EAST MELBOURNE, AustraliaA 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
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