JNM: FDG-PET better than CT for staging colorectal liver metastases

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FDG-PET, when combined with CT, is far more effective in its capability to diagnose and stage colorectal liver metastases than CT alone, according to a randomized controlled trial published in this month's Journal of Nuclear Medicine.

Theo J.M. Ruers, MD, from the department of surgery at Radboud University Nijmegen Medical Centre in Nijmegen, Netherlands, and colleagues noted that until now, definitive evidence that the addition of 18F-FDG PET to conventional staging leads to superior clinical results and improved clinical management in these patients has been lacking. They investigated whether the addition of 18F-FDG PET is beneficial and reduces the number of futile laparotomies.

In the randomized multi-center study of 150 patients with colorectal liver metastases recommended for surgery, the researchers randomly assigned participants to CT only (75) or CT plus 18F-FDG PET (75). They followed up with patients for at least three years. The primary outcome measure was futile laparotomy, defined as any laparotomy that did not result in complete tumor treatment, which revealed benign disease or that did not result in a disease-free survival period longer than six months. Also, the authors noted patient and tumor characteristics were similar for both groups

The investigators found that the number of futile laparotomies was 45 percent in the control arm without 18F-FDG PET and 28 percent in the experimental arm with 18F-FDG PET. The relative risk reduction was 38 percent.

Ruers and his colleagues concluded the number of futile laparotomies was reduced from 45 to 28 percent; thus, the addition of 18F-FDG PET to the work-up for surgical resection of colorectal liver metastases prevents unnecessary surgery in one of six patients.

However, the authors wrote that because data was collected between 2002 and 2006, they were forced to use separate PET and CT equipment in making their determinations.  With their recent capability to utilize PET/CT fusion technology, they noted that in the future "the actual reduction of futile laparotomies will be larger than 38 percent." 

The authors observed that the results observed in their study could differ from the addition of 18F-FDG PET to conventional staging in an actual clinical setting, because "all CT scans were more extensively reviewed by an expert panel than is standard routine before the patient was assessed for randomization. This means that in daily practice the value of additional 18F-FDG PET may even be higher than that observed in the present study."