Diagnostic and clinical value of [18F]FDG PET/CT in the follow-up regimen in IIA-IIID stage cutaneous malignant melanoma after first regional recurrence.

Background: Malignant melanoma stands out as a disease with highly aggressive behavior and frequent recurrences. It is crucial to find a non-invasive method for early recurrence detection which allows early and radical treatment. Our aim was to assess the diagnostic and clinical value of [18F]FDG PET/CT in the follow-up regimen of patients after radically treated first regional recurrence and for early detection of operable disease progression.

Material and methods: We performed [18F]FDG PET/CT in 96 consecutive patients who had a histologically proven regional recurrent disease that was radically treated. In 46 patients [18F]FDG PET/CT was used in the follow-up regimen and in the other 50 it was used for clarification of suspicious lesions seen in conventional studies. We explored the diagnostic performance of [18F]FDG PET/CT. We also compared the results with conventional studies and explored the clinical impact of [18F]FDG PET/CT by its ability to find localized disease progression in those groups.

Results: [18F]FDG PET/CT had better sensitivity, specificity, PPV and NPV, and accuracy in patients with symptoms. Good results in the second group had a high price for the patients, as there was a prevalence of distant metastatic disease in the second group - 64.0% vs. 28.3% in the surveillance group (p = 0.001). [18F]FDG PET/CT revealed more of the distant and in-transit lesions and assisted in lymph node detection by guiding the ultrasonography. Owing to the [18F]FDG PET/CT surveillance, 64.5% of all operable lesions were found in the surveillance group vs. only 35.5% in the second group, where the distant metastatic disease was prevalent.

Conclusions: [18F]FDG PET/CT used as a follow-up tool in the surveillance regimen of patients after the first recurrence showed excellent performance in timely and accurate recognition of operable lesions. It had significantly better performance than conventional studies in the follow-up regimen of the patients in this high risk of progression group.