What is the most accurate whole-body imaging modality for assessment of local and distant recurrent disease in colorectal cancer? A meta-analysis : imaging for recurrent colorectal cancer

Abstract

Purpose: The objective of this study was to compare the diagnostic performance of positron emission tomography (PET), PET/CT, CT and MRI as whole-body imaging modalities for the detection of local and/or distant recurrent disease in colorectal cancer (CRC) patients who have a (high) suspicion of recurrent disease, based on clinical findings or rise in carcinoembryonic antigen (CEA).

Methods: A meta-analysis was undertaken. PubMed and Embase were searched for studies on the accuracy of whole-body imaging for patients with suspected local and/or distant recurrence of their CRC. Additionally, studies had to have included at least 20 patients with CRC and 2 × 2 contingency tables had to be provided or derivable. Articles evaluating only local recurrence or liver metastasis were excluded. Summary receiver-operating characteristic (ROC) curves were constructed from the data on sensitivity and specificity of individual studies and pooled estimates of diagnostic odds ratios (DORs) and areas under the ROC curve (AUCs) were calculated. To test for heterogeneity the Cochran Q test was used.

Results: Fourteen observational studies were included which evaluated PET, PET/CT, CT and/or MRI. Study results were available in 12 studies for PET, in 5 studies for CT, in 5 studies for PET/CT and in 1 study for MRI. AUCs for PET, PET/CT and CT were 0.94 (0.90-0.97), 0.94 (0.87-0.98) and 0.83 (0.72-0.90), respectively. In patient based analyses PET/CT had a higher diagnostic performance than PET with an AUC of 0.95 (0.89-0.97) for PET/CT vs 0.92 (0.86-0.96) for PET.

Conclusion: Both whole-body PET and PET/CT are very accurate for the detection of local and/or distant recurrent disease in CRC patients with a (high) suspicion of recurrent disease. CT has the lowest diagnostic performance. This difference is probably mainly due to the lower accuracy of CT for detection of extrahepatic metastases (including local recurrence). For clinical practice PET/CT might be the modality of choice when evaluating patients with a (high) suspicion of recurrent disease, because of its best performance in patient based analyses and confident prediction of disease status.

Fig. 1

PRISMA flowchart describing the identification and inclusion of studies

Fig. 2

SROC curves with all individual study results for all modalities. The single study on MRI is displayed as a single value in the graph. PET (n = 12), CT (n = 5), PET/CT (n = 5), MRI (n = 1)

Fig. 3

Pooled sensitivity (%) and specificity (%), area under the ROC curve (AUC, %) and diagnostic odds ratio (DOR) for CT, PET and PET/CT with 95% confidence intervals indicated by error bars

Fig. 4

Areas under the SROC curve with 95% confidence intervals (error bars) per modality for subgroups. Prevalence refers to the prevalence of disease in the studied population. Fully blinded is defined as reading the images without any knowledge about the patient. Clinical info indicates that readers were aware of clinical information about the patients, but had no knowledge about results from other imaging studies. In some subgroups columns are missing for one or more modalities, because no or only one study was available for that subgroup and thus the subgroup analysis could not be performed

Fig. 5

Diagnostic CT image (left) and PET image (right) of a patient who has a clearly visualised para-aortic lesion on PET (arrow), which cannot be discerned on CT

Fig. 6

CT image (left) and PET image (right) of a patient with locally recurrent colorectal cancer after a sigmoid resection. On PET a clear hot spot (arrow) is found with increased FDG uptake, while on CT it was not recognised as a local recurrence (arrow)