EAST MELBOURNE, Australia—A new prospective study has confirmed the usefulness of 18F-FDG PET in treatment planning for patients with confirmed or suspected colorectal cancer recurrence. In this study, 60% of planned surgeries were found to be unnecessary as the result of PET.
The study, led by Victor Kalff, MB, BS, and his colleagues in the Department of Diagnostic Imaging, Peter MacCallum Cancer Institute, East Melbourne, involved 102 patients referred for PET scan to evaluate suspected or confirmed regional recurrences of colorectal cancer. For 96 of these patients, their physicians had indicated a proposed treatment plan based on their current (pre-PET) status, and for 6 patients, their physicians preferred to wait for the PET results before creating a treatment plan. All were potential candidates for aggressive therapy if localized disease was confirmed.
The study was designed "to replicate as closely as possible the likely niche of PET in a clinical setting as an investigation performed after structural imaging," the authors said. Thus, patients with CT-confirmed disseminated metastases were excluded because PET was unlikely to alter their management even if additional disease sites were detected.
Patients were subdivided into five diagnostic subgroups: limited (solitary or adjacent) metastases amenable to aggressive local therapy; rising CEA levels with either normal or equivocal CT findings; increasing local symptoms; known recurrences but extent characterization needed for treatment planning; and new mass or residual mass suggestive of recurrence but unconfirmed by biopsy.
The following definitions were used for patient management: Active treatment (any combination of surgery, radiotherapy, or chemotherapy given for proven recurrence); supportive treatment (recurrence was proven but no active treatment was given); and observation (no recurrence found and routine surveillance planned).
Study Results
PET was shown to influence the management of 60 of the 102 patients (59%). In all 6 of the patients without a treatment plan, PET correctly guided management. Of the remaining 96 patients, the information provided by PET directly changed the planned management of 54 patients (56%) (J Nucl Med 43:492-499, 2002).
