Comparison of [¹⁸F]FDG PET/CT and CT in the response assessment and clinical outcome prediction for immunotherapy in patients with advanced melanoma: a systematic review and meta-analysis.

Abstract

This study aimed to systematically compare the efficacy of [¹⁸F]FDG PET/CT and CT in evaluating the response to immunotherapy in patients with advanced melanoma. A comprehensive literature search was conducted across PubMed, Embase, Cochrane Library, Web of Science, and ClinicalTrials.gov. The study focused on comparing time-to-event hazard ratios (HRs) between patients categorized as complete response (CR) and non-complete response (non-CR) based on the two imaging assessment modalities. Eligible studies were selected based on the availability of both survival data and appropriate imaging methods, with special attention to the use of CT as part of PET/CT protocols in some cases. Additionally, PET and CT assessments were paired for each individual to analyze the efficacy of these imaging methods in detecting CR, assess the mismatch rate, and identify its causes. A review of 1445 candidate articles identified 15 eligible studies involving 952 patients. For CR and non-CR patients, the combined HR for PET was 4.10 (95% CI = 2.71-6.19), while for CT it was 1.25 (95% CI = 0.63-2.46). The high rate of PET-/CT+ discordance (48%, 95% CI: 42-53%) indicates that CT frequently misclassifies residual inflammation or fibrosis as active disease, whereas the absence of PET+/CT- cases (0%, 95% CI: 0-3%) highlights the high specificity of PET in detecting true residual tumors. This evidence supports prioritizing [¹⁸F]FDG PET/CT over CT for post-immunotherapy assessment of advanced melanoma. In direct comparison with CT, [¹⁸F]FDG PET/CT demonstrated superior predictive capabilities for immunotherapy response and survival outcomes. Question How do [¹⁸F]-FDG PET/CT and CT compare for assessing immunotherapy response and survival prediction in patients with advanced melanoma. Findings Meta-analysis of 15 studies showed [¹⁸F]-FDG PET/CT (HR = 4.10) had better predictive value than CT (HR = 1.25). Clinical relevance These findings support the prioritization of [¹⁸F]-FDG PET/CT over CT for post-immunotherapy assessment in advanced melanoma, as it provides more reliable predictions of treatment response and survival outcomes, helping clinicians make more informed therapeutic decisions.