This review concluded that PET–CT (positron emission tomography-computed tomography) might supplement surveillance techniques, particularly for patients with an increasing CA 125 (cancer antigen 125) level and negative CT or MR imaging. The interpretation of the data appeared reasonable, but presence of publication bias, low study quality and variation across studies suggested the findings should be interpreted with caution.

To compare the diagnostic performance of CA 125 (cancer antigen 125), PET (positron emission tomography) alone, PET-CT (positron emission tomography-computed tomography), CT and MRI (magnetic resonance imaging) for diagnosing recurrent ovarian carcinoma on a per-patient and per-lesion basis.

MEDLINE, EMBASE, CANCERLIT, The Cochrane Library, Chinese Biomedical Literature Database and China National Knowledge Infrastructure were searched for English-language or Chinese-language studies from 1995 to November 2007; search terms were reported. Reference lists of included articles were searched for additional studies.

Studies of 10 or more patients in which CA 125, PET (whether interpreted with or without the use of CT), CT or MRI were used to detect recurrent ovarian carcinoma were eligible for inclusion. The reference standard was histopathologic analysis and/or close clinical and imaging follow-up for at least six months. For per-patient or per-lesion estimates, sufficient data were required to calculate true-positive and false-negative values. If the same data were presented in more than one article then the most detailed or most recent was selected. Excluded studies were CT studies without contrast agent and those that used sequential test combinations. Where stated, the mean age of patients in included studies ranged from 42 to 67 years of age (age range 17 to 90 years of age).

Four reviewers independently selected studies for inclusion (each reviewer selected studies from their own field); these were checked by another reviewer and disagreements were resolved by consensus.

Study quality was assessed using QUADAS (Quality Assessment of Diagnostic Accuracy Studies Assessment) criteria.

The authors did not state how many reviewers performed the quality assessment.

Data required to calculate sensitivity and specificity (numbers of true positives, false negatives, false positives and true negatives) on a per-patient or per-lesion basis were extracted using a standardised form.

Four reviewers independently performed the data extraction. Disagreements were resolved through consultation with a fifth reviewer and the majority opinion used.

Pooled estimates of sensitivity and specificity, with corresponding 95% confidence intervals (CIs), were calculated using a random-effects model. Heterogeneity was assessed using the Χ² and I² tests. The Spearman correlation was used to identify a possible threshold effect (cut-off effect was considered present where ρ>0.4). Weighted summary receiver operating characteristic (sROC) curves were presented and the area under the curve (AUC) calculated. Publication bias was assessed through funnel plots.

A total of 34 studies (n=1,895) met the inclusion criteria. Blinding was undertaken in 13 studies; 21 studies were either not blinded or blinding status was not defined. In 15 studies the reference standard was histopathologic analysis. Eleven studies showed verification bias.

CA was evaluated in 15 studies, PET alone in 11 studies, PET-CT in 11 studies, CT in 10 studies and MRI in five studies.

Specificity for CA 125 was 0.93 (95% CI 0.89 to 0.95), PET alone was 0.89 (95% CI 0.83 to 0.94), PET–CT was 0.88 (95% CI 0.81 to 0.93), CT was 0.84 (95% CI 0.76 to 0.90) and MRI was 0.78 (95% CI 0.70 to 0.85).

Sensitivity for PET–CT was 0.91 (95% CI 0.88 to 0.94), PET alone was 0.88 (95% CI 0.84 to 0.92), CT was 0.79 (95% CI 0.74 to 0.84), MRI was 0.75 (95% CI 0.69 to 0.80) and CA 125 was 0.69 (95% CI 0.65 to 0.72).

The area under the curve of CA 125 was 0.9219, PET alone was 0.9297, PET–CT was 0.9555, CT was 0.8845 and MRI was 0.7955.

Results of pairwise comparison between each modality demonstrated area under the curve of PET, whether interpreted with or without the use of CT, was higher than that of CT or MR, p<0.05. The pooled sensitivity, pooled specificity and AUC showed no statistically significant difference between PET alone and PET–CT.

Based on Spearman correlation coefficients there was no evidence for a cut-off effect for any modalities. There was heterogeneity among studies and evidence of publication bias.

PET–CT might be a useful supplement to current surveillance techniques, particularly for those patients with an increasing CA 125 level and negative CT or MR imaging. However, regarding to diagnostic accuracy, interpreted CT images may have limited additional value on PET in detecting recurrent ovarian cancer.

The review addressed a clearly stated research question, defined by appropriate inclusion criteria. Searches of several sources were restricted to studies published in English or Chinese and there was no apparent search for unpublished studies; relevant data may, therefore, have been omitted from the review and language bias may have been present. Publication bias was assessed and found likely to be present. Appropriate methods were taken to minimise error and bias for study selection and data extraction, but it was unclear whether this applied to validity assessment. Study quality was assessed using appropriate criteria, although the authors did not report an overall score or comment upon study quality; from the details provided the quality of the included studies was fairly poor. Details of the studies and results were detailed clearly in tables. Heterogeneity was assessed and found to be present. The authors' interpretation of the data presented appeared reasonable, but these data may not represent the entire evidence base, publication bias was present, study quality appeared low and there was significant variation across studies; these findings should, therefore, be interpreted with caution.

Practice: The authors stated that PET–CT might be a useful supplement to current surveillance techniques, particularly for those patients with an increasing CA 125 level and negative CT or MR imaging.

Research: The authors stated that there was a need for high-quality prospective studies to compare MR and CT for detecting recurrent ovarian cancers and to address the heterogeneity detected between studies.

Not stated.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.