Hybride imaging in advanced melanoma

Aim: To evaluate the usefulness of 18F-fluorodeoxyglucose positron emission tomography with computed tomography (18F-FDG PET/CT) in patients with advanced melanoma. Method: This study included 264 consecutive patients with melanoma who were sent for the 18F-FDG PET/CT. The inclusion criteria were as follows: histopathologically verified melanoma stage III or IV, the absence of other malignancy/infection; glycemia ≤ 11 mmol/l. The final study population consisted of 220 patients. After the first 18F-FDG PET/CT, the follow-up examination was performed after 11.81±7.99 months, for therapy response evaluation. Results: Pathological 18F-FDG PET/CT was present in 154 patients. Sensitivity of 18F-FDG PET/CT was estimated as 99%, specificity as 47%. There was no statistically significant difference between 18F-FDG PET/CT findings and gender (p> 0.05), and MDCT examination (p = 0.678). However, 18F-FDG PET/CT upstaged 45% patients, especially these with widespread disease. SUV max and inguinal disease localization (in patients who had lower extremities as primary localization of disease) were associated with progression free survival (PFS) (p < 0.05). SUV max (HR 1.03, CI 1.00-1.12, p=0.05) and locally advanced disease (HR 12.02, CI 1.13-148.00, p=0.04) were independent predictors of PFS. A follow up 18F-FDG PET/CT revealed active disease in 22/26 patients. Therapy type (immunotherapy or target therapy) did not correlate significantly with the 18F-FDG PET/CT follow up result (p=0.760, r=-0.354). Conclusion: 18F-FDG PET/CT has good sensitivity in the evaluation of advanced melanoma. Small lesions and brain localization reduce specificity of the examination, then MDCT, Mr are advised. Predictive factors SUV max and locally advanced disease, are more important than the timing of follow-up 18F-FDG PET/CT, since they were predictors of PFS. Follow up 18F-FDG PET/CT should be done at least in 6 months, only if there is suspicion of the presence of active disease.