Prognostic value of pretreatment 18F-FDG PET/CT in patients with metastatic melanoma treated with anti-PD1 immunotherapy / 中华核医学与分子影像杂志

ABSTRACT

Objective:To assess the prognostic value of pretreatment 18F-FDG PET/CT metabolic parameters in patients with metastatic malignant melanoma treated with anti-programmed cell death-1 (PD1) immunotherapy. Methods:A retrospective analysis of 29 patients (15 males, 14 females, age (59.1±13.0) years) with pathologically diagnosed metastatic malignant melanoma in Nanjing Drum Tower Hospital between June 2017 and October 2020 was conducted. Anti-PD1 immunotherapy were performed in all patients after 18F-FDG PET/CT imaging. 18F-FDG PET/CT parameters including SUV max, bone marrow-to-liver SUV max ratio (BLR), spleen-to-liver SUV max ratio (SLR) were obtained. Total metabolic tumor volume (TMTV) and total lesion glycolysis (TLG) of primary lesions were measured automatically using the thresholds of 40%SUV max. The median value of each PET parameter was regarded as the threshold value and was used to divide patients into 2 groups (≥ and < the median value, respectively). Kaplan-Meier survival curve and Cox proportional risk model were used to analyze the overall survival (OS) differences between groups. Results:The median follow-up time was 15.0 months and 13 patients died. The median OS was 26.0(95% CI 20.4-31.6) months. The median SUV max, TMTV, TLG, BLR and SLR were 6.2, 8.2 cm 3, 38.6 g, 0.82 and 0.84 respectively. Kaplan-Meier method and log-rank test showed that differences of OS between SUV max≥6.2 and <6.2 groups, TLG≥38.6 g and <38.6 g groups, BLR≥0.82 and <0.82 groups, SLR≥0.84 and <0.84 groups were not significant ( χ2 values 0.01-0.35, P values 0.061-0.929), while patients with TMTV≥8.2 cm 3 suffered from poorer OS compared with those with TMTV<8.2 cm 3 ( χ2=5.90, P=0.015). Cox multivariate analysis showed that TMTV (hazard risk ( HR)=6.347, 95% CI 1.039-38.789) was a significant predictor of OS ( P=0.045). Conclusion:18F-FDG PET/CT parameter TMTV is the independent predictive factor of OS in metastatic melanoma treated with anti-PD1 immunotherapy.