Purpose of the Report
This study was performed to evaluate the prognostic relevance of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) measured using 18F FDG PET/CT in patients with primary cutaneous malignant melanoma (CMM).
Materials and Methods
We conducted a retrospective review (July 2005 to November 2010) of 41 patients with a histological diagnosis of CMM who underwent pretreatment 18F FDG PET/CT. PET parameters (maximum standardized uptake value [SUVmax], MTV, and TLG) of the primary tumor were measured. Clinical variables such as age, sex, clinical stage, location and thickness of the primary lesion, and existence of ulceration were also assessed. Univariate and multivariate analyses for disease-free survival (DFS) and melanoma-specific survival (MSS) were performed using the Kaplan-Meier method and Cox proportional hazards models.
Results
SUVmax and TLG were found to be significantly higher in patients with recurrence than in patients without recurrence (3.98 ± 2.91 vs 1.89 ± 1.35, P = 0.0145; 9.16 ± 8.44 vs 3.72 ± 3.64, P = 0.0249). SUVmax and TLG were also found to be significantly higher in nonsurvivors than in survivors (4.21 ± 3.06 vs 2.00 ± 1.46, P = 0.0260; 10.53 ± 8.83 vs 3.67 ± 3.44, P = 0.0170). The optimal cutoff values for DFS determined using a time-dependent receiver operating characteristic (ROC) curve were 1.8 for SUVmax, 6.07 cm3 for MTV, and 4.046 for TLG. Sixteen (39%) of the 41 patients experienced recurrence during the follow-up period. In univariate analysis, age (P = 0.0382), male sex (P = 0.0187), ulceration of the primary lesion (P = 0.0001), stage ≥ III (P = 0.0011), SUVmax greater than 1.8 (P = 0.0006), MTV greater than 6.07 cm3 (P = 0.0136), and TLG greater than 4.046 (P = 0.0010) affected DFS, whereas the other variables (location of the primary lesion and thickness of primary lesion) did not. After adjustment for the effects of the clinical parameters (age, sex, clinical stage, and existence of ulceration), SUVmax, MTV, and TLG were all significant predictors of DFS, and the best predictive factor was SUVmax. Thirteen (32%) of the 41 patients died because of CMM during the follow-up period. The optimal cutoff values for MSS determined using a time-dependent ROC curve were 2.2 for SUVmax, 4.02 cm3 for MTV, and 4.352 for TLG. In univariate analysis, ulceration of the primary lesion (P = 0.0005), SUVmax greater than 2.2 (P = 0.0001), MTV greater than 4.02 cm3 (P = 0.0071), and TLG greater than 4.352 (P = 0.0001) affected MSS, whereas the other variables (age, sex, clinical stage, primary lesion site, and thickness of the primary lesion) did not. After adjustment for the effect of the clinical parameter (existence of ulceration), MTV and TLG were significant predictors of MSS, and the best predictive factor of MSS was TLG.
Conclusions
Pretreatment MTV and TLG may be useful in stratifying the likelihood of recurrence and melanoma-specific death, and TLG was found to be the best predictive marker for predicting melanoma-specific death.
