PET AND CT USEFUL FOR N+ MELANOMA PATIENTS

NEW YORK (Reuters Health) Oct 12 - In staging melanoma patients with palpable lymph nodes, 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) are equivalent, but FDG-PET detects more metastatic sites, particularly bone and subcutaneous metastases, Dutch researchers report in the October 1st issue the Journal of Clinical Oncology.

Dr. Harald J. Hoekstra of University Medical Centre Groningen and colleagues came to these conclusions after prospectively studying data on 251 patients who underwent both FDG-PET and CT at five centers.

Distant metastases were suggested by FDG-PET in 32% of the patients and by CT in 29%. After correlation with cytology and histology or 6 months of follow-up, results proved correct in 27% of FDG-PET scans and 24% of CT scans.

The article notes that results were correct in 68 of 79 patients (86%) with positive FDG-PET scans and in 61 of 72 (85%) with positive CT scans.

False positive rates were not statistically different between hospitals, according to the researchers.

Significantly more sites were detected with FDG-PET than with CT (133 versus 112). This was particularly the case for bone metastases (27 versus 10) and subcutaneous metastases (11 versus 5).

Treatment changed in 19% of the patients. In most of these cases (79%), therapy was changed on the basis of both scans. Changes were made solely a result of FDG-PET in 17%, and solely a result of CT in 4%.

The researchers also calculated that FDG-PET provided value in addition to that of spiral CT in 17% of patients. Conversely, CT was of additional value in 9% of the patients.

"Due to the improved staging of melanoma patients with lymph node metastases," Dr. Hoekstra told Reuters Health, "surgical oncologists can better select melanoma patients for curative therapeutic lymph node dissection and refer patients with distant disease to a medical oncologist for systemic treatment."

Overall, he concluded, based on FDG-PET, "melanoma patients with lymph node metastases get the best tailored treatment."

J Clin Oncol 2009;27:4774-4780.