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 only 1.7%.
"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 been removed.
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.
