In all, 1938 women undergoing surgery for an ovarian mass.

METHODS

RCOG guidelines use the RMI to triage women as low (RMI < 25), moderate (25-250), or high (above >250) risk. The IOTA protocol uses LR2s estimated probability of malignancy (<0.05 indicates low risk, ≥ 0.05 but <0.25 moderate risk, and ≥ 0.25 high risk).

MAIN OUTCOME MEASURE

Percentages of benign, borderline and invasive tumours classified as low, moderate or high risk.

RESULTS

The IOTA and RCOG protocols classified 71.1% and 62.1% of benign tumours as low risk, respectively (difference 9.0; 95% CI 6.2-11.9, P < 0.0001). Of invasive tumours, 88.6% and 73.6% were labelled high risk (difference 15.0; 10.6-19.4, P < 0.0001), and 3.0% and 5.2% were labelled low risk (difference -2.2; -4.6 to 0.2, P = 0.07) respectively by each protocol. Similar results were found after stratification for menopausal status.

CONCLUSIONS

The IOTA protocol was more accurate for triage than the RCOG protocol. The IOTA protocol would avoid major surgery for more women with benign tumours while still appropriately referring more women with an invasive tumour to a gynaecological oncologist.

Multianalyte assay systems in the differential diagnosis of ovarian cancer

INTRODUCTION

The efficient triage of women diagnosed with a pelvic mass presents a current area of unmet need. Unnecessary surgical intervention performed on patients at a decreased risk of malignancy represents a significant source of preventable morbidity, anxiety and cost. Likewise, delayed or overlooked referral of patients harboring malignant tumors is strongly associated with diminished outcomes. Current tools including imaging modalities and the CA 125 blood test are of insufficient accuracy to overcome these challenges. The use of multianalyte assays systems which include additional biomarkers capable of complementing the performance of CA 125 may offer the best hope of improvement.

AREAS COVERED

Recent findings regarding the use of multianalyte biomarker panels for the differential diagnosis of a pelvic mass are reviewed and discussed. Particular attention is paid to to the FDA approved ROMA and OVA1 tests. The development, validation, recent evaluation and comparative performances of these two tests are reviewed in detail.

EXPERT OPINION

The performances achieved by the ROMA and OVA1 diagnostic tests represent significant milestones in the application of multianalyte assay systems into standard clinical practice. The overall impact and cost-effectiveness of widespread clinical use of these tools remains to be evaluated.