Staging of patients with colorectal cancer often requires a multimodality, multistep imaging approach.
Colonography using a combined modality of positron emission tomography and computed tomography provides whole-body tumor staging in a single session.
Dr Patrick Veit-Haibach and colleagues from Germany determined the staging accuracy of the combined whole-body colonography methods.
The research team compared these with the staging accuracies of computed tomography followed by positron emission tomography and computed tomography alone.
The team evaluated the effect of combined colonography on therapy planning.
The researchers compared the results with conventional computed tomography staging of the abdomen and thorax and optical colonoscopy.
|74% of lesions were correctly staged with combined colonography|
|Journal of the American Medical Association|
The researchers conducted a prospective study of 47 patients with a mean age of 71 years, enrolled between 2004 and 2006.
The patients had clinical findings and optical colonoscopy that suggested primary colorectal cancer.
Patients underwent whole-body combined colonography 1 day after colonoscopy.
The study was conducted at a university hospital with a mean follow-up of 447 days.
The main outcome was correct classification of Tumor Node Metastases stage using combined colonography vs computed tomography alone or followed by positron emission tomography.
Secondary outcome measures were the accurate assessment of Tumor-, Node-, and Metastases-stage by combined colonography.
These results were compared with computed tomography alone or followed by positron emission tomography.
The researchers also considered the effects of combined colonography on therapy planning.
The team identified a total of 50 lesions in the patients.
The researchers noted that the overall Tumor Node Metastases stage was correctly determined in 74% of lesions with combined colonography.
Computed tomography correctly identified 52% of lesions with a 0.7-cm node threshold.
Combined colonography was more accurate in defining Tumor Node Metastases stage vs abdominal computed tomography staging alone.
The researchers based the difference in accuracy mainly on a more accurate definition of the T-stage.
The team did not detect differences in defining N-stage between combined colonography and computed tomography alone using a threshold of 0.7 cm for malignant nodes.
However, the researchers detected a difference between methods using a threshold of 1 cm for malignant nodes.
Differences in accuracy were not detected in defining M-stage separately.
The team found no differences when comparing the accuracies of combined colonography with computed tomography followed by positron emission tomography.
The team noted that combined colonography affected consecutive therapy decisions in 9% of patients compared with conventional staging.
Dr Veit-Haibach's team concludes, “In this preliminary study, combined colonography is at least equivalent to computed tomography followed by positron emission tomography for tumor staging in patients with colorectal cancer.”
“Thus, combined colonography in conjunction with optical colonoscopy may be a suitable concept of tumor staging for patients with colorectal cancer.”