TORONTO--Swiss researchers have shown that positron emission
tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) detects
metastases more accurately than conventional imaging techniques in
patients with malignant melanoma and increases the cost of staging by
"We found that whole body FDG-PET is a very effective
method for the staging of patients with high-risk malignant
melanoma," Hans C. Steinert, MD, Division of Nuclear Medicine,
University Hospital of Zurich, said at the Society of Nuclear
Medicine annual meeting.
The investigators reviewed the treatment records of 100 unselected
patients with either known metastatic melanoma or newly diagnosed
malignant melanoma and a tumor thickness greater than 1.5 mm (Breslow
scale). In patients with known metastatic disease, all metastases had
Two staging procedures were defined: Conventional staging consisted
of physical exam, chest x-ray, and ultrasound of lymph nodes and
abdomen. Any suspicious lesion after conventional staging resulted in
additional CT scans and histopathologic correlation. Examination via
whole body FDG-PET included inspection of the skin. Suspicious
lesions were confirmed by biopsy or another imaging modality.
PET Costs Only 1.7% More
The review found 172 staging protocols that could be analyzed for
cost comparison. The total cost of conventional staging was 257,224
Swiss francs ($172,691 United States), compared with 261,650 Swiss
francs ($175,663) for PET, which was only 1.7% more, he said.
Among the 72 patients with confirmed metastases, conventional staging
costs 227,445 Swiss francs ($152,699) while PET staging costs 201,414
Swiss francs ($135,223). In this subset, the PET protocol cost 11.4%
less than conventional staging. In addition, conventional staging
missed 15 (11%) of the 133 metastases because they were located out
of view of the various imaging methods. With PET, only 7 metastases
(5%) were missed.
"We feel that this study shows the cost effectiveness of
PET in staging patients with high-risk melanoma," Dr. Steinert
said. "We note that patients with a tumor thickness greater than
1.5 mm (Breslow scale) will benefit the most from whole body PET,
since this population has a greater risk of metastases. This may
represent a cost-effective cut-off for deciding whether to use PET."
A UCLA study showed that in the United States, conventional staging
costs more than reported by the Swiss group, but the US group
included additional tests in their conventional staging protocol.
The study included 60 patients with suspected melanoma recurrence and
looked at survival, using measures of life-expectancy based on the
literature, as well as cost effectiveness. Unlike the Swiss study,
body CT and brain MRI were included as part of conventional staging
for all patients. The UCLA study also took into account the savings
due to changes in patient management resulting from use of PET.
"Introducing PET into patient management had a substantial
effect on patient survival due to the proper shift of patients from
surgery to chemotherapy and vice versa," said Sanjiv Sam
Gambhir, MD, PhD, assistant professor of molecular and medical
pharmacology and clinical attending in nuclear medicine, UCLA.
The incremental cost-effectiveness ratio of PET vs conventional
staging, was $3,000 to $8,000 per year of life saved, far below the
standard $50,000/year of life saved used by US health economists to
characterize a cost-effective intervention. "This study supports
the use of whole body FDG-PET for the assessment of recurrent
melanoma patients," he said.