To investigate the prognostic value of metabolic parameters measured by ¹⁸F-FDG PET/CT in patients with primary advanced cutaneous malignant melanoma (CMM).

A retrospective analysis was comprised of 42 patients with advanced CMM (15 males and 27 females; median age: 60.0 years) from Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School between June 2014 and December 2019. All patients were initially diagnosed by pathology, and underwent ¹⁸F-FDG PET/CT imaging. ¹⁸F-FDG PET/CT parameters including SUV_max, SUV_mean, total metabolic tumor volume (TMTV) and total lesion glycolysis (TLG) of metastatic lesions were measured. ROC curve analysis was performed to obtain the optimal cut-off values of those metabolic parameters for predicting progression-free survival (PFS) and over-all survival (OS). Patients were divided into different groups based on their metabolic parameters (≥cut-off values or <cut-off values), and Kaplan-Meier survival curve and log-rank test were used to analyze the OS/PFS differences between 2 groups. The independent prognostic risk factors of PFS and OS were screened by univariate analysis and Cox proportional risk model.

The median follow-up time of 42 patients with advanced CMM was 26.3 months, with 32 patients suffered from disease progression and 21 patients died, and the median survival was 33.1 months. The optimal cut-off values for PFS/OS were 4.63/4.77 for SUV_max, 3.31/3.31 for SUV_mean, 8.22 cm³/22.32 cm³ for TMTV, and 18.22 g/51.37 g for TLG, respectively. Kaplan-Meier analysis and log-rank test showed that patients with SUV_max ≥4.63 or SUV_mean ≥3.31 suffered from poorer PFS (χ² values: 7.12, 5.42, P values: 0.008, 0.020), meanwhile, patients with SUV_max ≥4.77 or TMTV≥22.32 cm³ or TLG≥51.37 g suffered from poorer OS (χ² value: 4.73, 5.60, 6.31, P values: 0.030, 0.018, 0.012). Multivariate analysis demonstrated that SUV_max was significant predictor for both PFS (hazard risk (HR)=3.03(95% CI: 1.23-7.45), P=0.016) and OS (HR=3.62(95% CI: 1.19-11.00), P=0.023), while TMTV and TLG were significant predictors for OS (HR: 2.87(95% CI: 1.20-6.87), 3.34(95% CI: 1.39-8.05); P values: 0.018, 0.007).

Baseline ¹⁸F-FDG PET/CT metabolic parameters have certain value in prediction of prognosis in patients with advanced CMM. SUV_max of metastatic lesions is an independent prognostic risk factor for both PFS and OS, and TMTV and TLG are independent prognostic risk factors for OS in patients with advanced CMM.

Melanoma; Skin; Positron-emission tomography; Tomography, X-ray computed; Fluorodeoxyglucose F18; Prognosis